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Fernandes PC, da Silva MD, Waddington-Cruz M, Gomes CP. Renal tubular acidosis in hereditary transthyretin amyloidosis (ATTRv). J Bras Nefrol 2024; 46:e20240016. [PMID: 39101566 PMCID: PMC11305565 DOI: 10.1590/2175-8239-jbn-2024-0016en] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 05/17/2024] [Indexed: 08/06/2024] Open
Abstract
INTRODUCTION Hereditary transthyretin amyloidosis (ATTRv) is a severe autosomal dominant systemic disease. It affects the peripheral and autonomic nervous systems, heart, kidneys, and eyes. Amyloid deposition has been demonstrated in the glomerular and tubulointerstitial compartments of the kidney. Therefore, urinary acidification disorders such as renal tubular acidosis (RTA) may be early manifestations of renal involvement in this population. OBJECTIVE To evaluate the prevalence of RTA in individuals with ATTRv. METHODS We included symptomatic and asymptomatic individuals with TTR mutation, older than 18 years, GFR >45 mL/min/1.73m2, without systemic metabolic acidosis. Urinary acidification protocol was performed with furosemide and fludrocortisone after 12 h of water deprivation (water deprivation test - WDT) and measurements of urine ammonium ( UNH 4 + ) and titratable acidity (UTA). Proximal RTA (pRTA) was diagnosed when FEHCO3>10%. Incomplete form distal RTA (dRTA) was diagnosed if UpH>5.3. RESULTS We selected 49 individuals with a mean age of 40 (35.5-56.5) years, 63% of which were female, 84% were Caucasian, and mean GFR was 85.5 ± 20.5 mL/min/1.73m2. 94% had the genetic variant Val50Met and 57% were symptomatic. The prevalence of pRTA was 2% and of dRTA was 16.3%. In the subgroup with dRTA, there was no significant increase in excretion of UNH 4 + and UTA. We observed a good correlation between UpH by potentiometry and UpH dipstick. A UpH<5.5 on the dipstick had 100% sensitivity and negative predictive value to exclude dRTA. CONCLUSION A high prevalence of RTA was found in individuals with TTR mutations. The UpH dipstick after WDT had good accuracy for screening for dRTA. Further studies are needed to evaluate the impact of early diagnosis and treatment of RTA in this population.
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Affiliation(s)
- Priscilla Cardim Fernandes
- Universidade Federal do Rio de Janeiro, Hospital Universitário Clementino Fraga Filho, Centro de Estudos em Paramiloidose Antônio Rodrigues de Mello, Rio de Janeiro, RJ, Brazil
| | - Moises Dias da Silva
- Universidade Federal do Rio de Janeiro, Hospital Universitário Clementino Fraga Filho, Centro de Estudos em Paramiloidose Antônio Rodrigues de Mello, Rio de Janeiro, RJ, Brazil
- Universidade Federal do Rio de Janeiro, Hospital Universitário Clementino Fraga Filho, Divisão de Nefrologia, Rio de Janeiro, RJ, Brazil
| | - Marcia Waddington-Cruz
- Universidade Federal do Rio de Janeiro, Hospital Universitário Clementino Fraga Filho, Centro de Estudos em Paramiloidose Antônio Rodrigues de Mello, Rio de Janeiro, RJ, Brazil
| | - Carlos Perez Gomes
- Universidade Federal do Rio de Janeiro, Hospital Universitário Clementino Fraga Filho, Centro de Estudos em Paramiloidose Antônio Rodrigues de Mello, Rio de Janeiro, RJ, Brazil
- Universidade Federal do Rio de Janeiro, Hospital Universitário Clementino Fraga Filho, Divisão de Nefrologia, Rio de Janeiro, RJ, Brazil
- Universidade Federal do Estado do Rio de Janeiro, Escola de Medicina e Cirurgia, Rio de Janeiro, RJ, Brazil
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Guimerà J, Martínez A, Quetglas JLB, Sanchis P, Costa-Bauzá A, Pieras E, Grases F. Phytate Effects on Incomplete Distal Renal Tubular Acidosis. J Clin Med 2024; 13:5059. [PMID: 39274272 PMCID: PMC11395708 DOI: 10.3390/jcm13175059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2024] [Revised: 08/22/2024] [Accepted: 08/23/2024] [Indexed: 09/16/2024] Open
Abstract
Background: Adults who have incomplete distal renal tubular acidosis (dRTA) may present with recurrent urolithiasis due to metabolic acidosis, leading to bone resorption, which in turn causes hypercalciuria and urine alkalinization (pH > 6.0). Oral potassium citrate is the most commonly used treatment for dRTA, but some patients cannot tolerate this treatment. The objective of this single-arm study was to evaluate the effect of phytate, an inhibitor of bone resorption, on calciuria of patients with incomplete dRTA. Methods: The calciuria levels of 16 patients who had incomplete dRTA with urolithiasis and could not tolerate potassium citrate treatment were recorded before (baseline) and after 6 months of treatment with oral calcium magnesium phytate (380 mg every 12 h). There were no dietary modifications or other treatments. Results: The baseline calciuria was 317 ± 81 mg/24 h and the level after 6 months was 221 ± 38 mg/24 h (p < 0.005). Conclusions: Our results suggest that calcium magnesium phytate should be considered as an alternative or adjunctive treatment for hypercalciuria in patients with incomplete dRTA.
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Affiliation(s)
- Jordi Guimerà
- Urology Department, Health Research Institute of the Balearic Islands (IdISBa), Son Espases University Hospital, 07120 Palma de Mallorca, Spain
| | - Ana Martínez
- Urology Department, Health Research Institute of the Balearic Islands (IdISBa), Son Espases University Hospital, 07120 Palma de Mallorca, Spain
| | - José Luis Bauzá Quetglas
- Urology Department, Health Research Institute of the Balearic Islands (IdISBa), Son Espases University Hospital, 07120 Palma de Mallorca, Spain
| | - Pilar Sanchis
- Laboratory of Renal Lithiasis Research, University Institute of Health Sciences Research (IUNICS), University of Balearic Islands, 07122 Palma de Mallorca, Spain
| | - Antonia Costa-Bauzá
- Laboratory of Renal Lithiasis Research, University Institute of Health Sciences Research (IUNICS), University of Balearic Islands, 07122 Palma de Mallorca, Spain
| | - Enrique Pieras
- Urology Department, Health Research Institute of the Balearic Islands (IdISBa), Son Espases University Hospital, 07120 Palma de Mallorca, Spain
| | - Felix Grases
- Laboratory of Renal Lithiasis Research, University Institute of Health Sciences Research (IUNICS), University of Balearic Islands, 07122 Palma de Mallorca, Spain
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Medina E, Ariceta G, Batlle D. Primary Distal Renal Tubular Acidosis: Toward an Optimal Correction of Metabolic Acidosis. Clin J Am Soc Nephrol 2024; 19:01277230-990000000-00420. [PMID: 38967973 PMCID: PMC11390030 DOI: 10.2215/cjn.0000000000000535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 06/28/2024] [Indexed: 07/07/2024]
Abstract
The term classic, type 1 renal tubular acidosis or primary distal renal tubular acidosis is used to designate patients with impaired ability to excrete acid normally in the urine as a result of tubular transport defects involving type A intercalated cells in the collecting duct. The clinical phenotype is largely characterized by the complications of chronic metabolic acidosis (MA): stunted growth, bone abnormalities, and nephrocalcinosis and nephrolithiasis that develop as the consequence of hypercalciuria and hypocitraturia. All these manifestations are preventable with early and sustained correction of MA with alkali therapy. The optimal target for plasma bicarbonate should be as close as possible to the range considered normal by current standards (between 23 and 28 mEq/L.). Most of the benefits of alkali therapy are tangible early in the course of the disease in childhood, but life-long treatment is required to prevent the vast array of complications attributable to chronic MA.
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Affiliation(s)
- Elba Medina
- Division of Nephrology, General Hospital of México, Eduardo Liceaga, México City, México and Master's and PhD Program in Dental and Health Medical Sciences, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gema Ariceta
- Pediatric Nephrology, University Hospital Vall d'Hebron, and Autonomous University of Barcelona, Barcelona, Spain
| | - Daniel Batlle
- Division of Nephrology/Hypertension, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
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Kunchur MG, Mauch TJ, Parkanzky M, Rahilly LJ. A review of renal tubular acidosis. J Vet Emerg Crit Care (San Antonio) 2024; 34:325-355. [PMID: 39023331 DOI: 10.1111/vec.13407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 10/14/2022] [Accepted: 11/11/2022] [Indexed: 07/20/2024]
Abstract
OBJECTIVE To review the current scientific literature on renal tubular acidosis (RTA) in people and small animals, focusing on diseases in veterinary medicine that result in secondary RTA. DATA SOURCES Scientific reviews and original research publications on people and small animals focusing on RTA. SUMMARY RTA is characterized by defective renal acid-base regulation that results in normal anion gap hyperchloremic metabolic acidosis. Renal acid-base regulation includes the reabsorption and regeneration of bicarbonate in the renal proximal tubule and collecting ducts and the process of ammoniagenesis. RTA occurs as a primary genetic disorder or secondary to disease conditions. Based on pathophysiology, RTA is classified as distal or type 1 RTA, proximal or type 2 RTA, type 3 RTA or carbonic anhydrase II mutation, and type 4 or hyperkalemic RTA. Fanconi syndrome comprises proximal RTA with additional defects in proximal tubular function. Extensive research elucidating the genetic basis of RTA in people exists. RTA is a genetic disorder in the Basenji breed of dogs, where the mutation is known. Secondary RTA in human and veterinary medicine is the sequela of diseases that include immune-mediated, toxic, and infectious causes. Diagnosis and characterization of RTA include the measurement of urine pH and the evaluation of renal handling of substances that should affect acid or bicarbonate excretion. CONCLUSIONS Commonality exists between human and veterinary medicine among the types of RTA. Many genetic defects causing primary RTA are identified in people, but those in companion animals other than in the Basenji are unknown. Critically ill veterinary patients are often admitted to the ICU for diseases associated with secondary RTA, or they may develop RTA while hospitalized. Recognition and treatment of RTA may reverse tubular dysfunction and promote recovery by correcting metabolic acidosis.
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Affiliation(s)
| | - Teri Jo Mauch
- University of Nebraska Medical Center and Children's Hospital, Omaha, Nebraska, USA
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | | | - Louisa J Rahilly
- Cape Cod Veterinary Specialists, Buzzards Bay, Massachusetts, USA
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Coradin R, Lopes MLL, Goldani JC, Ventura PE, Keitel E. Hypocitraturia as a biomarker of renal tubular acidosis in patients with Sjögren's disease. Adv Rheumatol 2024; 64:45. [PMID: 38831360 DOI: 10.1186/s42358-024-00387-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 05/27/2024] [Indexed: 06/05/2024] Open
Abstract
INTRODUCTION Sjögren's disease (SD) is an immune-mediated chronic inflammatory disease that affects epithelial tissues, mainly salivary and lacrimal glands. It also presents extraglandular manifestations. The main renal manifestation is tubulointerstitial nephritis (TIN), which can manifest as renal tubular acidosis (RTA). Urinary citrate may be a biomarker of RTA in these patients. The objective of this study was to evaluate whether hypocitraturia is a predictive biomarker of RTA in a sample of patients with SD in a tertiary hospital in southern Brazil. METHODS All patients with SD who met the inclusion criteria and who participated in the rheumatology outpatient clinic of the Irmandade Santa Casa de Misericórdia de Porto Alegre were included. Demographic, SD, serological and urinary data were obtained. RTA was considered in those patients who persistently presented urinary pH above 5.5 and serum pH below 7.35. Patients who persistently had urinary pH above 5.5 underwent a urinary acidification test with furosemide and fludrocortisone. These patients received 1 mg of fludrocortisone and 40 mg of furosemide and had their urine samples tested 2, 4 and 6 h after taking the medications. The test was stopped at any urine sample with pH 5.5 or less. The variables were expressed as mean and standard deviation or interquartile range. The association between hypocitraturia and RTA was assessed using the chi-square. RESULTS Forty-two patients were included, 95.2% female with a median age of 61.73 years. The prevalence of complete distal RTA was 4.88%. Twenty-eight patients underwent urine acidification testing. Five patients had hypocitraturia, and two of them had complete distal RTA. The association between hypocitraturia and RTA was statistically significant (p < 0.012), with a sensitivity of 100%, specificity of 91.2% and accuracy of 91.7%. The negative predictive value was 100%. The global renal assessment of the population demonstrated two patients with RTA, one patient with decreased renal function and six patients with proteinuria greater than 0.5 g/24 h. CONCLUSION The prevalence of RTA in the studied population was 4.88%. Hypocitraturia had high sensitivity and accuracy for the diagnosis of RTA.
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Affiliation(s)
- Rafael Coradin
- Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil.
| | | | | | | | - Elizete Keitel
- Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
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Price EJ, Benjamin S, Bombardieri M, Bowman S, Carty S, Ciurtin C, Crampton B, Dawson A, Fisher BA, Giles I, Glennon P, Gupta M, Hackett KL, Larkin G, Ng WF, Ramanan AV, Rassam S, Rauz S, Smith G, Sutcliffe N, Tappuni A, Walsh SB. British Society for Rheumatology guideline on management of adult and juvenile onset Sjögren disease. Rheumatology (Oxford) 2024:keae152. [PMID: 38621708 DOI: 10.1093/rheumatology/keae152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 03/02/2024] [Indexed: 04/17/2024] Open
Abstract
Sjögren disease (SD) is a chronic, autoimmune disease of unknown aetiology with significant impact on quality of life. Although dryness (sicca) of the eyes and mouth are the classically described features, dryness of other mucosal surfaces and systemic manifestations are common. The key management aim should be to empower the individual to manage their condition-conserving, replacing and stimulating secretions; and preventing damage and suppressing systemic disease activity. This guideline builds on and widens the recommendations developed for the first guideline published in 2017. We have included advice on the management of children and adolescents where appropriate to provide a comprehensive guideline for UK-based rheumatology teams.
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Affiliation(s)
- Elizabeth J Price
- Department of Rheumatology, Great Western Hospital NHS Foundation Trust, Swindon, UK
| | - Stuart Benjamin
- The Academy Library and Information Service, Great Western Hospital NHS Foundation Trust, Swindon, UK
| | - Michele Bombardieri
- Department of Rheumatology, Barts and The London School of Medicine and Dentistry, Barts Health NHS Trust, London, UK
- Centre for Experimental Medicine and Rheumatology, The William Harvey Research Institute, Queen Mary University of London, London, UK
| | - Simon Bowman
- Department of Rheumatology, Milton Keynes University Hospital, Milton Keynes, UK
- Department of Rheumatology, University Hospitals Birmingham NHSFT, Birmingham, UK
- Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
| | - Sara Carty
- Department of Rheumatology, Great Western Hospital NHS Foundation Trust, Swindon, UK
| | - Coziana Ciurtin
- Centre for Rheumatology, Division of Medicine, University College London, London, UK
| | - Bridget Crampton
- Patient Representative, Sjogren's UK Helpline Lead, Sjogren's UK (British Sjögren's Syndrome Association), Birmingham, UK
| | - Annabel Dawson
- Patient Representative, Sjogren's UK (British Sjögren's Syndrome Association), Birmingham, UK
| | - Benjamin A Fisher
- Rheumatology Research Group, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
- National Institute for Health Research (NIHR) Birmingham Biomedical Research Centre and Department of Rheumatology, University Hospitals Birmingham NHS Foundation Trust, Birmingham, UK
| | - Ian Giles
- Centre for Rheumatology, Division of Medicine, University College London, London, UK
| | - Peter Glennon
- General Practice, NHS Staffordshire & Stoke on Trent ICB, Stafford, UK
| | - Monica Gupta
- Department of Rheumatology, Gartnavel General Hospital, Glasgow, UK
| | - Katie L Hackett
- Department of Social Work, Education and Community Wellbeing, Northumbria University, Newcastle upon Tyne, UK
| | | | - Wan-Fai Ng
- Translational and Clinical Research Institute & Newcastle NIHR Biomedical Research Centre, Newcastle University, Newcastle upon Tyne, UK
- Department of Rheumatology, Newcastle upon Tyne NHS Foundation Trust, Newcastle upon Tyne, UK
| | - Athimalaipet V Ramanan
- Department of Paediatric Rheumatology, Bristol Royal Hospital for Children, Bristol, UK
- Translational Health Sciences, University of Bristol, Bristol, UK
| | - Saad Rassam
- Haematology and Haemato-Oncology, KIMS Hospital, Maidstone, Kent, UK
| | - Saaeha Rauz
- Ophthalmology, Institute of Inflammation and Ageing, University of Birmingham, Birmingham, UK
- Birmingham and Midland Eye Centre, Sandwell and West Birmingham NHS Trust, Birmingham, UK
| | - Guy Smith
- Department of Ophthalmology, Great Western Hospital NHS Foundation Trust, Swindon, UK
| | | | - Anwar Tappuni
- Institute of Dentistry, Queen Mary University of London, London, UK
| | - Stephen B Walsh
- London Tubular Centre, University College London, London, UK
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Capolongo G, Damiano S, Suzumoto Y, Zacchia M, Rizzo M, Zona E, Pollastro RM, Simeoni M, Ciarcia R, Trepiccione F, Capasso G. Cyclosporin-induced hypertension is associated with the up-regulation of Na+-K+-2Cl- cotransporter (NKCC2). Nephrol Dial Transplant 2024; 39:297-304. [PMID: 37463050 PMCID: PMC10828191 DOI: 10.1093/ndt/gfad161] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Indexed: 02/01/2024] Open
Abstract
BACKGROUND The use of cyclosporin A (CsA) is hampered by the development of nephrotoxicity including hypertension, which is partially dependent on renal sodium retention. To address this issue, we have investigated in vivo sodium reabsorption in different nephron segments of CsA-treated rats through micropuncture study coupled to expression analyses of sodium transporters. To translate the findings in rats to human, kidney-transplanted patients having CsA treatment were enrolled in the study. METHODS Adult male Sprague-Dawley rats were treated with CsA (15 mg/kg/day) for 21 days, followed by micropuncture study and expression analyses of sodium transporters. CsA-treated kidney-transplanted patients with resistant hypertension were challenged with 50 mg furosemide. RESULTS CsA-treated rats developed hypertension associated with reduced glomerular filtration rate. In vivo microperfusion study demonstrated a significant decrease in rate of absolute fluid reabsorption in the proximal tubule but enhanced sodium reabsorption in the thick ascending limb of Henle's loop (TAL). Expression analyses of sodium transporters at the same nephron segments further revealed a reduction in Na+-H+ exchanger isoform 3 (NHE3) in the renal cortex, while TAL-specific, furosemide-sensitive Na+-K+-2Cl- cotransporter (NKCC2) and NHE3 were significantly upregulated in the inner stripe of outer medulla. CsA-treated patients had a larger excretion of urinary NKCC2 protein at basal condition, and higher diuretic response to furosemide, showing increased FeNa+, FeCl- and FeCa2+ compared with both healthy controls and FK506-treated transplanted patients. CONCLUSION Altogether, these findings suggest that up-regulation of NKCC2 along the TAL facilitates sodium retention and contributes to the development of CsA-induced hypertension.
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Affiliation(s)
- Giovanna Capolongo
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Sara Damiano
- Department of Veterinary Medicine and Animal Productions, University of Naples, Naples, Italy
| | - Yoko Suzumoto
- Biogem, Institute of Molecular Biology and Genetics, Ariano Irpino, Italy
| | - Miriam Zacchia
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Maria Rizzo
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Enrica Zona
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Rosa Maria Pollastro
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Mariadelina Simeoni
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
| | - Roberto Ciarcia
- Department of Veterinary Medicine and Animal Productions, University of Naples, Naples, Italy
| | - Francesco Trepiccione
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
- Biogem, Institute of Molecular Biology and Genetics, Ariano Irpino, Italy
| | - Giovambattista Capasso
- Department of Translational Medical Sciences, University of Campania “Luigi Vanvitelli”, Naples, Italy
- Biogem, Institute of Molecular Biology and Genetics, Ariano Irpino, Italy
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Ayasse N, Berg P, Svendsen SL, Rousing AQ, Sørensen MV, Fedosova NU, Leipziger J. Trimethoprim inhibits renal H +-K +-ATPase in states of K + depletion. Am J Physiol Renal Physiol 2024; 326:F143-F151. [PMID: 37942538 DOI: 10.1152/ajprenal.00273.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/23/2023] [Accepted: 11/06/2023] [Indexed: 11/10/2023] Open
Abstract
There is growing consensus that under physiological conditions, collecting duct H+ secretion is independent of epithelial Na+ channel (ENaC) activity. We have recently shown that the direct ENaC inhibitor benzamil acutely impairs H+ excretion by blocking renal H+-K+-ATPase. However, the question remains whether inhibition of ENaC per se causes alterations in renal H+ excretion. To revisit this question, we studied the effect of the antibiotic trimethoprim (TMP), which is well known to cause K+ retention by direct ENaC inhibition. The acute effect of TMP (5 µg/g body wt) was assessed in bladder-catheterized mice, allowing real-time measurement of urinary pH, electrolyte, and acid excretion. Dietary K+ depletion was used to increase renal H+-K+-ATPase activity. In addition, the effect of TMP was investigated in vitro using pig gastric H+-K+-ATPase-enriched membrane vesicles. TMP acutely increased natriuresis and decreased kaliuresis, confirming its ENaC-inhibiting property. Under control diet conditions, TMP had no effect on urinary pH or acid excretion. Interestingly, K+ depletion unmasked an acute urine alkalizing effect of TMP. This finding was corroborated by in vitro experiments showing that TMP inhibits H+-K+-ATPase activity, albeit at much higher concentrations than benzamil. In conclusion, under control diet conditions, TMP inhibited ENaC function without changing urinary H+ excretion. This finding further supports the hypothesis that the inhibition of ENaC per se does not impair H+ excretion in the collecting duct. Moreover, TMP-induced urinary alkalization in animals fed a low-K+ diet highlights the importance of renal H+-K+-ATPase-mediated H+ secretion in states of K+ depletion.NEW & NOTEWORTHY The antibiotic trimethoprim (TMP) often mediates K+ retention and metabolic acidosis. We suggest a revision of the underlying mechanism that causes metabolic acidosis. Our results indicate that TMP-induced metabolic acidosis is secondary to epithelial Na+ channel-dependent K+ retention. Under control dietary conditions, TMP does not per se inhibit collecting duct H+ secretion. These findings add further argument against a physiologically relevant voltage-dependent mechanism of collecting duct H+ excretion.
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Affiliation(s)
- Niklas Ayasse
- Department of Biomedicine, Physiology, Aarhus University, Aarhus, Denmark
- Vth Department of Medicine, University Hospital Mannheim, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Peder Berg
- Department of Biomedicine, Physiology, Aarhus University, Aarhus, Denmark
| | - Samuel L Svendsen
- Department of Biomedicine, Physiology, Aarhus University, Aarhus, Denmark
| | | | | | - Natalya U Fedosova
- Department of Biomedicine, Physiology, Aarhus University, Aarhus, Denmark
| | - Jens Leipziger
- Department of Biomedicine, Physiology, Aarhus University, Aarhus, Denmark
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9
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Wagner CA, Unwin R, Lopez-Garcia SC, Kleta R, Bockenhauer D, Walsh S. The pathophysiology of distal renal tubular acidosis. Nat Rev Nephrol 2023; 19:384-400. [PMID: 37016093 DOI: 10.1038/s41581-023-00699-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2023] [Indexed: 04/06/2023]
Abstract
The kidneys have a central role in the control of acid-base homeostasis owing to bicarbonate reabsorption and production of ammonia and ammonium in the proximal tubule and active acid secretion along the collecting duct. Impaired acid excretion by the collecting duct system causes distal renal tubular acidosis (dRTA), which is characterized by the failure to acidify urine below pH 5.5. This defect originates from reduced function of acid-secretory type A intercalated cells. Inherited forms of dRTA are caused by variants in SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, WDR72 and probably in other genes that are yet to be discovered. Inheritance of dRTA follows autosomal-dominant and -recessive patterns. Acquired forms of dRTA are caused by various types of autoimmune diseases or adverse effects of some drugs. Incomplete dRTA is frequently found in patients with and without kidney stone disease. These patients fail to appropriately acidify their urine when challenged, suggesting that incomplete dRTA may represent an intermediate state in the spectrum of the ability to excrete acids. Unrecognized or insufficiently treated dRTA can cause rickets and failure to thrive in children, osteomalacia in adults, nephrolithiasis and nephrocalcinosis. Electrolyte disorders are also often present and poorly controlled dRTA can increase the risk of developing chronic kidney disease.
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Affiliation(s)
- Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland.
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK.
| | - Robert Unwin
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
| | - Sergio C Lopez-Garcia
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Robert Kleta
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
| | - Detlef Bockenhauer
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Stephen Walsh
- Department of Renal Medicine, Royal Free Hospital, University College London, London, UK
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10
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Uribarri J, Goldfarb DS, Raphael KL, Rein JL, Asplin JR. Beyond the Urine Anion Gap: In Support of the Direct Measurement of Urinary Ammonium. Am J Kidney Dis 2022; 80:667-676. [PMID: 35810828 DOI: 10.1053/j.ajkd.2022.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/10/2022] [Indexed: 02/02/2023]
Abstract
Ammonium is a major urinary buffer that is necessary for the normal excretion of the daily acid load. Its urinary rate of excretion (UNH4) may be increased several fold in the presence of extrarenal metabolic acidosis. Therefore, measurement of UNH4 can provide important clues about causes of metabolic acidosis. Because UNH4 is not commonly measured in clinical laboratories, the urinary anion gap (UAG) was proposed as its surrogate about 4 decades ago, and it is still frequently used for that purpose. Several published studies strongly suggest that UAG is not a good index of UNH4 and support the concept that direct measurement of UNH4 is an important parameter to define in clinical nephrology. Low UNH4 levels have recently been found to be associated with a higher risk of metabolic acidosis, loss of kidney function, and death in persons with chronic kidney disease, while surrogates like the UAG do not recapitulate this risk. In order to advance the field it is necessary for the medical community to become more familiar with UNH4 levels in a variety of clinical settings. Herein, we review the literature, searching for available data on UNH4 under normal and various pathological conditions, in an attempt to establish reference values to interpret UNH4 results if and when UNH4 measurements become available as a routine clinical test. In addition, we present original data in 2 large populations that provide further evidence that the UAG is not a good predictor of UNH4. Measurement of urine NH4 holds promise to aid clinicians in the care of patients, and we encourage further research to determine its best diagnostic usage.
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Affiliation(s)
- Jaime Uribarri
- Renal Division, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.
| | | | - Kalani L Raphael
- Oregon Health & Science University and VA Portland Health Care System, Portland, Oregon
| | - Joshua L Rein
- Renal Division, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - John R Asplin
- Litholink Corporation, Laboratory Corporation of America Holdings, Chicago, Illinois
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11
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Lionet A, Roger C, Biardeau X, Daudon M, Letavernier E. Chronic urine acidification by fludrocortisone to treat infectious kidney stones. CR CHIM 2022. [DOI: 10.5802/crchim.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Recommendations for evaluation and diagnosis of extra-glandular manifestations of primary sjogren syndrome: results of an epidemiologic systematic review/meta-analysis and a consensus guideline from the Brazilian Society of Rheumatology (articular, pulmonary and renal). Adv Rheumatol 2022; 62:18. [PMID: 35650656 DOI: 10.1186/s42358-022-00248-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Accepted: 05/15/2022] [Indexed: 11/10/2022] Open
Abstract
Sjogren's Syndrome (SS) is an autoimmune disease characterized by lymphocytic infiltration of the exocrine glands and other organs, associated with sicca syndrome but also with systemic involvement with varying degrees of severity. Despite their importance, these systemic manifestations are not routinely evaluated and there is no homogenous approach to their diagnosis or evaluation. To close this gap, a panel of experts from the Brazilian Society of Rheumatology conducted a systematic review and meta-analysis on the identification of epidemiologic and clinical features of these manifestations and made recommendations based on the findings. Agreement between the experts was achieved using the Delphi method. The first part of this guideline summarizes the most important topics, and 11 recommendations are provided for the articular, pulmonary, and renal care of SS patients.
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13
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Alhasan K, D'Alessandri-Silva C, Mongia A, Topaloglu R, Tasic V, Filler G. Young Adults With Hereditary Tubular Diseases: Practical Aspects for Adult-Focused Colleagues. Adv Chronic Kidney Dis 2022; 29:292-307. [PMID: 36084976 DOI: 10.1053/j.ackd.2021.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/07/2021] [Accepted: 11/15/2021] [Indexed: 11/11/2022]
Abstract
Recent advances in the management of kidney tubular diseases have resulted in a significant cohort of adolescents and young adults transitioning from pediatric- to adult-focused care. Most of the patients under adult-focused care have glomerular diseases, whereas rarer tubular diseases form a considerable proportion of pediatric patients. The purpose of this review is to highlight the clinical signs and symptoms of tubular disorders, as well as their diagnostic workup, including laboratory findings and imaging, during young adulthood. We will then discuss more common disorders such as cystinosis, cystinuria, distal kidney tubular acidosis, congenital nephrogenic diabetes insipidus, Dent disease, rickets, hypercalciuria, and syndromes such as Bartter, Fanconi, Gitelman, Liddle, and Lowe. This review is a practical guide on the diagnostic and therapeutic approach of tubular conditions affecting young adults who are transitioning to adult-focused care.
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Affiliation(s)
- Khalid Alhasan
- Department of Pediatrics, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Cynthia D'Alessandri-Silva
- Department of Pediatrics, University of Connecticut School of Medicine, Farmington, and Nephrology, Connecticut Children's Medical Center, Hartford, CT
| | - Anil Mongia
- Department of Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY
| | - Rezan Topaloglu
- Department of Paediatrics, Division of Pediatric Nephrology, Hacettepe University School of Medicine, Ankara, Turkey
| | - Velibor Tasic
- University Children's Hospital, Medical School, Skopje, North Macedonia
| | - Guido Filler
- Department of Paediatrics, Division of Pediatric Nephrology, Western University, London, ON, Canada; Department of Medicine, Western University, London, ON, Canada; Department of Pathology and Laboratory Medicine, Western University, London, ON, Canada.
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14
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Boro H, Khatiwada S, Alam S, Kubihal S, Dogra V, Mannar V, Khadgawat R. Renal Tubular Acidosis Manifesting as Severe Metabolic Bone Disease. TOUCHREVIEWS IN ENDOCRINOLOGY 2022; 17:59-67. [PMID: 35118447 DOI: 10.17925/ee.2021.17.1.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 02/05/2021] [Indexed: 11/24/2022]
Abstract
Renal tubular acidosis (RTA) is a condition characterized by normal anion gap metabolic acidosis. Type 1 and type 2 RTA are the most common, and are caused by defective secretion of hydrogen ions and impaired absorption of bicarbonate, respectively. Long-standing uncorrected acidosis can lead to metabolic bone disease (MBD). Rickets and osteomalacia remain the commonest manifestations of uncorrected RTA. In addition, there can be a myriad of other skeletal manifestations like fractures, pseudofractures, secondary osteoporosis and even sclerotic bone disease. The postulated mechanism for bone involvement includes acidosis-mediated exaggerated osteoclastic bone resorption. Other contributory factors include abnormal renal handling of phosphate leading to hypophosphataemia in proximal RTA, and impaired vitamin D metabolism and action. In distal RTA, hypercalciuria and secondary hyperparathyroidism may play a key role for bone involvement. Recognizing the disease in its early course is important to prevent permanent sequelae of skeletal involvement. Most of these patients may, in fact, undergo orthopaedic interventions without primary correction of acidosis. We describe five cases who presented with MBD in varied forms. While evaluating the aetiology of MBD, they were diagnosed with RTA. Subsequently, we attempted to analyse the causes of RTA. Although the common causes were ruled out, genetic aetiology could not be ascertained due to resource constraints. RTA remains an important differential diagnosis of MBD. More awareness is required to diagnose the disease early and to treat it adequately. Our case series is an attempt to provide the clinical, biochemical and skeletal spectrum of RTA. In addition, we have attempted to provide algorithms for the approach and evaluation of RTA along with their varied causes.
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Affiliation(s)
- Hiya Boro
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India
| | - Saurav Khatiwada
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India
| | - Sarah Alam
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India
| | - Suraj Kubihal
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India
| | - Vinay Dogra
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India
| | - Velmurugan Mannar
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India
| | - Rajesh Khadgawat
- Department of Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, India
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15
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Díaz-Anadón L, Cardo L, Santos F, Gil-Peña H. Evaluation of urinary acidification in children: Clinical utility. Front Pediatr 2022; 10:1051481. [PMID: 36389372 PMCID: PMC9660234 DOI: 10.3389/fped.2022.1051481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 10/10/2022] [Indexed: 11/13/2022] Open
Abstract
The kidney plays a fundamental role in acid-base homeostasis by reabsorbing the filtered bicarbonate and by generating new bicarbonate, to replace that consumed in the buffering of non-volatile acids, a process that leads to the acidification of urine and the excretion of ammonium (NH4 +). Therefore, urine pH (UpH) and urinary NH4 + (UNH4 +) are valuable parameters to assess urinary acidification. The adaptation of automated plasma NH4 + quantification methods to measure UNH4 + has proven to be an accurate and feasible technique, with diverse potential indications in clinical practice. Recently, reference values for spot urine NH4 +/creatinine ratio in children have been published. UpH and UNH4 +, aside from their classical application in the study of metabolic acidosis, have shown to be useful in the identification of incomplete distal renal tubular acidosis (dRTA), an acidification disorder, without overt metabolic acidosis, extensively described in adults, and barely known in children, in whom it has been found to be associated to hypocitraturia, congenital kidney abnormalities and growth impairment. In addition, a low UNH4 + in chronic kidney disease (CKD) is a risk factor for glomerular filtration decay and mortality in adults, even in the absence of overt metabolic acidosis. We here emphasize on the need of measuring UpH and UNH4 + in pediatric population, establishing reference values, as well as exploring their application in metabolic acidosis, CKD and disorders associated with incomplete dRTA, including growth retardation of unknown cause.
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Affiliation(s)
- Lucas Díaz-Anadón
- Division of Pediatric Nephrology, Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain.,Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain
| | - Leire Cardo
- Clinical Biochemistry Department, Laboratory of Medicine, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain
| | - Fernando Santos
- Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain
| | - Helena Gil-Peña
- Division of Pediatric Nephrology, Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain.,Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain.,Section of Pediatrics, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Asturias, Spain
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16
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Sromicki J, Kacl G, Föhl M, Hess B. Prospective long-term evaluation of incomplete distal renal tubular acidosis in idiopathic calcium nephrolithiasis diagnosed by low-dose NH 4CL loading - gender prevalences and impact of alkali treatment. J Nephrol 2022; 35:1619-1626. [PMID: 34973150 PMCID: PMC9300500 DOI: 10.1007/s40620-021-01207-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 11/09/2021] [Indexed: 11/23/2022]
Abstract
Purpose Prospective evaluation of the prevalence of incomplete distal renal tubular acidosis (idRTA) in idiopathic calcium stone formers (ICSF) diagnosed by half-dose ammonium chloride loading (NH4Cl, 0.05 g/kg body weight/day) and impact of alkali treatment of idRTA. Methods Evaluation of 386 consecutive idiopathic calcium stone formers (ICSF) (280 males, 106 females) for idRTA. If screening fasting urine pH was > 5.80, 1-day NH4Cl loading was performed without severe adverse effects. Normally, urine pH falls below 5.45. Results Sixty-four idiopathic calcium stone formers exhibited idRTA, one complete dRTA. Prevalence was higher in women (25.4%) than in men (13.6%). Thus, for more equilibrated comparisons, we formed pairs of 62 idiopathic calcium stone formers (ICSF) with and 62 without idRTA, matched for gender, age, BMI and serum creatinine. Idiopathic calcium stone formers with idRTA more often had hypercalciuria (p < 0.025) and urine citrate < 2 mmol/d (p < 0.05), formed calcium phosphate stones more frequently, exhibited higher numbers of stones/year (1.4 ± 1.5 vs. 0.9 ± 0.8, p = 0.034) and 2.5 times more intrarenal calcifications (4.6 ± 5.9 vs. 1.8 ± 3.6, p = 0.002). All idiopathic calcium stone formers with idRTA were recommended chronic alkali therapy. After 4–15 years of follow-up, stone events /years follow-up (stone passage or urologic intervention) were higher in patients non-adherent to alkali therapy (0.61 ± 0.92) than in patients adherent to treatment (0.11 ± 0.21, p = 0.006). Conclusion Incomplete distal renal tubular acidosis is 1.8-fold more prevalent among female idiopathic calcium stone formers, predicts more stone recurrences, predisposes to calcium phosphate stones and is associated with 2.5 times more intrarenal calcifications vs. non-idRTA patients. Chronic alkali treatment reduces clinical stone recurrences by 5.5 times. Graphical abstract ![]()
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Affiliation(s)
- Juri Sromicki
- Internal Medicine and Nephrology, Kidney Stone Center Zurich, Klinik Im Park and University of Zurich, Bellariastrasse 38, CH-8038, Zurich, Switzerland.,Department of Cardiac Surgery, University Hospital, Zurich, Switzerland
| | - Georg Kacl
- Internal Medicine and Nephrology, Kidney Stone Center Zurich, Klinik Im Park and University of Zurich, Bellariastrasse 38, CH-8038, Zurich, Switzerland.,Radiology, Klinik Im Park, Zurich, Switzerland
| | - Malin Föhl
- Internal Medicine and Nephrology, Kidney Stone Center Zurich, Klinik Im Park and University of Zurich, Bellariastrasse 38, CH-8038, Zurich, Switzerland
| | - Bernhard Hess
- Internal Medicine and Nephrology, Kidney Stone Center Zurich, Klinik Im Park and University of Zurich, Bellariastrasse 38, CH-8038, Zurich, Switzerland.
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17
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D'Ambrosio V, Azzarà A, Sangiorgi E, Gurrieri F, Hess B, Gambaro G, Ferraro PM. Results of a Gene Panel Approach in a Cohort of Patients with Incomplete Distal Renal Tubular Acidosis and Nephrolithiasis. Kidney Blood Press Res 2021; 46:469-474. [PMID: 34107482 DOI: 10.1159/000516389] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 04/07/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Distal renal tubular acidosis (dRTA) is characterized by an impairment of urinary acidification resulting in metabolic acidosis, hypokalemia, and inappropriately elevated urine pH. If not treated, this chronic condition eventually leads to nephrocalcinosis, nephrolithiasis, impaired renal function, and bone demineralization. dRTA is a well-defined entity that can be diagnosed by genetic testing of 5 genes known to be disease-causative. Incomplete dRTA (idRTA) is defined as impaired urinary acidification that does not lead to overt metabolic acidosis and therefore can be diagnosed if patients fail to adequately acidify urine after an ammonium chloride (NH4Cl) challenge or furosemide and fludrocortisone test. It is still uncertain whether idRTA represents a distinct entity or is part of the dRTA spectrum and whether it is caused by mutations in the same genes of overt dRTA. METHODS In this cross-sectional study, we investigated a group of 22 stone formers whose clinical features were suspicious of idRTA. They underwent an NH4Cl challenge and were found to have impaired urinary acidification ability. These patients were then analyzed by genetic testing with sequencing of 5 genes: SLC4A1, ATP6V1B1, ATP6V0A4, FOXI1, and WDR72. RESULTS Two unrelated individuals were found to have two different variants in SLC4A1 that had never been described before. CONCLUSIONS Our results suggest the involvement of other genes or nongenetic tubular dysfunction in the pathogenesis of idRTA in stone formers. However, genetic testing may represent a cost-effective tool to recognize, treat, and prevent complications in these patients.
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Affiliation(s)
- Viola D'Ambrosio
- U.O.S. Terapia Conservativa della Malattia Renale Cronica, U.O.C. Nefrologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.,Università Cattolica del Sacro Cuore, Rome, Italy
| | - Alessia Azzarà
- Istituto di Medicina Genomica, Fondazione Policlinico Universitario A. Gemelli IRCCS - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Eugenio Sangiorgi
- Università Cattolica del Sacro Cuore, Rome, Italy.,Istituto di Medicina Genomica, Fondazione Policlinico Universitario A. Gemelli IRCCS - Università Cattolica del Sacro Cuore, Rome, Italy
| | - Fiorella Gurrieri
- Unità di genetica Medica e Funzionale, Università Campus Bio-Medico, Rome, Italy
| | - Bernhard Hess
- Internal Medicine and Nephrology, Klinik Im Park, Zurich, and University of Zurich, Zurich, Switzerland
| | - Giovanni Gambaro
- Renal Unit, Division of Nephrology and Dialysis, Department of Medicine, University of Verona, Verona, Italy
| | - Pietro Manuel Ferraro
- U.O.S. Terapia Conservativa della Malattia Renale Cronica, U.O.C. Nefrologia, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.,Università Cattolica del Sacro Cuore, Rome, Italy
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18
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Nephroplex: a kidney-focused NGS panel highlights the challenges of PKD1 sequencing and identifies a founder BBS4 mutation. J Nephrol 2021; 34:1855-1874. [PMID: 33964006 PMCID: PMC8610957 DOI: 10.1007/s40620-021-01048-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 04/04/2021] [Indexed: 12/02/2022]
Abstract
Background Genetic testing of patients with inherited kidney diseases has emerged as a tool of clinical utility by improving the patients’ diagnosis, prognosis, surveillance and therapy. Methods The present study applied a Next Generation Sequencing (NGS)-based panel, named NephroPlex, testing 115 genes causing renal diseases, to 119 individuals, including 107 probands and 12 relatives. Thirty-five (poly)cystic and 72 non (poly)cystic individuals were enrolled. The latter subgroup of patients included Bardet-Biedl syndrome (BBS) patients, as major components. Results Disease-causing mutations were identified in 51.5 and 40% of polycystic and non-polycystic individuals, respectively. Autosomal dominant polycystic kidney disease (ADPKD) patients with truncating PKD1 variants showed a trend towards a greater slope of the age-estimated glomerular filtration rate (eGFR) regression line than patients with (i) missense variants, (ii) any PKD2 mutations and (iii) no detected mutations, according to previous findings. The analysis of BBS individuals showed a similar frequency of BBS4,9,10 and 12 mutations. Of note, all BBS4-mutated patients harbored the novel c.332+1G>GTT variant, which was absent in public databases, however, in our internal database, an additional heterozygote carrier was found. All BBS4-mutated individuals originated from the same geographical area encompassing the coastal provinces of Naples. Discussion In conclusion, these findings indicate the potential for a genetic panel to provide useful information at both clinical and epidemiological levels. Graphic abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1007/s40620-021-01048-4.
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19
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Trepiccione F, Walsh SB, Ariceta G, Boyer O, Emma F, Camilla R, Ferraro PM, Haffner D, Konrad M, Levtchenko E, Lopez-Garcia SC, Santos F, Stabouli S, Szczepanska M, Tasic V, Topaloglu R, Vargas-Poussou R, Wlodkowski T, Bockenhauer D. Distal Renal Tubular Acidosis: ERKNet/ESPN Clinical Practice Points. Nephrol Dial Transplant 2021; 36:1585-1596. [PMID: 33914889 DOI: 10.1093/ndt/gfab171] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Indexed: 12/15/2022] Open
Abstract
Distal renal tubular acidosis (dRTA) is characterised by an impaired ability of the distal tubule to excrete acid, leading to metabolic acidosis. Associated complications include bone disease, growth failure, urolithiasis and hypokalaemia. Due to its rarity, there is a limited evidence to guide diagnosis and management, however, available data strongly suggest that metabolic control of the acidosis by alkali supplementation can halt or revert almost all complications. Despite this, cohort studies show that adequate metabolic control is present in only about half of patients, highlighting problems with treatment provision or adherence. With these clinical practice points the authors, part of the working groups tubulopathies in the European Rare Kidney Disease Reference network (ERKnet) and inherited kidney diseases of the European Society for Paediatric Nephrology (ESPN) aim to provide guidance for the management of patients with dRTA to facilitate adequate treatment and establish an initial best practice standard against which treatment of patients can be audited.
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Affiliation(s)
- Francesco Trepiccione
- Department of Translational Medical Sciences, University of Campania "L. Vanvitelli", Naples, Italy
| | - Steven B Walsh
- Department of Renal Medicine, University College London, UK
| | - Gema Ariceta
- Division of Pediatric Nephrology. Hospital Universitario Vall d' Hebron. Universitat Autonoma de Barcelona. Barcelona, Spain
| | - Olivia Boyer
- Pediatric Nephrology, Necker Hospital, APHP, MARHEA, Imagine Institute, Paris University, Paris, France
| | - Francesco Emma
- Division of Nephrology, Bambino Gesu Children's Hospital - IRCCS, Rome, Italy
| | - Roberta Camilla
- Nephrology, Dialysis, Transplantation, Regina Margherita University Hospital, Turin, Italy
| | - Pietro Manuel Ferraro
- U.O.S. Terapia Conservativa della Malattia Renale Cronica, U.O.C. Nefrologia, Dipartimento di Scienze Mediche e Chirurgiche, Fondazione Policlinico Universitario A. Gemelli IRCCS, Roma, Italy.,Dipartimento Universitario di Medicina e Chirurgia Traslazionale, Università Cattolica del Sacro Cuore, Roma, Italy
| | - Dieter Haffner
- Department of Pediatric Kidney, Liver and Metabolic Diseases, Hannover Medical School Children's Hospital, Hannover, Germany
| | - Martin Konrad
- Department of General Pediatrics, University Children's Hospital, Muenster, Germany
| | - Elena Levtchenko
- Division of Pediatric Nephrology, University Hospitals Leuven; Department of Development & Regeneration, Katholieke Universiteit Leuven, Belgium
| | - Sergio Camilo Lopez-Garcia
- Department of Renal Medicine, University College London, UK.,Renal Unit, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK
| | - Fernando Santos
- Department of Pediatrics, Hospital Universitario Central de Asturias and Área de Pediatría, Dpto. de Medicina, Universidad de Oviedo, Oviedo, Spain
| | - Stella Stabouli
- 1st Department of Pediatrics, Aristotle University, Thessaloniki, Greece
| | | | - Velibor Tasic
- University Children's Hospital, Medical School, Skopje, Macedonia
| | - Rezan Topaloglu
- Department of Pediatric Nephrology, Hacettepe University Faculty of Medicine, Hacettepe University, Ankara, Turkey
| | - Rosa Vargas-Poussou
- Department of Genetics, Centre de Références MARHEA, Hôpital Européen Georges Pompidou Assistance Publique Hôpitaux de Paris, Paris France
| | - Tanja Wlodkowski
- Department of Paediatric Nephrology, University Children's Hospital, Heidelberg, Germany
| | - Detlef Bockenhauer
- Department of General Pediatrics, University Children's Hospital, Muenster, Germany.,Division of Pediatric Nephrology, University Hospitals Leuven; Department of Development & Regeneration, Katholieke Universiteit Leuven, Belgium
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20
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Khandelwal P, Mahesh V, Mathur VP, Raut S, Geetha TS, Nair S, Hari P, Sinha A, Bagga A. Phenotypic variability in distal acidification defects associated with WDR72 mutations. Pediatr Nephrol 2021; 36:881-887. [PMID: 33033857 DOI: 10.1007/s00467-020-04747-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 07/21/2020] [Accepted: 08/26/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Distal renal tubular acidosis (RTA) is typically caused by defects in ATP6V0A4, ATP6V1B1, and SLC4A1, accounting for 60-80% of patients. Genes recently implicated include FOXI1, ATP6V1C2, and WDR72, of which WDR72 is associated with dental enamel defects. METHODS We describe 4 patients, from three unrelated consanguineous families, with RTA and amelogenesis imperfecta. Distal tubular acidification was evaluated by furosemide-fludrocortisone test, urine-to-blood PCO2 gradient and fractional excretion of bicarbonate. Exome sequencing was performed using a panel of genes implicated in human disease. RESULTS Patients had polyuria, hypokalemia, hypercalciuria, and nephrocalcinosis, but metabolic acidosis varied in severity. Although all patients acidified urine to pH < 5.3 during furosemide-fludrocortisone test, urine-to-blood PCO2 gradient was < 20 mmHg during bicarbonate loading. All patients had transient proximal tubular dysfunction with urinary losses of phosphate and beta-2-microglobulin, and generalized aminoaciduria. Homozygous pathogenic truncating variants in WDR72 was detected in all probands. CONCLUSION Patients with WDR72 mutations show mild rate-dependent distal RTA with variable metabolic acidosis, and intact ability to acidify the urine on provocative testing. Concomitant proximal tubular dysfunction may be present. Mutations in WDR72 should be considered in patients with suspected distal RTA, especially if associated with dental defects.
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Affiliation(s)
- Priyanka Khandelwal
- Division of Nephrology, Department of Pediatrics, ICMR Center for Advanced Research in Nephrology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Mahesh V
- Division of Nephrology, Department of Pediatrics, ICMR Center for Advanced Research in Nephrology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Vijay Prakash Mathur
- Center for Dental Education and Research, All India Institute of Medical Sciences, New Delhi, India
| | - Sumantra Raut
- Division of Nephrology, Department of Pediatrics, ICMR Center for Advanced Research in Nephrology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | | | | | - Pankaj Hari
- Division of Nephrology, Department of Pediatrics, ICMR Center for Advanced Research in Nephrology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Aditi Sinha
- Division of Nephrology, Department of Pediatrics, ICMR Center for Advanced Research in Nephrology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India.
| | - Arvind Bagga
- Division of Nephrology, Department of Pediatrics, ICMR Center for Advanced Research in Nephrology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
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21
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Giglio S, Montini G, Trepiccione F, Gambaro G, Emma F. Distal renal tubular acidosis: a systematic approach from diagnosis to treatment. J Nephrol 2021; 34:2073-2083. [PMID: 33770395 PMCID: PMC8610947 DOI: 10.1007/s40620-021-01032-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 03/16/2021] [Indexed: 12/03/2022]
Abstract
Renal tubular acidosis (RTA) comprises a group of disorders in which excretion of hydrogen ions or reabsorption of filtered HCO3 is impaired, leading to chronic metabolic acidosis with normal anion gap. In the current review, the focus is placed on the most common type of RTA, Type 1 RTA or Distal RTA (dRTA), which is a rare chronic genetic disorder characterized by an inability of the distal nephron to secrete hydrogen ions in the presence of metabolic acidosis. Over the years, knowledge of the molecular mechanisms behind acid secretion has improved, thereby greatly helping the diagnosis of dRTA. The primary or inherited form of dRTA is mostly diagnosed in infancy, childhood, or young adulthood, while the acquired secondary form, as a consequence of other disorders or medications, can happen at any age, although it is more commonly seen in adults. dRTA is not as “benign” as previously assumed, and can have several, highly variable long-term consequences. The present review indeed reports and summarizes both clinical symptoms and diagnosis, long-term outcomes, genetic inheritance, epidemiology and current treatment options, with the aim of shedding more light onto this rare disorder. Being a chronic condition, dRTA also deserves attention in the transition between pediatric and adult nephrology care, and as a rare disease it has a place in the European and Italian rare nephrological diseases network.
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Affiliation(s)
- Sabrina Giglio
- Medical Genetics Unit, Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy.
| | - Giovanni Montini
- Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Nephrology, Dialysis and PediatricTransplant Unit, Milan, Italy.,Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Francesco Trepiccione
- Department of Translational Medical Sciences, University of Campania "L. Vanvitelli", Naples, Italy.,Biogem Research Institute Ariano Irpino, Ariano Irpino, Italy
| | - Giovanni Gambaro
- Nephrology Department of Medicine, University of Verona, Verona, Italy
| | - Francesco Emma
- Division of Nephrology, Department of Pediatric Subspecialties, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
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22
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Palmer BF, Kelepouris E, Clegg DJ. Renal Tubular Acidosis and Management Strategies: A Narrative Review. Adv Ther 2021; 38:949-968. [PMID: 33367987 PMCID: PMC7889554 DOI: 10.1007/s12325-020-01587-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 11/26/2020] [Indexed: 12/29/2022]
Abstract
Renal tubular acidosis (RTA) occurs when the kidneys are unable to maintain normal acid−base homeostasis because of tubular defects in acid excretion or bicarbonate ion reabsorption. Using illustrative clinical cases, this review describes the main types of RTA observed in clinical practice and provides an overview of their diagnosis and treatment. The three major forms of RTA are distal RTA (type 1; characterized by impaired acid excretion), proximal RTA (type 2; caused by defects in reabsorption of filtered bicarbonate), and hyperkalemic RTA (type 4; caused by abnormal excretion of acid and potassium in the collecting duct). Type 3 RTA is a rare form of the disease with features of both distal and proximal RTA. Accurate diagnosis of RTA plays an important role in optimal patient management. The diagnosis of distal versus proximal RTA involves assessment of urinary acid and bicarbonate secretion, while in hyperkalemic RTA, selective aldosterone deficiency or resistance to its effects is confirmed after exclusion of other causes of hyperkalemia. Treatment options include alkali therapy in patients with distal or proximal RTA and lowering of serum potassium concentrations through dietary modification and potential new pharmacotherapies in patients with hyperkalemic RTA including newer potassium binders.
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23
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Kallistrou E, Architha NN, Pal SK, Oyibo SO. Severe Hypokalemia Secondary to Transient Distal Renal Tubular Acidosis in a Previously Healthy Woman. Cureus 2021; 13:e12765. [PMID: 33500865 PMCID: PMC7817551 DOI: 10.7759/cureus.12765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Normal anion gap (non-gap) hyperchloremic acidosis with hypokalemia is a medical emergency. There are several causes of this metabolic phenomenon, of which distal renal tubular acidosis is among the very rare causes. In this report, we present an unusual case of a previously healthy woman who was admitted to the intensive care unit with a short history of severe muscle weakness. She had no significant past medical history and was not taking any regular medication. There was also no history of recent drug or herb ingestion. Investigations demonstrated a combination of severe hypokalemia, hyperchloremia, hypobicarbonatemia (non-gap metabolic acidosis), and relatively raised urinary potassium and urinary pH in the presence of severe hypokalemia and metabolic acidosis. Results suggested a diagnosis of distal renal tubular acidosis. The patient responded rapidly to a short course of electrolyte replacement therapy and the condition resolved spontaneously thereafter. This case highlights the fact that distal renal tubular acidosis can occur as a transient phenomenon in previously healthy individuals.
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Affiliation(s)
| | | | - Soubhik K Pal
- Nephrology, Peterborough City Hospital, Peterborough, GBR
| | - Samson O Oyibo
- Diabetes and Endocrinology, Peterborough City Hospital, Peterborough, GBR
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Boro H, Khatiwada S, Alam S, Kubihal S, Dogra V, Mannar V, Khadgawat R. Renal Tubular Acidosis Manifesting as Severe Metabolic Bone Disease. EUROPEAN ENDOCRINOLOGY 2021. [DOI: 10.17925/ee.2021.1.1.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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25
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Viering DHHM, Bech AP, de Baaij JHF, Steenbergen EJ, Danser AHJ, Wetzels JFM, Bindels RJM, Deinum J. Functional tests to guide management in an adult with loss of function of type-1 angiotensin II receptor. Pediatr Nephrol 2021; 36:2731-2737. [PMID: 33768328 PMCID: PMC8370907 DOI: 10.1007/s00467-021-05018-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 02/04/2021] [Accepted: 02/17/2021] [Indexed: 11/30/2022]
Abstract
BACKGROUND Genetic loss of function of AGT (angiotensinogen), REN (renin), ACE (angiotensin-converting enzyme), or AGTR1 (type-1 angiotensin II receptor) leads to renal tubular dysgenesis (RTD). This syndrome is almost invariably lethal. Most surviving patients reach stage 5 chronic kidney disease at a young age. METHODS Here, we report a 28-year-old male with a homozygous truncating mutation in AGTR1 (p.Arg216*), who survived the perinatal period with a mildly impaired kidney function. In contrast to classic RTD, kidney biopsy showed proximal tubules that were mostly normal. During the subsequent three decades, we observed evidence of both tubular dysfunction (hyperkalemia, metabolic acidosis, salt-wasting and a urinary concentrating defect) and glomerular dysfunction (reduced glomerular filtration rate, currently ~30 mL/min/1.73 m2, accompanied by proteinuria). To investigate the recurrent and severe hyperkalemia, we performed a patient-tailored functional test and showed that high doses of fludrocortisone induced renal potassium excretion by 155%. Furthermore, fludrocortisone lowered renal sodium excretion by 39%, which would have a mitigating effect on salt-wasting. In addition, urinary pH decreased in response to fludrocortisone. Opposite effects on urinary potassium and pH occurred with administration of amiloride, further supporting the notion that a collecting duct is present and able to react to fludrocortisone. CONCLUSIONS This report provides living proof that even truncating loss-of-function mutations in AGTR1 are compatible with life and relatively good GFR and provides evidence for the prescription of fludrocortisone to treat hyperkalemia and salt-wasting in such patients.
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Affiliation(s)
- Daan H. H. M. Viering
- grid.10417.330000 0004 0444 9382Department of Physiology, Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Nijmegen, the Netherlands
| | - Anneke P. Bech
- grid.415930.aDepartment of Nephrology, Rijnstate, Arnhem, the Netherlands
| | - Jeroen H. F. de Baaij
- grid.10417.330000 0004 0444 9382Department of Physiology, Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Nijmegen, the Netherlands
| | - Eric J. Steenbergen
- grid.10417.330000 0004 0444 9382Department of Pathology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - A. H. Jan Danser
- grid.5645.2000000040459992XDepartment of Internal Medicine, Erasmus Medical Centre, Rotterdam, the Netherlands
| | - Jack F. M. Wetzels
- grid.10417.330000 0004 0444 9382Department of Nephrology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - René J. M. Bindels
- grid.10417.330000 0004 0444 9382Department of Physiology, Radboud University Medical Centre, Radboud Institute for Molecular Life Sciences, Nijmegen, the Netherlands
| | - Jaap Deinum
- Department of Internal Medicine, Radboud University Medical Centre, Huispost 463, Geert Grooteplein 8, 6525, GA, Nijmegen, the Netherlands.
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Alonso‐Varela M, Gil‐Peña H, Santos F. Incomplete distal renal tubular acidosis in children. Acta Paediatr 2020; 109:2243-2250. [PMID: 32212394 DOI: 10.1111/apa.15269] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/08/2020] [Accepted: 03/19/2020] [Indexed: 12/15/2022]
Abstract
AIM To describe incomplete distal renal tubular acidosis (iDRTA) in paediatric patients, a term used for the diagnosis of patients who do not develop spontaneous overt metabolic acidosis but are unable to acidify the urine in response to an ammonium chloride load. METHODS Tests used to explore urinary acidification were revised. In addition, publications in English extracted from 161 entries yielded by a PubMed database search, using 'incomplete distal renal tubular acidosis' as keyword, were reviewed. RESULTS Incomplete distal renal tubular acidosis has mostly been identified in adults with autoimmune diseases, nephrolithiasis, nephrocalcinosis and/or osteopenia. iDRTA has been reported in few paediatric patients with rickets, congenital abnormalities of kidney and urological tract and/or growth failure. The pathophysiological mechanisms potentially responsible for the defect of urinary acidification are discussed as well as the clinical and biochemical findings of iDRTA described in children. CONCLUSION The presentation of iDRTA in children differs from adults. The clinical and biochemical features of iDRTA are not well characterised in paediatric patients. The detection of iDRTA in groups of population such as heterozygous carriers of primary DRTA gene mutations and children with hypocitraturia or hypercalciuria might be of clinical interest to better know the pathophysiology and natural history of iDRTA.
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Affiliation(s)
- Marta Alonso‐Varela
- Hospital Universitario Cruces Baracaldo, Vizcaya Spain
- University of Oviedo Oviedo Spain
| | | | - Fernando Santos
- University of Oviedo Oviedo Spain
- Hospital Universitario Central de Asturias Oviedo Spain
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Abstract
Renal tubular acidosis (RTA) comprises a group of disorders characterized by low capacity for net acid excretion and persistent hyperchloremic metabolic acidosis, despite preserved glomerular filtration rate. RTA are classified into chiefly three types (1, 2 and 4) based on pathophysiology and clinical and laboratory characteristics. Most patients have primary RTA that presents in infancy with polyuria, growth retardation, rickets and/or hypotonia. Diagnosis requires careful evaluation, including exclusion of other entities that can cause acidosis. A variety of tests, administered stepwise, are useful for the diagnosis and characterization of RTA. A genetic or acquired basis can be determined in majority of patients through focused evaluation. Management involves correction of acidosis and dyselectrolytemia; patients with proximal RTA with Fanconi syndrome and rickets require additional supplements of phosphate and vitamin D.
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Affiliation(s)
- Arvind Bagga
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Aditi Sinha
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, 110029, India
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Chanchlani R, Nemer P, Sinha R, Nemer L, Krishnappa V, Sochett E, Safadi F, Raina R. An Overview of Rickets in Children. Kidney Int Rep 2020; 5:980-990. [PMID: 32647755 PMCID: PMC7335963 DOI: 10.1016/j.ekir.2020.03.025] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 03/03/2020] [Accepted: 03/27/2020] [Indexed: 12/13/2022] Open
Abstract
Rickets is a common bone disease worldwide that is associated with disturbances in calcium and phosphate homeostasis and can lead to short stature and joint deformities. Rickets can be diagnosed based on history and physical examination, radiological features, and biochemical tests. It can be classified into 2 major groups based on phosphate or calcium levels: phosphopenic and calcipenic. Knowledge of categorization of the type of rickets is essential for prompt diagnosis and proper management. Nutritional rickets is a preventable disease through adequate intake of vitamin D through both dietary and sunlight exposure. There are other subtypes of rickets, such as vitamin D-dependent type 1 rickets and vitamin D-dependent type 2 rickets (due to defects in vitamin D metabolism), renal rickets (due to poor kidney function), and hypophosphatemic rickets (vitamin D-resistant rickets secondary to renal phosphate wasting wherein fibroblast growth factor-23 (FGF-23) often plays a major role), which requires closer monitoring and supplementation with activated vitamin D with or without phosphate supplements. An important development has been the introduction of burosumab, a human monoclonal antibody to FGF-23, which is approved for the treatment of X-linked hypophosphatemia among children 1 year and older.
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Affiliation(s)
- Rahul Chanchlani
- Division of Pediatric Nephrology, Department of Pediatrics, McMaster Children’s Hospital, Hamilton, Ontario, Canada
- Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, Canada
| | - Paul Nemer
- Akron Nephrology Associates/Cleveland Clinic Akron General, Akron, Ohio, USA
| | - Rajiv Sinha
- Division of Pediatric Nephrology, Institute of Child Health, Kolkata, India
| | - Lena Nemer
- Akron Nephrology Associates/Cleveland Clinic Akron General, Akron, Ohio, USA
| | - Vinod Krishnappa
- Akron Nephrology Associates/Cleveland Clinic Akron General, Akron, Ohio, USA
- Department of Public Health, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Etienne Sochett
- Division of Pediatrics Endocrinology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Fayez Safadi
- Department of Anatomy and Neurobiology, Northeast Ohio Medical University, Rootstown, Ohio, USA
- Rebecca D. Considine Research Institute, Akron Children Hospital, Akron, Ohio, USA
| | - Rupesh Raina
- Akron Nephrology Associates/Cleveland Clinic Akron General, Akron, Ohio, USA
- Department of Nephrology, Akron Children’s Hospital, Akron, Ohio, USA
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29
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Bertocchio JP, Genetet S, Da Costa L, Walsh SB, Knebelmann B, Galimand J, Bessenay L, Guitton C, De Lafaille R, Vargas-Poussou R, Eladari D, Mouro-Chanteloup I. Red Blood Cell AE1/Band 3 Transports in Dominant Distal Renal Tubular Acidosis Patients. Kidney Int Rep 2020; 5:348-357. [PMID: 32154456 PMCID: PMC7056926 DOI: 10.1016/j.ekir.2019.12.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 11/26/2019] [Accepted: 12/31/2019] [Indexed: 11/30/2022] Open
Abstract
Introduction Anion exchanger 1 (AE1) (SLC4A1 gene product) is a membrane protein expressed in both kidney and red blood cells (RBCs): it exchanges extracellular bicarbonate (HCO3–) for intracellular chloride (Cl–) and participates in acid−base homeostasis. AE1 mutations in kidney α-intercalated cells can lead to distal renal tubular acidosis (dRTA). In RBC, AE1 (known as band 3) is also implicated in membrane stability: deletions can cause South Asian ovalocytosis (SAO). Methods We retrospectively collected clinical and biological data from patients harboring dRTA due to a SLC4A1 mutation and analyzed HCO3– and Cl– transports (by stopped-flow spectrophotometry) and expression (by flow cytometry, fluorescence activated cell sorting, and Coomassie blue staining) in RBCs, as well as RBC membrane stability (ektacytometry). Results Fifteen patients were included. All experience nephrolithiasis and/or nephrocalcinosis, 2 had SAO and dRTA (dRTA SAO+), 13 dominant dRTA (dRTA SAO−). The latter did not exert specific RBC membrane anomalies. Both HCO3– and Cl– transports were lower in patients with dRTA SAO+ than in those with dRTA SAO− or controls. Using 3 different extracellular probes, we report a decreased expression (by 52%, P < 0.05) in dRTA SAO+ patients by fluorescence activated cell sorting, whereas total amount of protein was not affected. Conclusion Band 3 transport function and expression in RBCs from dRTA SAO− patients is normal. However, in SAO RBCs, impaired conformation of AE1/band 3 corresponds to an impaired function. Thus, the driver of acid−base defect during dominant dRTA is probably an impaired membrane expression.
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Affiliation(s)
- Jean-Philippe Bertocchio
- Renal and Metabolic Diseases Unit, Assistance Publique-Hôpitaux de Paris, European Georges Pompidou Hospital, Paris, France.,Faculty of Medicine, Paris Descartes University, Paris, France.,Reference Center for Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Genito-urinary Medical Oncology and Research Department, MD Anderson Cancer Center, Houston, Texas, USA
| | - Sandrine Genetet
- UMR_S1134, Integrated Red Globule Biology (IRGB), Inserm, University of Paris, Paris, France.,Team 1, Physiology of Normal and Pathologic Red Blood Cell, Institut National de la Transfusion Sanguine (INTS), Paris, France
| | - Lydie Da Costa
- UMR_S1134, Integrated Red Globule Biology (IRGB), Inserm, University of Paris, Paris, France.,UMR_S1134, Inserm, Paris, France.,Service d'Hématologie Biologique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Stephen B Walsh
- Department of Renal Medicine, University College of London, London, UK
| | - Bertrand Knebelmann
- Nephrology Department, Assistance Publique-Hôpitaux de Paris, Necker-Enfants Malades Hospital, Paris, France
| | - Julie Galimand
- Service d'Hématologie Biologique, Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Paris, France
| | - Lucie Bessenay
- Pediatrics Department, University Hospital of Clermont-Ferrand, Clermont-Ferrand, France
| | - Corinne Guitton
- Pediatrics Department, Assistance Publique-Hôpitaux de Paris, Hôpital Bicêtre, Le Kremlin Bicêtre, France
| | - Renaud De Lafaille
- Nephrology Department, University Hospital of Bordeaux, Bordeaux, Aquitaine, France
| | - Rosa Vargas-Poussou
- Reference Center for Maladies Rénales Héréditaires de l'Enfant et de l'Adulte (MARHEA), Paris, France.,Institut National pour la Santé et la Recherche Médicale (INSERM), Unité Mixte de Recherche UMRS1138, Cordeliers Research Center, Paris, France.,Genetics Department, Assistance Publique-Hôpitaux de Paris, European Georges Pompidou Hospital, Paris, France
| | - Dominique Eladari
- Renal and Metabolic Diseases Department, CHU de la Réunion, Felix Guyon Hospital, Saint Denis, France.,INSERM, UMRS 1283-European Genomic Institute for Diabetes, Lille, France
| | - Isabelle Mouro-Chanteloup
- UMR_S1134, Integrated Red Globule Biology (IRGB), Inserm, University of Paris, Paris, France.,Team 1, Physiology of Normal and Pathologic Red Blood Cell, Institut National de la Transfusion Sanguine (INTS), Paris, France
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30
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García-Nieto VM, Claverie-Martín F, Perdomo-Ramírez A, Cárdoba-Lanus E, Ramos-Trujillo E, Mura-Escorche G, Tejera-Carreño P, Luis-Yanes MI. Consideraciones acerca de las bases moleculares de algunas tubulopatías en relación con la endogamia y los desplazamientos poblacionales. Nefrologia 2020; 40:126-132. [DOI: 10.1016/j.nefro.2019.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 07/26/2019] [Accepted: 08/06/2019] [Indexed: 02/08/2023] Open
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Cazenave M, Audard V, Bertocchio JP, Habibi A, Baron S, Prot-Bertoye C, Berkenou J, Maruani G, Stehlé T, Cornière N, Ayari H, Friedlander G, Galacteros F, Houillier P, Bartolucci P, Courbebaisse M. Tubular Acidification Defect in Adults with Sickle Cell Disease. Clin J Am Soc Nephrol 2020; 15:16-24. [PMID: 31822527 PMCID: PMC6946065 DOI: 10.2215/cjn.07830719] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 10/29/2019] [Indexed: 12/28/2022]
Abstract
BACKGROUND AND OBJECTIVES Metabolic acidosis is a frequent manifestation of sickle cell disease but the mechanisms and determinants of this disorder are unknown. Our aim was to characterize urinary acidification capacity in adults with sickle cell disease and to identify potential factors associated with decreased capacity to acidify urine. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Among 25 adults with sickle cell disease and an eGFR of ≥60 ml/min per 1.73 m2 from a single center in France, we performed an acute acidification test after simultaneous administration of furosemide and fludrocortisone. A normal response was defined as a decrease in urinary pH <5.3 and an increase in urinary ammonium excretion ≥33 µEq/min at one or more of the six time points after furosemide and fludrocortisone administration. RESULTS Of the participants (median [interquartile range] age of 36 [24-43] years old, 17 women), 12 had a normal and 13 had an abnormal response to the test. Among these 13 participants, nine had normal baseline plasma bicarbonate concentration. Plasma aldosterone was within the normal range for all 13 participants with an abnormal response, making the diagnosis of type 4 tubular acidosis unlikely. The participants with an abnormal response to the test were significantly older, more frequently treated with oral bicarbonate, had a higher plasma uric acid concentration, higher hemolysis activity, lower eGFR, lower baseline plasma bicarbonate concentration, higher urine pH, lower urine ammonium ion excretion, and lower fasting urine osmolality than those with a normal response. Considering both groups, the maximum urinary ammonium ion excretion was positively correlated with fasting urine osmolality (r 2=0.34, P=0.002), suggesting that participants with sickle cell disease and lower urine concentration capacity have lower urine acidification capacity. CONCLUSIONS Among adults with sickle cell disease, impaired urinary acidification capacity attributable to distal tubular dysfunction is common and associated with the severity of hyposthenuria. PODCAST This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_12_10_CJN07830719.mp3.
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Affiliation(s)
- Maud Cazenave
- Nephrology and Renal Transplantation Department, Pitié-Salpetrière Hospital, Assistance Publique-Hôpitaux de Paris (AP-HP), Sorbonne University, Paris, France
| | - Vincent Audard
- Nephrology and Renal Transplantation Department, Institut National de la Santé et de la Recherche Médicale (INSERM) U955, Henri Mondor Hospital, AP-HP, Paris Est Créteil University, Créteil, France
| | - Jean-Philippe Bertocchio
- Physiology Department, European Georges Pompidou University Hospital, AP-HP, Paris Descartes University, INSERM U1138, Centre National de la Recherche Scientifique (CNRS) ERL8228, Paris, France
| | - Anoosha Habibi
- Sickle Cell Referral Center, Internal Medicine Unit, IMRB team 2, UPEC, Labex GRex, Henri Mondor Hospital, AP-HP, Créteil, France
| | - Stéphanie Baron
- Physiology Department, European Georges Pompidou University Hospital, AP-HP, Paris Descartes University, INSERM U1138, Centre National de la Recherche Scientifique (CNRS) ERL8228, Paris, France
| | - Caroline Prot-Bertoye
- Physiology Department, European Georges Pompidou University Hospital, AP-HP, Paris Descartes University, INSERM U1138, Centre National de la Recherche Scientifique (CNRS) ERL8228, Paris, France
| | - Jugurtha Berkenou
- Sickle Cell Referral Center, Internal Medicine Unit, IMRB team 2, UPEC, Labex GRex, Henri Mondor Hospital, AP-HP, Créteil, France
| | - Gérard Maruani
- Physiology Department, European Georges Pompidou University Hospital, AP-HP, Paris Descartes University, Necker-Enfants Malades Institute, INSERM U1151-CNRS UMR8253, Paris, France; and
| | - Thomas Stehlé
- Nephrology and Renal Transplantation Department, Institut National de la Santé et de la Recherche Médicale (INSERM) U955, Henri Mondor Hospital, AP-HP, Paris Est Créteil University, Créteil, France
| | - Nicolas Cornière
- Nephrology Department, Felix Guyon Hospital, Saint-Denis, Réunion Island, France
| | - Hamza Ayari
- Physiology Department, European Georges Pompidou University Hospital, AP-HP, Paris Descartes University, INSERM U1138, Centre National de la Recherche Scientifique (CNRS) ERL8228, Paris, France
| | - Gérard Friedlander
- Physiology Department, European Georges Pompidou University Hospital, AP-HP, Paris Descartes University, Necker-Enfants Malades Institute, INSERM U1151-CNRS UMR8253, Paris, France; and
| | - Frédéric Galacteros
- Sickle Cell Referral Center, Internal Medicine Unit, IMRB team 2, UPEC, Labex GRex, Henri Mondor Hospital, AP-HP, Créteil, France
| | - Pascal Houillier
- Physiology Department, European Georges Pompidou University Hospital, AP-HP, Paris Descartes University, INSERM U1138, Centre National de la Recherche Scientifique (CNRS) ERL8228, Paris, France
| | - Pablo Bartolucci
- Sickle Cell Referral Center, Internal Medicine Unit, IMRB team 2, UPEC, Labex GRex, Henri Mondor Hospital, AP-HP, Créteil, France
| | - Marie Courbebaisse
- Physiology Department, European Georges Pompidou University Hospital, AP-HP, Paris Descartes University, Necker-Enfants Malades Institute, INSERM U1151-CNRS UMR8253, Paris, France; and
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Kyono Y, Nozu K, Nakagawa T, Takami Y, Fujita H, Ioroi T, Kugo M, Iijima K, Kamiyoshi N. Combination of furosemide and fludrocortisone as a loading test for diagnosis of distal renal tubular acidosis in a pediatric case. CEN Case Rep 2019; 9:81-86. [PMID: 31705302 DOI: 10.1007/s13730-019-00432-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/27/2019] [Indexed: 11/26/2022] Open
Abstract
Renal tubular acidosis (RTA) is a rare disease caused by a defect of urinary acidification. The ammonium chloride loading test is the gold standard method for determining the type of RTA. However, because this test has some side effects (e.g., nausea, vomiting, and stomach discomfort), applying this test for pediatric cases is difficult. Recently, a loading test with the combination of furosemide and fludrocortisone was reported to be an alternative to the ammonium chloride loading test, with 100% sensitivity and specificity in adult's cases. We report the first pediatric case of distal RTA in a patient who was successfully diagnosed by a drug loading test with the combination of furosemide and fludrocortisone without any side effects. We also performed genetic analysis and detected a known pathogenic variant in the SLC4A1 gene. The combination loading test of furosemide and fludrocortisone is a useful and safe diagnostic tool for pediatric cases of RTA.
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Affiliation(s)
- Yuki Kyono
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe, Hyogo, 650-0017, Japan
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe, Hyogo, 650-0017, Japan
| | - Taku Nakagawa
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Yuichi Takami
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Hideki Fujita
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Tomoaki Ioroi
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Masaaki Kugo
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan
| | - Kazumoto Iijima
- Department of Pediatrics, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Kobe, Hyogo, 650-0017, Japan
| | - Naohiro Kamiyoshi
- Department of Pediatrics, Japanese Red Cross Society Himeji Hospital, 1-12-1 Shimoteno, Himeji, Hyogo, 670-8540, Japan.
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Sidler M, Mohebbi N, Hoorn EJ, Wagner CA. Gut It Out: Laxative Abuse Mimicking Distal Renal Tubular Acidosis. Kidney Blood Press Res 2019; 44:1294-1299. [PMID: 31480048 DOI: 10.1159/000501855] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/01/2019] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Distal renal tubular acidosis (dRTA) can be inherited or acquired. CASE PRESENTATION Here, we describe the case of a 45-year-old female patient with non-anion gap metabolic acidosis, hypokalemia, and alkaline urine. She had a history of rheumatoid arthritis and kidney stones and failed to acidify urine upon the fludrocortisone and furosemide test. Therefore, the diagnosis of dRTA secondary to an autoimmune disease was made. A kidney biopsy was examined for markers of acid-secretory intercalated cells. Surprisingly, no obvious difference in the relative number of acid-secretory intercalated cells or in the distribution of major proteins involved in acid secretion was found. Furthermore, increasing doses of potassium citrate failed to correct the hypokalemia and acidosis. Since these findings were rather atypical for autoimmune dRTA, alternative causes of her hypokalemia and metabolic acidosis were sought. The patient was found to chronically consume laxatives, which can also cause kidney stones and may result in a false-positive urinary acidification test. CONCLUSION Chronic laxative abuse may mimic dRTA and should therefore be considered in unexplained hypokalemia with non-anion gap metabolic acidosis.
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Affiliation(s)
- Marius Sidler
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Ewout J Hoorn
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland,
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Abstract
Metabolic acidosis is defined as a pathologic process that, when unopposed, increases the concentration of hydrogen ions (H+) in the body and reduces the bicarbonate (HCO3-) concentration. Metabolic acidosis can be of a kidney origin or an extrarenal cause. Assessment of urinary ammonium excretion by calculating the urine anion gap or osmolal gap is a useful method to distinguish between these two causes. Extrarenal processes include increased endogenous acid production and accelerated loss of bicarbonate from the body. Metabolic acidosis of renal origin is due to a primary defect in renal acidification with no increase in extrarenal hydrogen ion production. This situation can occur because either the renal input of new bicarbonate is insufficient to regenerate the bicarbonate lost in buffering endogenous acid as with distal renal tubular acidosis (RTA) or the RTA of renal insufficiency, or the filtered bicarbonate is lost by kidney wasting as in proximal RTA. In either condition, because of loss of either NaHCO3 (proximal RTA) or NaA (distal RTA), effective extracellular volume is reduced and as a result the avidity for chloride reabsorption derived from the diet is increased and results in a hyperchloremic normal gap metabolic acidosis. The RTA of renal insufficiency is also characterized by a normal gap acidosis, however, with severe reductions in the glomerular filtration rate an anion gap metabolic acidosis eventually develops.
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Affiliation(s)
- Biff F Palmer
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA -
| | - Deborah J Clegg
- Department of Health Studies, College of Arts and Sciences, American University, Washington, DC, USA.,Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, University of California Los Angeles (UCLA), Los Angeles, CA, USA
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Prevalence of distal renal tubular acidosis in patients with calcium phosphate stones. World J Urol 2019; 38:789-794. [PMID: 31079188 DOI: 10.1007/s00345-019-02804-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 05/04/2019] [Indexed: 10/26/2022] Open
Abstract
INTRODUCTION AND PURPOSE Distal renal tubular acidosis (DRTA) is a metabolic disorder that associates urolithiasis and urinary pH > 6. The prevalence of DRTA in patients with calcium phosphate stones is not well known. The objective is to determine the prevalence of DRTA in patients with calcium phosphate stones and urinary pH above 6 based on the furosemide test. METHODS A total of 54 patients with calcium phosphate stones and urinary pH above 6.0 were submitted to the furosemide test. The association of DRTA with age, sex, type of stone, stone recurrence, stone bilaterality, 24-h urine biochemistry, and adverse effects of the furosemide test were examined. RESULTS The furosemide test indicated that 19 of 54 patients (35.2%) had DRTA. The sex ratio was similar in the two groups (p < 0.776). The DRTA group was significantly younger (p < 0.001), and had a higher prevalence of bilateral stones (p < 0.001), a higher prevalence of recurrent stones (p < 0.04), a lower plasma potassium level (p < 0.001), a higher urinary Ca level (p ≤ 0.05), and a lower urinary citrate level (p < 0.001). None of the patients reported adverse effects from the furosemide test. CONCLUSIONS There was a high prevalence of DTRA in patients with urinary pH above 6 and calcium phosphate stones. Young age, bilateral stones, stone recurrence, hypercalciuria, hypocitraturia, and plasma hypokalemia were associated with DRTA. None of the patients reported adverse effects of the furosemide test.
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Abstract
Renal tubular acidosis should be suspected in poorly thriving young children with hyperchloremic and hypokalemic normal anion gap metabolic acidosis, with/without syndromic features. Further workup is needed to determine the type of renal tubular acidosis and the presumed etiopathogenesis, which informs treatment choices and prognosis. The risk of nephrolithiasis and calcinosis is linked to the presence (proximal renal tubular acidosis, negligible stone risk) or absence (distal renal tubular acidosis, high stone risk) of urine citrate excretion. New formulations of slow-release alkali and potassium combination supplements are being tested that are expected to simplify treatment and lead to sustained acidosis correction.
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Affiliation(s)
- Robert Todd Alexander
- Department of Pediatrics and Physiology, Stollery Children's Hospital, 11405-87 Avenue, Edmonton, Alberta T6G 1C9, Canada
| | - Martin Bitzan
- Division of Nephrology, Department of Pediatrics, The Montreal Children's Hospital, McGill University Health Centre, Room B RC.6651, Montreal, Quebec H4A 3J1, Canada; Al Jalila Children's Hospital, Al Jadaf PO Box 7662, Dubai, UAE.
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Wang B, Wang-France J, Li H, Sansom SC. Furosemide reduces BK-αβ4-mediated K + secretion in mice on an alkaline high-K + diet. Am J Physiol Renal Physiol 2019; 316:F341-F350. [PMID: 30484346 DOI: 10.1152/ajprenal.00223.2018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Special high-K diets have cardioprotective effects and are often warranted in conjunction with diuretics such as furosemide for treating hypertension. However, it is not understood how a high-K diet (HK) influences the actions of diuretics on renal K+ handling. Furosemide acidifies the urine by increasing acid secretion via the Na+-H+ exchanger 3 (NHE3) in TAL and vacuolar H+-ATPase (V-ATPase) in the distal nephron. We previously found that an alkaline urine is required for large conductance Ca2+-activated K+ (BK)-αβ4-mediated K+ secretion in mice on HK. We therefore hypothesized that furosemide could reduce BK-αβ4-mediated K+ secretion by acidifying the urine. Treating with furosemide (drinking water) for 11 days led to decreased urine pH in both wild-type (WT) and BK-β4-knockout mice (BK-β4-KO) with increased V-ATPase expression and elevated plasma aldosterone levels. However, furosemide decreased renal K+ clearance and elevated plasma [K+] in WT but not BK-β4-KO. Western blotting and immunofluorescence staining showed that furosemide treatment decreased cortical expression of BK-β4 and reduced apical localization of BK-α in connecting tubules. Addition of the carbonic anhydrase inhibitor, acetazolamide, to furosemide water restored urine pH along with renal K+ clearance and plasma [K+] to control levels. Acetazolamide plus furosemide also restored the cortical expression of BK-β4 and BK-α in connecting tubules. These results indicate that in mice adapted to HK, furosemide reduces BK-αβ4-mediated K+ secretion by acidifying the urine.
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Affiliation(s)
- Bangchen Wang
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center , Omaha, Nebraska
| | - Jun Wang-France
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center , Omaha, Nebraska
| | - Huaqing Li
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center , Omaha, Nebraska
| | - Steven C Sansom
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center , Omaha, Nebraska
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Bech AP, Nijenhuis T, Wetzels JFM. Urine Acidification After Ammonium Chloride. Am J Kidney Dis 2018; 72:909-911. [PMID: 30297083 DOI: 10.1053/j.ajkd.2018.07.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 07/22/2018] [Indexed: 11/11/2022]
Affiliation(s)
- Anneke P Bech
- Department of Nephrology, Radboud University Medical Center, Nijmegen, the Netherlands.
| | - Tom Nijenhuis
- Department of Nephrology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Jack F M Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, the Netherlands
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Jain A, Srinivas BH, Emmanuel D, Jain VK, Parameshwaran S, Negi VS. Renal involvement in primary Sjogren’s syndrome: a prospective cohort study. Rheumatol Int 2018; 38:2251-2262. [DOI: 10.1007/s00296-018-4118-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/02/2018] [Indexed: 12/19/2022]
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Abstract
Distal renal tubular acidosis (DRTA) is defined as hyperchloremic, non-anion gap metabolic acidosis with impaired urinary acid excretion in the presence of a normal or moderately reduced glomerular filtration rate. Failure in urinary acid excretion results from reduced H+ secretion by intercalated cells in the distal nephron. This results in decreased excretion of NH4+ and other acids collectively referred as titratable acids while urine pH is typically above 5.5 in the face of systemic acidosis. The clinical phenotype in patients with DRTA is characterized by stunted growth with bone abnormalities in children as well as nephrocalcinosis and nephrolithiasis that develop as the consequence of hypercalciuria, hypocitraturia, and relatively alkaline urine. Hypokalemia is a striking finding that accounts for muscle weakness and requires continued treatment together with alkali-based therapies. This review will focus on the mechanisms responsible for impaired acid excretion and urinary potassium wastage, the clinical features, and diagnostic approaches of hypokalemic DRTA, both inherited and acquired.
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Abstract
Renal tubular acidosis (RTA) is comprised of a diverse group of congenital or acquired diseases with the common denominator of defective renal acid excretion with protean manifestation, but in adults, recurrent kidney stones and nephrocalcinosis are mainly found in presentation. Calcium phosphate (CaP) stones and nephrocalcinosis are frequently encountered in distal hypokalemic RTA type I. Alkaline urinary pH, hypocitraturia, and, less frequently, hypercalciuria are the tripartite lithogenic factors in distal RTA (dRTA) predisposing to CaP stone formation; the latter 2 are also commonly encountered in other causes of urolithiasis. Although the full blown syndrome is easily diagnosed by conventional clinical criteria, an attenuated forme fruste called incomplete dRTA typically evades clinical testing and is only uncovered by provocative acid-loading challenges. Stone formers (SFs) that cannot acidify urine of pH < 5.3 during acid loading are considered to have incomplete dRTA. However, urinary acidification capacity is not a dichotomous but rather a continuous trait, so incomplete dRTA is not a distinct entity but may be one end of a spectrum. Recent findings suggest that incomplete dRTA can be attributed to heterozygous carriers of hypofunctional V-ATPase. The value of incomplete dRTA diagnosis by provocative testing and genotyping candidate genes is a valuable research tool, but it remains unclear at the moment whether they alter clinical practice and needs further clarification. No randomized controlled trials have been performed in SFs with dRTA or CaP stones, and until such data are available, treatment of CaP stones are centered on reversing the biochemical abnormalities encountered in the metabolic workup. SFs with type I dRTA should receive alkali therapy, preferentially in the form of K-citrate delivered judiciously to treat the chronic acid retention that drives both stone formation and bone disease.
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Kurtz I. Renal Tubular Acidosis: H +/Base and Ammonia Transport Abnormalities and Clinical Syndromes. Adv Chronic Kidney Dis 2018; 25:334-350. [PMID: 30139460 PMCID: PMC6128697 DOI: 10.1053/j.ackd.2018.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Renal tubular acidosis (RTA) represents a group of diseases characterized by (1) a normal anion gap metabolic acidosis; (2) abnormalities in renal HCO3- absorption or new renal HCO3- generation; (3) changes in renal NH4+, Ca2+, K+, and H2O homeostasis; and (4) extrarenal manifestations that provide etiologic diagnostic clues. The focus of this review is to give a general overview of the pathogenesis of the various clinical syndromes causing RTA with a particular emphasis on type I (hypokalemic distal RTA) and type II (proximal) RTA while reviewing their pathogenesis from a physiological "bottom-up" approach. In addition, the factors involved in the generation of metabolic acidosis in both type I and II RTA are reviewed highlighting the importance of altered renal ammonia production/partitioning and new HCO3- generation. Our understanding of the underlying tubular transport and extrarenal abnormalities has significantly improved since the first recognition of RTA as a clinical entity because of significant advances in clinical acid-base chemistry, whole tubule and single-cell H+/base transport, and the molecular characterization of the various transporters and channels that are functionally affected in patients with RTA. Despite these advances, additional studies are needed to address the underlying mechanisms involved in hypokalemia, altered ammonia production/partitioning, hypercalciuria, nephrocalcinosis, cystic abnormalities, and CKD progression in these patients.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, and Brain Research Institute, UCLA, Los Angeles, CA.
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Ayasse N, de Bruijn PIA, Berg P, Sørensen MV, Leipziger J. Hydrochlorothiazide and acute urinary acidification: The "voltage hypothesis" of ENaC-dependent H + secretion refuted. Acta Physiol (Oxf) 2018; 223:e13013. [PMID: 29226589 DOI: 10.1111/apha.13013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/20/2017] [Accepted: 12/04/2017] [Indexed: 11/26/2022]
Abstract
AIM The "voltage hypothesis" of H+ secretion states that urinary acidification following increased Na+ delivery to the collecting duct (CD) is ENaC dependent leading to transepithelial voltage-dependent increase in H+ secretion. We recently showed that furosemide acidifies the urine independently of ENaC activity. If the voltage hypothesis holds, hydrochlorothiazide (HCT) must acidify the urine. We here tested the acute effect of HCT on urine pH under normal and high ENaC expression. METHODS Mice subjected to a control or a low-Na+ diet were anesthetized and infused (0.5 mL h-1 ) with saline. Catheterization of the urinary bladder allowed real-time measurement of diuresis and urine pH. Mice received either HCT (1 mg mL-1 ) or vehicle. Urinary Na+ and K+ excretions were determined by flame photometry. ENaC expression levels were measured by semi-quantitative Western blotting. RESULTS (1) HCT increased diuresis and natriuresis in both diet groups. (2) K+ excretion rates increased after HCT administration from 18.6 ± 1.3 to 31.7 ± 2.5 μmol h-1 in the control diet group and from 23.0 ± 1.3 to 48.7 ± 3.0 μmol h-1 in the low-Na+ diet group. (3) Mice fed a low-Na+ diet showed a marked upregulation of ENaC. (4) Importantly, no acute changes in urine pH were observed after the administration of HCT in either group. CONCLUSION Acute administration of HCT has no effect on urine pH. Similarly, substantial functional and molecular upregulation of ENaC did not cause HCT to acutely change urine pH. Thus, an increased Na+ load to the CD does not alter urine pH. This supports our previous finding and likely falsifies the voltage hypothesis of H+ secretion.
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Affiliation(s)
- N. Ayasse
- Department of Biomedicine, Physiology and Biophysics; Aarhus University; Aarhus C Denmark
| | - P. I. A. de Bruijn
- Department of Biomedicine, Physiology and Biophysics; Aarhus University; Aarhus C Denmark
| | - P. Berg
- Department of Biomedicine, Physiology and Biophysics; Aarhus University; Aarhus C Denmark
| | - M. V. Sørensen
- Department of Biomedicine, Physiology and Biophysics; Aarhus University; Aarhus C Denmark
- Aarhus Institute of Advanced Studies; Aarhus University; Aarhus C Denmark
| | - J. Leipziger
- Department of Biomedicine, Physiology and Biophysics; Aarhus University; Aarhus C Denmark
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Pathare G, Dhayat NA, Mohebbi N, Wagner CA, Bobulescu IA, Moe OW, Fuster DG. Changes in V-ATPase subunits of human urinary exosomes reflect the renal response to acute acid/alkali loading and the defects in distal renal tubular acidosis. Kidney Int 2018; 93:871-880. [PMID: 29310826 DOI: 10.1016/j.kint.2017.10.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 10/02/2017] [Accepted: 10/05/2017] [Indexed: 12/26/2022]
Abstract
In the kidney, final urinary acidification is achieved by V-ATPases expressed in type A intercalated cells. The B1 subunit of the V-ATPase is required for maximal urinary acidification, while the role of the homologous B2 subunit is less clear. Here we examined the effect of acute acid/alkali loading in humans on B1 and B2 subunit abundance in urinary exosomes in normal individuals and of acid loading in patients with distal renal tubular acidosis (dRTA). Specificities of B1 and B2 subunit antibodies were verified by yeast heterologously expressing human B1 and B2 subunits, and murine wild-type and B1-deleted kidney lysates. Acute ammonium chloride loading elicited systemic acidemia, a drop in urinary pH, and increased urinary ammonium excretion. Nadir urinary pH was achieved at four to five hours, and exosomal B1 abundance was significantly increased at two through six hours after ammonium chloride loading. After acute equimolar sodium bicarbonate loading, blood and urinary pH rose rapidly, with a concomitant reduction of exosomal B1 abundance within two hours, which remained lower throughout the test. In contrast, no change in exosomal B2 abundance was found following acid or alkali loading. In patients with inherited or acquired distal RTA, the urinary B1 subunit was extremely low or undetectable and did not respond to acid loading in urine, whereas no change in B2 subunit was found. Thus, both B1 and B2 subunits of the V-ATPase are detectable in human urinary exosomes, and acid and alkali loading or distal RTA cause changes in the B1 but not B2 subunit abundance in urinary exosomes.
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Affiliation(s)
- Ganesh Pathare
- Division of Nephrology and Hypertension, Bern University Hospital, University of Bern, Bern, Switzerland; Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland; National Centre of Competence in Research Transcure, University of Bern, Bern, Switzerland
| | - Nasser A Dhayat
- Division of Nephrology and Hypertension, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Nilufar Mohebbi
- Division of Nephrology, University Hospital Zurich, Zurich, Switzerland
| | - Carsten A Wagner
- Institute of Physiology, University of Zurich, Zurich, Switzerland; National Center for Competence in Research Kidney.CH, Zurich, Switzerland
| | - Ion A Bobulescu
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Orson W Moe
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA; Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Daniel G Fuster
- Division of Nephrology and Hypertension, Bern University Hospital, University of Bern, Bern, Switzerland; Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland; National Centre of Competence in Research Transcure, University of Bern, Bern, Switzerland.
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Bech AP, Wetzels JFM, Nijenhuis T. Reference values of renal tubular function tests are dependent on age and kidney function. Physiol Rep 2017; 5. [PMID: 29212860 PMCID: PMC5727289 DOI: 10.14814/phy2.13542] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/09/2017] [Accepted: 11/10/2017] [Indexed: 11/24/2022] Open
Abstract
Electrolyte disorders due to tubular disorders are rare, and knowledge about validated clinical diagnostic tools such as tubular function tests is sparse. Reference values for tubular function tests are based on studies with small sample size in young healthy volunteers. Patients with tubular disorders, however, frequently are older and can have a compromised renal function. We therefore evaluated four tubular function tests in individuals with different ages and renal function. We performed furosemide, thiazide, furosemide‐fludrocortisone, and desmopressin tests in healthy individuals aged 18–50 years, healthy individuals aged more than 50 years and individuals with compromised renal function. For each tubular function test we included 10 individuals per group. The responses in young healthy individuals were in line with previously reported values in literature. The maximal increase in fractional chloride excretion after furosemide was below the lower limit of young healthy individuals in 5/10 older subjects and in 2/10 patients with compromised renal function. The maximal increase in fractional chloride excretion after thiazide was below the lower limit of young healthy individuals in 6/10 older subjects and in 7/10 patients with compromised renal function. Median maximal urine osmolality after desmopressin was 1002 mosmol/kg H2O in young healthy individuals, 820 mosmol/kg H2O in older subjects and 624 mosmol/kg H2O in patients with compromised renal function. Reference values for tubular function tests obtained in young healthy adults thus cannot simply be extrapolated to older patients or patients with compromised kidney function. Larger validation studies are needed to define true reference values in these patient categories.
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Affiliation(s)
- Anneke P Bech
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jack F M Wetzels
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Tom Nijenhuis
- Department of Nephrology, Radboud University Medical Center, Nijmegen, The Netherlands
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46
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Pathophysiology, diagnosis and treatment of inherited distal renal tubular acidosis. J Nephrol 2017; 31:511-522. [DOI: 10.1007/s40620-017-0447-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 09/21/2017] [Indexed: 10/18/2022]
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47
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Bech AP, Wetzels JF, Nijenhuis T. Use of the Furosemide Fludrocortisone Test to Clinically Assess Distal Tubular Acidification. Am J Kidney Dis 2017. [DOI: 10.1053/j.ajkd.2017.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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48
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Dhayat NA, Gradwell MW, Pathare G, Anderegg M, Schneider L, Luethi D, Mattmann C, Moe OW, Vogt B, Fuster DG. Furosemide/Fludrocortisone Test and Clinical Parameters to Diagnose Incomplete Distal Renal Tubular Acidosis in Kidney Stone Formers. Clin J Am Soc Nephrol 2017; 12:1507-1517. [PMID: 28775126 PMCID: PMC5586565 DOI: 10.2215/cjn.01320217] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Accepted: 05/12/2017] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Incomplete distal renal tubular acidosis is a well known cause of calcareous nephrolithiasis but the prevalence is unknown, mostly due to lack of accepted diagnostic tests and criteria. The ammonium chloride test is considered as gold standard for the diagnosis of incomplete distal renal tubular acidosis, but the furosemide/fludrocortisone test was recently proposed as an alternative. Because of the lack of rigorous comparative studies, the validity of the furosemide/fludrocortisone test in stone formers remains unknown. In addition, the performance of conventional, nonprovocative parameters in predicting incomplete distal renal tubular acidosis has not been studied. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We conducted a prospective study in an unselected cohort of 170 stone formers that underwent sequential ammonium chloride and furosemide/fludrocortisone testing. RESULTS Using the ammonium chloride test as gold standard, the prevalence of incomplete distal renal tubular acidosis was 8%. Sensitivity and specificity of the furosemide/fludrocortisone test were 77% and 85%, respectively, yielding a positive predictive value of 30% and a negative predictive value of 98%. Testing of several nonprovocative clinical parameters in the prediction of incomplete distal renal tubular acidosis revealed fasting morning urinary pH and plasma potassium as the most discriminative parameters. The combination of a fasting morning urinary threshold pH <5.3 with a plasma potassium threshold >3.8 mEq/L yielded a negative predictive value of 98% with a sensitivity of 85% and a specificity of 77% for the diagnosis of incomplete distal renal tubular acidosis. CONCLUSIONS The furosemide/fludrocortisone test can be used for incomplete distal renal tubular acidosis screening in stone formers, but an abnormal furosemide/fludrocortisone test result needs confirmation by ammonium chloride testing. Our data furthermore indicate that incomplete distal renal tubular acidosis can reliably be excluded in stone formers by use of nonprovocative clinical parameters.
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Affiliation(s)
- Nasser A. Dhayat
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
| | - Michael W. Gradwell
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
| | - Ganesh Pathare
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
- Swiss National Centre of Competence in Research TransCure, University of Bern, Bern, Switzerland
| | - Manuel Anderegg
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
- Swiss National Centre of Competence in Research TransCure, University of Bern, Bern, Switzerland
| | - Lisa Schneider
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
| | - David Luethi
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
| | - Cedric Mattmann
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
| | - Orson W. Moe
- Departments of Internal Medicine and Physiology, and the Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, Texas; and
| | - Bruno Vogt
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
| | - Daniel G. Fuster
- Division of Nephrology and Hypertension, Bern University Hospital, Bern, Switzerland
- Swiss National Centre of Competence in Research TransCure, University of Bern, Bern, Switzerland
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Goldfarb DS. Refining Diagnostic Approaches in Nephrolithiasis: Incomplete Distal Renal Tubular Acidosis. Clin J Am Soc Nephrol 2017; 12:1380-1382. [PMID: 28775128 PMCID: PMC5586576 DOI: 10.2215/cjn.07160717] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- David S Goldfarb
- Nephrology Division, New York Harbor Department of Veterans Affairs Medical Center, New York, New York; and Nephrology Division, New York University School of Medicine, New York, New York
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Berend K. Review of the Diagnostic Evaluation of Normal Anion Gap Metabolic Acidosis. KIDNEY DISEASES 2017; 3:149-159. [PMID: 29344509 DOI: 10.1159/000479279] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Revised: 05/29/2017] [Indexed: 12/29/2022]
Abstract
Background Normal anion gap metabolic acidosis is a common but often misdiagnosed clinical condition associated with diarrhea and renal tubular acidosis (RTA). Early identification of RTA remains challenging for inexperienced physicians, and diagnosis and treatment are often delayed. Summary The presence of RTA should be considered in any patient with a high chloride level when the CL-/Na+ ratio is above 0.79, if the patient does not have diarrhea. In patients with significant hyperkalemia one should evaluate for RTA type 4, especially in diabetic patients, with a relatively conserved renal function. A still growing list of medications can produce RTA. Key Messages This review highlights practical aspects concerning normal anion gap metabolic acidosis.
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