1
|
Kunchur MG, Mauch TJ, Parkanzky M, Rahilly LJ. A review of renal tubular acidosis. J Vet Emerg Crit Care (San Antonio) 2024. [PMID: 39023331 DOI: 10.1111/vec.13407] [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: 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.
Collapse
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
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Gómez-Conde S, García-Castaño A, Aguirre M, Herrero M, Gondra L, García-Pérez N, García-Ledesma P, Martín-Penagos L, Dall'Anese C, Ariceta G, Castaño L, Madariaga L. Molecular aspects and long-term outcome of patients with primary distal renal tubular acidosis. Pediatr Nephrol 2021; 36:3133-3142. [PMID: 33881640 DOI: 10.1007/s00467-021-05066-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 03/17/2021] [Accepted: 03/23/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND Primary distal renal tubular acidosis (dRTA) is a rare genetic disorder caused by impaired distal mechanisms of urinary acidification. Most cases are secondary to pathogenic variants in ATP6V0A4, ATP6V1B1, and SLC4A1 genes, which encode transporters regulating acid-base balance in the collecting duct. METHODS Retrospective study of molecular and clinical data from diagnosis and long-term follow-up (10, 20, and 40±10 years) of 16 patients with primary dRTA diagnosed in childhood. RESULTS Molecular analyses revealed nine patients had ATP6V0A4 pathogenic variants, five in ATP6V1B1, and two in SLC4A1. A novel intragenic deletion and a common ATP6V0A4 gene variant (c.1691 + 2dupT) in ATP6V0A4 occurred in two-thirds of these patients, suggesting a founder effect. Median age at diagnosis was 3.25 months (IQR 1, 13.5), which was higher in the SLC4A1 group. Median SDS height at diagnosis was -1.02 (IQR -1.79, 0.14). Delayed clinical diagnosis was significantly related to growth failure (P = 0.01). Median SDS height at 20 years follow-up was -1.23 (IQR -1.71, -0.48), and did not significantly improve from diagnosis (P = 0.76). Kidney function declined over time: at last follow-up, 43% had moderate to severe chronic kidney disease (CKD). Adequate metabolic control was not related to CKD development. Incidence of sensorineural hearing loss (SNHL) was high in ATP6V1B1 patients, though not universal. Patients harboring ATP6V0A4 variants also developed SNHL at a high rate (80%) over time. CONCLUSIONS Patients with dRTA can develop moderate to severe CKD over time with a high frequency despite adequate metabolic control. Early diagnosis ameliorates long-term height prognosis.
Collapse
Affiliation(s)
| | - Alejandro García-Castaño
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain
| | - Mireia Aguirre
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Pediatric Nephrology Department, Cruces University Hospital, Barakaldo, Spain
| | - María Herrero
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Pediatric Nephrology Department, Cruces University Hospital, Barakaldo, Spain
| | - Leire Gondra
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Pediatric Nephrology Department, Cruces University Hospital, Barakaldo, Spain.,Pediatric Department, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Nélida García-Pérez
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,Pediatric Department, University of the Basque Country UPV/EHU, Leioa, Spain.,Pediatric Nephrology Department, Basurto University Hospital, Bilbao, Spain
| | | | - Luis Martín-Penagos
- Nephrology Department, Marqués de Valdecilla University Hospital, Santander, Spain
| | | | - Gema Ariceta
- Pediatric Nephrology Department, Vall d'Hebron University Hospital, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Luis Castaño
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain.,CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain.,Pediatric Department, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Leire Madariaga
- Biocruces Bizkaia Health Research Institute, Barakaldo, Spain. .,CIBERDEM, CIBERER, Endo-ERN, Madrid, Spain. .,Pediatric Nephrology Department, Cruces University Hospital, Barakaldo, Spain. .,Pediatric Department, University of the Basque Country UPV/EHU, Leioa, Spain.
| |
Collapse
|
4
|
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: 9] [Impact Index Per Article: 3.0] [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.
Collapse
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
| |
Collapse
|
5
|
Dawman L, Tiewsoh K, Barman P, Pratyusha K, Chaakchhuak L, Sharawat IK. Phenotype and Genotype Profile of Children with Primary Distal Renal Tubular Acidosis: A 10-Year Experience from a North Indian Teaching Institute. J Pediatr Genet 2021; 11:221-226. [DOI: 10.1055/s-0041-1724114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 01/13/2021] [Indexed: 10/22/2022]
Abstract
AbstractPrimary distal renal tubular acidosis (dRTA) or Type 1 RTA in children is caused by a genetic defect (involved genes ATP6V0A4, ATP6V1B1, SLC4A1, FOXI1, or WDR72), which causes tubular transport defects characterized by an inability to appropriately acidify urine with resultant persistent hyperchloremic metabolic acidosis. Retrospective analysis of 28 children (14 males) under the age of 14 years with dRTA seen from 2010 to 2019 was reviewed, and detailed clinic records were analyzed. The clinical features, investigations, and response to treatment were recorded. The median age of the children at presentation was 30 months (range: 9.25–72 months), and the median age at onset of symptoms was 2 months. All the children had growth failure, polyuria, and polydipsia at presentation. Mean serum potassium, pH, bicarbonate, and anion gap at presentation was 2.3 ± 0.5 mmol/L, 7.22 ± 0.09, 13.28 ± 4.37 mmol/L, and 9.3 ± 2.18, respectively. Mean serum potassium, pH, bicarbonate at follow-up was 3.88 ± 0.6 mmol/L, 7.35 ± 0.06, and 20.13 ± 4.17 mmol/L, respectively. The median z-score for the weight for age and height for age at initial presentation was −4.77 (–7.68 to –3.74) and –4.21 (–5.42 to –2.37) and at follow-up was –3.35 (–5.29 to –1.55) and –3.84 (–5.36 to –1.63), respectively. Twenty-two (78.6%) children had medullary nephrocalcinosis. Four children had sensorineural hearing loss. Seven children had genetic testing done, and six had pathogenic or likely pathogenic variants in ATP6V1B1 and ATP6V0A4 gene. Children with dRTA have a guarded prognosis and ATP6V1B1 and ATP6V0A4 mutations are the most common implicated genetic defect in Indian children with distal RTA.
Collapse
Affiliation(s)
- Lesa Dawman
- Department of Pediatrics, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Karalanglin Tiewsoh
- Department of Pediatrics, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Prabal Barman
- Department of Pediatrics, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Kambagiri Pratyusha
- Department of Pediatrics, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Lalawmpuia Chaakchhuak
- Department of Pediatrics, Advanced Pediatrics Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India
| | - Indar Kumar Sharawat
- Department of Pediatrics, All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India
| |
Collapse
|
6
|
Boro H, Goyal A, Naik SS, Tandon N. Primary Sjögren's syndrome manifesting as sclerotic metabolic bone disease. BMJ Case Rep 2021; 14:14/1/e237987. [PMID: 33431459 PMCID: PMC7802734 DOI: 10.1136/bcr-2020-237987] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Primary Sjögren's syndrome (pSS) is a chronic slowly progressive autoimmune disease characterised by lymphocytic infiltration of salivary and lacrimal glands with varying degree of systemic involvement. Renal involvement, a recognised extraglandular manifestation of pSS, is commonly related to tubular dysfunction and generally manifests as distal renal tubular acidosis (RTA), proximal RTA, tubular proteinuria and nephrogenic diabetes insipidus. Untreated long-standing RTA is known to cause metabolic bone disease. Here, we present the report of a patient with sclerotic metabolic bone disease related to pSS with combined distal and proximal RTA and negative workup for other causes of sclerotic bone disease. A significant clinical and biochemical improvement, including recovery of proximal tubular dysfunction, was noted with alkali therapy. This case suggests the need to consider pSS in the diagnostic algorithm of a patient presenting with sclerotic bone disease.
Collapse
Affiliation(s)
- Hiya Boro
- Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, Delhi, India
| | - Alpesh Goyal
- Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, Delhi, India
| | | | - Nikhil Tandon
- Endocrinology and Metabolism, All India Institute of Medical Sciences, New Delhi, Delhi, India
| |
Collapse
|
7
|
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]
|
8
|
Hanna RM, Ahdoot RS, Kalantar-Zadeh K, Ghobry L, Kurtz I. Calcium Transport in the Kidney and Disease Processes. Front Endocrinol (Lausanne) 2021; 12:762130. [PMID: 35299844 PMCID: PMC8922474 DOI: 10.3389/fendo.2021.762130] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 11/25/2021] [Indexed: 11/25/2022] Open
Abstract
Calcium is a key ion involved in cardiac and skeletal muscle contractility, nerve function, and skeletal structure. Global calcium balance is affected by parathyroid hormone and vitamin D, and calcium is shuttled between the extracellular space and the bone matrix compartment dynamically. The kidney plays an important role in whole-body calcium balance. Abnormalities in the kidney transport proteins alter the renal excretion of calcium. Various hormonal and regulatory pathways have evolved that regulate the renal handling of calcium to maintain the serum calcium within defined limits despite dynamic changes in dietary calcium intake. Dysregulation of renal calcium transport can occur pharmacologically, hormonally, and via genetic mutations in key proteins in various nephron segments resulting in several disease processes. This review focuses on the regulation transport of calcium in the nephron. Genetic diseases affecting the renal handling of calcium that can potentially lead to changes in the serum calcium concentration are reviewed.
Collapse
Affiliation(s)
- Ramy M. Hanna
- Division of Nephrology, Department of Medicine, University of California Irvine (UCI) School of Medicine, Orange, CA, United States
- *Correspondence: Ramy M. Hanna,
| | - Rebecca S. Ahdoot
- Division of Nephrology, Department of Medicine, University of California Irvine (UCI) School of Medicine, Orange, CA, United States
| | - Kamyar Kalantar-Zadeh
- Division of Nephrology, Department of Medicine, University of California Irvine (UCI) School of Medicine, Orange, CA, United States
| | - Lena Ghobry
- School of Public Health, University of Pittsburgh, Pittsburgh, PA, United States
| | - Ira Kurtz
- Division of Nephrology, Department of Medicine, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, CA, United States
- University of California Los Angeles (UCLA) Brain Research Center, Los Angeles, CA, United States
| |
Collapse
|
9
|
Agrawal SS, Mishra CK, Agrawal C, Chakraborty PP. Rickets with hypophosphatemia, hypokalemia and normal anion gap metabolic acidosis: not always an easy diagnosis. BMJ Case Rep 2020; 13:13/1/e233350. [DOI: 10.1136/bcr-2019-233350] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Rickets other than those associated with advanced kidney disease, isolated distal renal tubular acidosis (dRTA) and hypophosphatasia (defective tissue non-specific alkaline phosphatase) are associated with hypophosphatemia due to abnormal proximal tubular reabsorption of phosphate. dRTA, however, at times is associated with completely reversible proximal tubular dysfunction. On the other hand, severe hypophosphatemia of different aetiologies may also interfere with both distal tubular acid excretion and proximal tubular functions giving rise to transient secondary renal tubular acidosis (distal and/or proximal). Hypophosphatemia and non-anion gap metabolic acidosis thus pose a diagnostic challenge occasionally. A definitive diagnosis and an appropriate management of the primary defect results in complete reversal of the secondary abnormality. A child with vitamin D resistant rickets was thoroughly evaluated and found to have primary dRTA with secondary proximal tubular dysfunction in the form of phosphaturia and low molecular weight proteinuria. The child was treated only with oral potassium citrate. A complete clinical, biochemical and radiological improvement was noticed in follow-up.
Collapse
|
10
|
Watanabe T. Improving outcomes for patients with distal renal tubular acidosis: recent advances and challenges ahead. PEDIATRIC HEALTH MEDICINE AND THERAPEUTICS 2018; 9:181-190. [PMID: 30588151 PMCID: PMC6296208 DOI: 10.2147/phmt.s174459] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Primary distal renal tubular acidosis (dRTA) is a rare genetic disorder caused by impaired distal acidification due to a failure of type A intercalated cells (A-ICs) in the collecting tubule. dRTA is characterized by persistent hyperchloremia, a normal plasma anion gap, and the inability to maximally lower urinary pH in the presence of systemic metabolic acidosis. Common clinical features of dRTA include vomiting, failure to thrive, polyuria, hypercalciuria, hypocitraturia, nephrocalcinosis, nephrolithiasis, growth delay, and rickets. Mutations in genes encoding three distinct transport proteins in A-ICs have been identified as causes of dRTA, including the B1/ATP6V1B1 and a4/ATP6V0A4 subunits of the vacuolar-type H+-ATPase (H+-ATPase) and the chloride–bicarbonate exchanger AE1/SLC4A1. Homozygous or compound heterozygous mutations in ATP6V1B1 and ATP6V0A4 lead to autosomal recessive (AR) dRTA. dRTA caused by SLC4A1 mutations can occur with either autosomal dominant or AR transmission. Red blood cell abnormalities have been associated with AR dRTA due to SLC4A1 mutations, including hereditary spherocytosis, Southeast Asia ovalocytosis, and others. Some patients with dRTA exhibit atypical clinical features, including transient and reversible proximal tubular dysfunction and hyperammonemia. Incomplete dRTA presents with inadequate urinary acidification, but without spontaneous metabolic acidosis and recurrent urinary stones. Heterozygous mutations in the AE1 or H+-ATPase genes have recently been reported in patients with incomplete dRTA. Early and sufficient doses of alkali treatment are needed for patients with dRTA. Normalized serum bicarbonate, urinary calcium excretion, urinary low-molecular-weight protein levels, and growth rate are good markers of adherence to and/or efficacy of treatment. The prognosis of dRTA is generally good in patients with appropriate treatment. However, recent studies showed an increased frequency of chronic kidney disease (CKD) in patients with dRTA during long-term follow-up. The precise pathogenic mechanisms of CKD in patients with dRTA are unknown.
Collapse
Affiliation(s)
- Toru Watanabe
- Department of Pediatrics, Niigata City General Hospital, Niigata City 950-1197, Japan,
| |
Collapse
|
11
|
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.
Collapse
|
12
|
Batlle D, Arruda J. Hyperkalemic Forms of Renal Tubular Acidosis: Clinical and Pathophysiological Aspects. Adv Chronic Kidney Dis 2018; 25:321-333. [PMID: 30139459 DOI: 10.1053/j.ackd.2018.05.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In contrast to distal type I or classic renal tubular acidosis (RTA) that is associated with hypokalemia, hyperkalemic forms of RTA also occur usually in the setting of mild-to-moderate CKD. Two pathogenic types of hyperkalemic metabolic acidosis are frequently encountered in adults with underlying CKD. One type, which corresponds to some extent to the animal model of selective aldosterone deficiency (SAD) created experimentally by adrenalectomy and glucocorticoid replacement, is manifested in humans by low plasma and urinary aldosterone levels, reduced ammonium excretion, and preserved ability to lower urine pH below 5.5. This type of hyperkalemic RTA is also referred to as type IV RTA. It should be noted that the mere deficiency of aldosterone when glomerular filtration rate is completely normal only causes a modest decline in plasma bicarbonate which emphasizes the importance of reduced glomerular filtration rate in the development of the hyperchloremic metabolic acidosis associated with SAD. Another type of hyperkalemic RTA distinctive from SAD in which plasma aldosterone is not reduced is referred to as hyperkalemic distal renal tubular acidosis because urine pH cannot be reduced despite acidemia or after provocative tests aimed at increasing sodium-dependent distal acidification such as the administration of sodium sulfate or loop diuretics with or without concurrent mineralocorticoid administration. This type of hyperkalemic RTA (also referred to as voltage-dependent distal renal tubular acidosis) has been best described in patients with obstructive uropathy and resembles the impairment in both hydrogen ion and potassium secretion that are induced experimentally by urinary tract obstruction and when sodium transport in the cortical collecting tubule is blocked by amiloride.
Collapse
|
13
|
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.
Collapse
Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, and Brain Research Institute, UCLA, Los Angeles, CA.
| |
Collapse
|
14
|
Park E, Cho M, Hyun H, Shin J, Lee J, Park Y, Choi H, Kang H, Cheong H. Genotype–Phenotype Analysis in Pediatric Patients with Distal Renal Tubular Acidosis. Kidney Blood Press Res 2018; 43:513-521. [DOI: 10.1159/000488698] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/23/2018] [Indexed: 11/19/2022] Open
|
15
|
Liew YP, Rogers TA, Garb JL, Allen HF, Reiter EO, Campfield TJ, Dharnidharka VR, Braden GL. Type 3 renal tubular acidosis associated with growth hormone deficiency. J Pediatr Endocrinol Metab 2017; 30:1047-1053. [PMID: 28888090 DOI: 10.1515/jpem-2016-0460] [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: 12/09/2016] [Accepted: 07/24/2017] [Indexed: 11/15/2022]
Abstract
BACKGROUND We identified two boys with type 3 renal tubular acidosis (RTA) and growth hormone deficiency and we sought to differentiate them from children with classic type 1 distal RTA. METHODS We reviewed all children <6 years of age with RTA referred over a 13-year period and compared the growth response to alkali therapy in these two boys and in 28 children with only type 1 distal RTA. RESULTS All children with type 1 RTA reached the 5th percentile or higher on CDC growth charts within 2 years of alkali therapy. Their mean height standard deviation score (SDS) improved from -1.4 to -0.6 SDS and their mean mid-parental height (MPH) SDS improved from -0.6 to 0 SDS after 2 years. In contrast, the boys with growth hormone deficiency had a height SDS of -1.4 and -2.4 SDS after 2 years of alkali and the MPH SDS were both -2.6 SDS after 2 years of alkali therapy. Growth hormone therapy accelerated their growth to normal levels and led to long-term correction of RTA. CONCLUSIONS A child with type 1 RTA whose height response after 2 years of alkali therapy is inadequate should undergo provocative growth hormone testing.
Collapse
|
16
|
Besouw MTP, Bienias M, Walsh P, Kleta R, Van't Hoff WG, Ashton E, Jenkins L, Bockenhauer D. Clinical and molecular aspects of distal renal tubular acidosis in children. Pediatr Nephrol 2017; 32:987-996. [PMID: 28188436 DOI: 10.1007/s00467-016-3573-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 12/16/2016] [Accepted: 12/19/2016] [Indexed: 11/30/2022]
Abstract
BACKGROUND Distal renal tubular acidosis (dRTA) is characterized by hyperchloraemic metabolic acidosis, hypokalaemia, hypercalciuria and nephrocalcinosis. It is due to reduced urinary acidification by the α-intercalated cells in the collecting duct and can be caused by mutations in genes that encode subunits of the vacuolar H+-ATPase (ATP6V1B1, ATP6V0A4) or the anion exchanger 1 (SLC4A1). Treatment with alkali is the mainstay of therapy. METHODS This study is an analysis of clinical data from a long-term follow-up of 24 children with dRTA in a single centre, including a genetic analysis. RESULTS Of the 24 children included in the study, genetic diagnosis was confirmed in 19 patients, with six children having mutations in ATP6V1B1, ten in ATP6V0A4 and three in SLC4A1; molecular diagnosis was not available for five children. Five novel mutations were detected (2 in ATP6V1B1 and 3 in ATP6V0A4). Two-thirds of patients presented with features of proximal tubular dysfunction leading to an erroneous diagnosis of renal Fanconi syndrome. The proximal tubulopathy disappeared after resolution of acidosis, indicating the importance of following proximal tubular function to establish the correct diagnosis. Growth retardation with a height below -2 standard deviation score was found in ten patients at presentation, but persisted in only three of these children once established on alkali treatment. Sensorineural hearing loss was found in five of the six patients with an ATP6V1B1 mutation. Only one patient with an ATP6V0A4 mutation had sensorineural hearing loss during childhood. Nine children developed medullary cysts, but without apparent clinical consequences. Cyst development in this cohort was not correlated with age at therapy onset, molecular diagnosis, growth parameters or renal function. CONCLUSION In general, the prognosis of dRTA is good in children treated with alkali.
Collapse
Affiliation(s)
- Martine T P Besouw
- Department of Pediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, WC1N 3JH, UK
| | - Marc Bienias
- Department of Pediatrics, Medical Faculty Carl Gustav Carus, Technical University Dresden, Dresden, Germany
| | - Patrick Walsh
- Great North Children's Hospital, Newcastle upon Tyne NHS Foundation Trust, Newcastle, UK
| | - Robert Kleta
- Department of Pediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, WC1N 3JH, UK.,Centre for Nephrology, University College London Institute of Child Health, London, UK
| | - William G Van't Hoff
- Department of Pediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, WC1N 3JH, UK
| | - Emma Ashton
- North East Thames Regional Genetics Service Laboratories, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Lucy Jenkins
- North East Thames Regional Genetics Service Laboratories, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Detlef Bockenhauer
- Department of Pediatric Nephrology, Great Ormond Street Hospital for Children NHS Foundation Trust, Great Ormond Street, London, WC1N 3JH, UK. .,Centre for Nephrology, University College London Institute of Child Health, London, UK.
| |
Collapse
|
17
|
Gil-Peña H, Mejía N, Santos F. Renal tubular acidosis. J Pediatr 2014; 164:691-698.e1. [PMID: 24345454 DOI: 10.1016/j.jpeds.2013.10.085] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 09/10/2013] [Accepted: 10/30/2013] [Indexed: 11/12/2022]
Affiliation(s)
- Helena Gil-Peña
- Division of Pediatric Nephrology, Hospital Universitario Central de Asturias, Oviedo, Spain; Department of Medicine, University of Oviedo, Oviedo, Spain
| | - Natalia Mejía
- Department of Pediatrics, University of Los Andes, Bogotá, Colombia
| | - Fernando Santos
- Division of Pediatric Nephrology, Hospital Universitario Central de Asturias, Oviedo, Spain; Department of Medicine, University of Oviedo, Oviedo, Spain.
| |
Collapse
|
18
|
Renal Tubular Acidosis and Stone Formation. Urolithiasis 2012. [DOI: 10.1007/978-1-4471-4387-1_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
19
|
Bockenhauer D, van't Hoff W, Dattani M, Lehnhardt A, Subtirelu M, Hildebrandt F, Bichet DG. Secondary nephrogenic diabetes insipidus as a complication of inherited renal diseases. Nephron Clin Pract 2010; 116:p23-9. [PMID: 20733335 DOI: 10.1159/000320117] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Accepted: 06/10/2010] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND/AIMS Nephrogenic diabetes insipidus (NDI) is a serious condition with large water losses in the urine and the risk of hypernatremic dehydration. Unrecognized, repeated episodes of hypernatremic dehydration can lead to permanent brain damage. Primary NDI is due to mutations in either AVPR2 or AQP2. NDI can also occur as a secondary complication, most commonly from obstructive uropathy or chronic lithium therapy. We observed NDI in patients with inherited tubulopathies and aimed to define the clinical and molecular phenotype. METHODS We reviewed the medical notes of 4 patients with clinical NDI and an underlying molecularly confirmed diagnosis of nephropathic cystinosis, Bartter syndrome, nephronophthisis and apparent mineralocorticoid excess, respectively. RESULTS The patients all failed to concentrate their urine after administration of 1-desamino[8-D-arginine] vasopressin. None had an identifiable mutation in AVPR2 or AQP2, consistent with secondary NDI. Patients experienced repeated episodes of hypernatremic dehydration, and in 2 cases, NDI was initially thought to be the primary diagnosis, delaying recognition of the underlying problem. CONCLUSION The recognition of this potential complication is important as it has direct implications for clinical management. The occurrence of NDI in association with these conditions provides clues for the etiology of aquaporin deficiency.
Collapse
Affiliation(s)
- D Bockenhauer
- Great Ormond Street Hospital for Children, London, UK.
| | | | | | | | | | | | | |
Collapse
|
20
|
The role of metabolic acidosis in chronic kidney diseases. ASIAN BIOMED 2010. [DOI: 10.2478/abm-2010-0045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Background and objectives: This review focuses on three areas, basic acid-base physiology especially concerning hydrogen ion balance, development of acidosis in chronic kidney disease (CKD), and the consequences of acidosis. We highlight what is well established, what is less certain, and what is unknown. Method and results: The literature on acidosis in CKD were searched from 2004 to 2010 utilizing PubMed, Google Scholar, and Ovid to augment the classic work on acid base physiology over the past three decades. The original research in endogenous acid production and net acid excretion were reviewed. Touching upon the development of metabolic acidosis in CKD, we focused on the consequences of chronic metabolic acidosis on growth and other important variables. Finally, we recognize the significant issue of patients’ medical non-compliance and presented treatment strategy to counter this problem. Conclusion: The correction of acidosis in chronic kidney disease needs no advocacy. The case is made conclusively. Patient non-compliance because of the medication that needs to be taken several times a day is a problem, requiring due diligence.
Collapse
|
21
|
Longitudinal growth in chronic hypokalemic disorders. Pediatr Nephrol 2010; 25:733-7. [PMID: 19902272 DOI: 10.1007/s00467-009-1330-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 09/18/2009] [Accepted: 09/21/2009] [Indexed: 10/20/2022]
Abstract
Growth retardation remains a major complication in children with primary tubular disorders, despite adequate supplemental treatment with electrolytes, water and bicarbonate. Chronic hypokalemia, characteristic of some tubulopathies, impairs growth by mechanisms that are not well known. Association with growth hormone deficiency has been reported in patients with Bartter's or Gitelman's syndrome. Tissue-specific alterations of growth hormone and insulin-like growth factor I axis have been described in experimental models of potassium depletion. Hypokalemic rats gain less body length and weight than pair-fed normokalemic animals and, by contrast, develop renal hypertrophy. These rats have low circulating concentrations of insulin-like growth factor I, depressed messenger ribonucleic acid (mRNA) levels of this peptide in the tibial growth plate, and they are resistant to the longitudinal growth-promoting effects of exogenous growth hormone. The reason for this resistance remains to be defined. No alterations in the intracellular signaling for growth hormone have been found in the liver of hypokalemic rats. However, treatment with high doses of growth hormone is unable to normalize hypertrophy of the epiphyseal cartilage chondrocytes, which are severely disturbed in potassium depletion and likely play an important role in the pathogenia of growth impairment in this condition.
Collapse
|
22
|
Nowik M, Lecca MR, Velic A, Rehrauer H, Brändli AW, Wagner CA. Genome-wide gene expression profiling reveals renal genes regulated during metabolic acidosis. Physiol Genomics 2007; 32:322-34. [PMID: 18056784 DOI: 10.1152/physiolgenomics.00160.2007] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Production and excretion of acids are balanced to maintain systemic acid-base homeostasis. During metabolic acidosis (MA) excess acid accumulates and is removed from the body, a process achieved, at least in part, by increasing renal acid excretion. This acid-secretory process requires the concerted regulation of metabolic and transport pathways, which are only partially understood. Chronic MA causes also morphological remodeling of the kidney. Therefore, we characterized transcriptional changes in mammalian kidney during MA to gain insights into adaptive pathways. Total kidney RNA from control and 2- and 7-days NH(4)Cl treated mice was subjected to microarray gene profiling. We identified 4,075 transcripts significantly (P < 0.05) regulated after 2 and/or 7 days of treatment. Microarray results were confirmed by qRT-PCR. Analysis of candidate genes revealed that a large group of regulated transcripts was represented by different solute carrier transporters, genes involved in cell growth, proliferation, apoptosis, water homeostasis, and ammoniagenesis. Pathway analysis revealed that oxidative phosphorylation was the most affected pathway. Interestingly, the majority of acutely regulated genes after 2 days, returned to normal values after 7 days suggesting that adaptation had occurred. Besides these temporal changes, we detected also differential regulation of selected genes (SNAT3, PEPCK, PDG) between early and late proximal tubule. In conclusion, the mammalian kidney responds to MA by temporally and spatially altering the expression of a large number of genes. Our analysis suggests that many of these genes may participate in various processes leading to adaptation and restoration of normal systemic acid-base and electrolyte homeostasis.
Collapse
Affiliation(s)
- Marta Nowik
- Institute of Physiology and Zurich Center for Human Integrative Physiology (ZIHP), University of Zurich
| | | | | | | | | | | |
Collapse
|
23
|
Gil H, Santos F, García E, Alvarez MV, Ordóñez FA, Málaga S, Coto E. Distal RTA with nerve deafness: clinical spectrum and mutational analysis in five children. Pediatr Nephrol 2007; 22:825-8. [PMID: 17216496 DOI: 10.1007/s00467-006-0417-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 11/22/2006] [Accepted: 12/08/2006] [Indexed: 10/23/2022]
Abstract
Distal renal tubular acidosis (RTA) with nerve deafness is caused by mutations in the ATP6V1B1 gene causing defective function of the H+ -ATPase proton pump. We report five acidotic children (four males) from four unrelated families: blood pH 7.21-7.33, serum bicarbonate 10.8-14.7 mEq/l, minimum urinary pH 6.5-7.1 and fractional excretion of bicarbonate in the presence of normal bicarbonatemia 1.1-5.7%. Growth retardation and nephrocalcinosis, but not hypercalciuria, were common presenting manifestations. Hearing was normally preserved in one of the patients whose sister was severely deaf. One child was homozygous for a known mutation in exon 1: C>T (R31X). Three children were homozygous for a splicing mutation, intron 6 + 1G>A. The other patient was a compound heterozygote, having this mutation and a previously unreported mutation in exon 10: G>A (E330K). Our report shows that hearing loss is not always present in the syndrome of distal renal tubular acidosis with nerve deafness and the absence of hypercalciuria at diagnosis and describes a new mutation responsible for the disease in the ATP6V1B1 gene.
Collapse
Affiliation(s)
- Helena Gil
- Hospital Universitario Central de Asturias, Asturias, Spain
| | | | | | | | | | | | | |
Collapse
|
24
|
Stehberger PA, Shmukler BE, Stuart-Tilley AK, Peters LL, Alper SL, Wagner CA. Distal renal tubular acidosis in mice lacking the AE1 (band3) Cl-/HCO3- exchanger (slc4a1). J Am Soc Nephrol 2007; 18:1408-18. [PMID: 17409310 DOI: 10.1681/asn.2006101072] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Mutations in the human gene that encodes the AE1 Cl(-)/HCO(3)(-) exchanger (SLC4A1) cause autosomal recessive and dominant forms of distal renal tubular acidosis (dRTA). A mouse model that lacks AE1/slc4a1 (slc4a1-/-) exhibited dRTA characterized by spontaneous hyperchloremic metabolic acidosis with low net acid excretion and, inappropriately, alkaline urine without bicarbonaturia. Basolateral Cl(-)/HCO(3)(-) exchange activity in acid-secretory intercalated cells of isolated superfused slc4a1-/- medullary collecting duct was reduced, but alternate bicarbonate transport pathways were upregulated. Homozygous mice had nephrocalcinosis associated with hypercalciuria, hyperphosphaturia, and hypocitraturia. A severe urinary concentration defect in slc4a1-/- mice was accompanied by dysregulated expression and localization of the aquaporin-2 water channel. Mice that were heterozygous for the AE1-deficient allele had no apparent defect. Thus, the slc4a1-/- mouse is the first genetic model of complete dRTA and demonstrates that the AE1/slc4a1 Cl(-)/HCO(3)(-) exchanger is required for maintenance of normal acid-base homeostasis by distal renal regeneration of bicarbonate in the mouse as well as in humans.
Collapse
Affiliation(s)
- Paul A Stehberger
- Institute of Physiology and Zurich Center for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | | | | | | | | | | |
Collapse
|
25
|
|
26
|
Affiliation(s)
- R Curtis Morris
- Department of Medicine, University of California, San Francisco, California 94143-0126, USA.
| | | |
Collapse
|
27
|
Zargar AH, Laway BA, Masoodi SR, Wani AI, Salahuddin M. An aetiological profile of short stature in the Indian subcontinent. J Paediatr Child Health 1998; 34:571-6. [PMID: 9928653 DOI: 10.1046/j.1440-1754.1998.00308.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine the aetiological causes of short stature in a developing region of the world. METHODOLOGY A retrospective analysis was made of data from 193 subjects who were primarily evaluated for short stature in the Endocrinology Department, Institute of Medical Sciences, Kashmir, India. These subjects had a height of more than 3 standard deviations (SD) below the mean for their age and sex, and were seen over a decade (January 1987 to December 1996). A logical and comprehensive clinical and investigative protocol was followed to identify the aetiology of short stature. RESULTS Growth hormone deficiency was the commonest identifiable cause of short stature and accounted for 22.8% of cases. Thirty-six subjects (18.7%) had a normal variant short stature. Renal tubular acidosis was diagnosed in 10.4%, primary hypothyroidism, malnutrition and hypothalamic syndrome in 7.8% each, and growth hormone insensitivity syndrome in 4.1% cases. CONCLUSIONS We conclude that, in addition to growth hormone deficiency and normal variant short stature, distal renal tubular acidosis and growth hormone insensitivity syndrome are significant causes of short stature in India.
Collapse
Affiliation(s)
- A H Zargar
- Department of Endocrinology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Kashmir, India
| | | | | | | | | |
Collapse
|
28
|
Abstract
Two siblings (a boy and a girl) had congenital renal tubular acidosis (RTA) with nephrocalcinosis. Hearing loss due to nerve deafness was diagnosed at 13 1/2 and 9 years of age, respectively. The parents, who are second cousins, are healthy. They have another boy who is unaffected. This is in accordance with an autosomal recessive gene. The association of RTA and deafness was first noted by Royer in 1967, and so far some 50 cases have been described. The literature is reviewed.
Collapse
Affiliation(s)
- C Stoll
- Centre Hospitalo-Universitaire, Strasbourg, France
| | | | | |
Collapse
|
29
|
Challa A, Chan W, Krieg RJ, Thabet MA, Liu F, Hintz RL, Chan JC. Effect of metabolic acidosis on the expression of insulin-like growth factor and growth hormone receptor. Kidney Int 1993; 44:1224-7. [PMID: 8301923 DOI: 10.1038/ki.1993.372] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To further our understanding of the growth failure in metabolic acidosis, we examined the insulin-like growth factor (IGF-I and IGF-II), the IGF binding protein-3 (IGFBP-3), and the hepatic IGF mRNA and growth hormone receptor mRNA in control, pair-fed and acidotic rats. The rats in the last group were made acidotic by using ammonium chloride (1.5%) as their sole fluid intake for eight days. Metabolic acidosis was confirmed by a blood pH of 7.11 +/- 0.10 (mean +/- SD). The mean starting weights for all rats were 167.1 +/- 3.4 grams. Growth impairment was observed in the acidotic rats after one week of ammonium chloride intake. The body weights of the acidotic rats compared to those of the control rats were 155.5 +/- 18.9 g versus 222.8 +/- 9.7 g, P < 0.001; the pair-fed rats weighed 156.8 +/- 19.6 grams. All rats were bled and sacrificed on day 8. Sera and tissue were analyzed with the following results: compared to the ad libitum controls, the same IGF-I concentrations were significantly decreased in the acidotic animals (P < 0.02) as well as pair-fed controls (P < 0.005). The serum IGF-II and IGF-binding protein-3 concentrations were unchanged by acidosis or food restriction. The hepatic IGF-I mRNA was significantly reduced by acidosis (P < 0.01) and pair-feeding (P < 0.01). Compared to control, the mean hepatic IGF mRNA in acidosis was significantly lower (P < 0.01). However, there was no significant difference between the acidotic and the pair-fed groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Collapse
Affiliation(s)
- A Challa
- Departments of Pediatrics and Anatomy, Medical College of Virginia, Richmond
| | | | | | | | | | | | | |
Collapse
|
30
|
Caldas A, Broyer M, Dechaux M, Kleinknecht C. Primary distal tubular acidosis in childhood: clinical study and long-term follow-up of 28 patients. J Pediatr 1992; 121:233-41. [PMID: 1640289 DOI: 10.1016/s0022-3476(05)81194-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The long-term follow-up of 28 patients with congenital primary tubular acidosis is described. Ten patients had affected siblings but no history of similar symptoms in the preceding generation. Deafness was associated in 14 patients and developed before 12 years of age. Deafness was present in all familial cases, and patients without deafness showed no familial incidence, suggesting the existence of two different entities. All patients had growth retardation, which was more severe in the older patients and was always markedly improved by alkaline therapy. Rickets was found in some patients but seemed related to vitamin D deficiency. Catch-up growth was limited to the first 2 years of therapy in patients treated before 2 years of age, but sometimes lasted longer in older patients. Of the 12 patients who reached adulthood, those without rickets achieved a normal height but the others did not. We believe that therapy should be continued throughout life because of the risk of nephrocalcinosis.
Collapse
Affiliation(s)
- A Caldas
- Département de Néphrologie Pédiatrique, Laboratoire d'Explorations Fonctionnelles, Paris, France
| | | | | | | |
Collapse
|
31
|
Rodríguez-Soriano J. Why does renal tubular acidosis cause hypercalciuria? Pediatr Nephrol 1992; 6:144. [PMID: 1571209 DOI: 10.1007/bf00866294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- J Rodríguez-Soriano
- Department of Paediatrics, Basque University School of Medicine, Bilbao, Spain
| |
Collapse
|
32
|
Sly WS, Sato S, Zhu XL. Evaluation of carbonic anhydrase isozymes in disorders involving osteopetrosis and/or renal tubular acidosis. Clin Biochem 1991; 24:311-8. [PMID: 1959222 DOI: 10.1016/0009-9120(91)80005-n] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Carbonic anhydrase II (CA II) deficiency in man is an autosomal recessive disorder manifest by osteopetrosis, renal tubular acidosis, and cerebral calcification. Other features include growth failure and mental retardation. Complications of the osteopetrosis include frequent bone fractures, cranial nerve compression symptoms, and dental malocclusion. The anemia and leukopenia seen in the recessive, lethal infantile form of osteopetrosis are not seen in CA II deficient patients. The renal tubular acidosis usually includes both proximal and distal components. Symptoms of metabolic acidosis respond to therapy, but no specific treatment is available for the osteopetrosis or cerebral calcification. We review here the role of carbonic anhydrases in bone resorption and renal acidification, and discuss clinical features and laboratory findings which distinguish CA II deficiency from other disorders producing osteopetrosis, renal tubular acidosis, or brain calcification. Methods to evaluate patients with pure proximal renal tubular acidosis for deficiency of CA IV are also discussed.
Collapse
Affiliation(s)
- W S Sly
- Edward A. Doisy Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, MO 63104
| | | | | |
Collapse
|
33
|
Santos F, Rey C, Málaga S, Rodríguez LM, Orejas G. The syndrome of renal tubular acidosis and nerve deafness. Discordant manifestations in dizygotic twin brothers. Pediatr Nephrol 1991; 5:235-7. [PMID: 2031843 DOI: 10.1007/bf01095962] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The syndrome of renal tubular acidosis (RTA) and nerve deafness is a distinct nosological entity that is inherited as an autosomal recessive trait. We studied a pair of dizygotic twin brothers both with nerve deafness but only one with RTA. Distal RTA was diagnosed in twin A because of inappropriately high urinary pH (6.9) and low net acid excretion (40.0 muEq/min per 1.73 m2) in the presence of hyperchloraemic metablic acidosis, and fractional bicarbonate excretion of 1.6% at a normal serum bicarbonate concentration. The urine minus blood PCO2 differences (U-B PCO2) during a neutral sodium phosphate load and in alkaline urine induced by bicarbonate supplementation were: 11 and 0 mm Hg, respectively. Twin A developed nephrocalcinosis and, after a 9.5-year follow-up period, was 5.3 cm taller than his brother. Twin B remained asymptomatic. Periodic determinations of blood pH and serum bicarbonate were normal and urine pH decreased to 4.6 in the face of ammonium chloride-induced metabolic acidosis. The U-B PCO2 assessed in alkaline urine was 33.5 mm Hg. Audiograms demonstrated bilateral nerve deafness in both brothers. The presence of deafness without RTA has not been previously reported in this syndrome. This report also shows that a primary distal acidification defect is responsible for the RTA observed in this syndrome.
Collapse
Affiliation(s)
- F Santos
- Department of Paediatrics, Hospital Universitario NS Covadonga, University of Oviedo, Asturias, Spain
| | | | | | | | | |
Collapse
|
34
|
Abstract
Distal renal tubular acidosis (dRTA) is not a single disease. The experimental forms of the syndrome are unsatisfactory as models of the naturally occurring disease, not least because they are seldom complicated by nephrocalcinosis, which is present in the majority of patients with spontaneous disease and contributes to the renal tubular defects found in the syndrome. Impairment of minimal urine pH, reduced urine carbon dioxide tension (PCO2) during passage of alkaline urine, and reduced urinary ammonium (NH4+) excretion, have all been advocated as essential criteria for the diagnosis of dRTA. Minimal urine pH, measured during metabolic acidosis, sulphate infusion, or after oral frusemide, is the yardstick against which other criteria should be assessed. A reduced urinary PCO2 is commonly found in dRTA but is not specific for the syndrome and may be accounted for by tubular defects other than those involving reduced distal hydrogen ion secretion. NH4+ excretion is reduced in most patients with renal acidosis whatever the nature of the underlying renal disease; this function is closely related to nephron mass, and is not specifically impaired in renal tubular disease.
Collapse
Affiliation(s)
- O Wrong
- Department of Medicine, University College and Middlesex School of Medicine, London, UK
| |
Collapse
|
35
|
Abstract
The term renal tubular acidosis (RTA) is applied to a group of transport defects in the reabsorption of bicarbonate (HCO3-), the excretion of hydrogen ions, or both. On clinical and pathophysiological grounds, RTA can be separated into three main types: distal RTA (type 1), proximal RTA (type 2) and hyperkalaemic RTA (type 4). Some patients present combined types of proximal and distal RTA or of hyperkalaemic and distal RTA. Diagnosis of RTA should be suspected when a patient presents a normal plasma anion gap, and hyperchloraemic metabolic acidosis. A normal plasma anion gap (Na(+)-[Cl- + HCO3-] = 8-16 mEq/l) reflects loss of HCO3- from the extracellular fluid via the gastro-intestinal tract or the kidney, dilution of extracellular buffer or administration of hydrochloric acid (HCl) or its precursors. Distinction of RTA from other disorders is greatly facilitated by the study of the urine anion gap (Na+ + K+ - Cl-). This index estimates the urinary concentration of ammonium in a patient with hyperchloraemic metabolic acidosis. A negative urine anion gap (Cl- much greater than Na+ + K+) suggests the presence of gastro-intestinal or renal loss of HCO3-, while a positive urine anion gap (Cl- less than Na+ + K+) is indicative of a distal acidification defect. Determination of plasma potassium, of urine pH at low plasma HCO3- concentration, and of urine PCO2 and fractional excretion of HCO3- at normal plasma HCO3- concentration permits the differentiation between the various types of RTA.
Collapse
|
36
|
Affiliation(s)
- K S Roth
- Department of Pediatrics, Medical College of Virginia, Richmond 23298
| |
Collapse
|
37
|
Kainer G, Chan JC. Renal tubular acidosis: diagnostic work-up treatment and mechanisms of growth retardation. Indian J Pediatr 1988; 55:552-8. [PMID: 3049335 DOI: 10.1007/bf02868438] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
38
|
|
39
|
Abstract
Treatment of a 7-week-old black male who had proximal tubular acidosis with large doses of bicarbonate did not achieve correction of the acidosis and was accompanied by diarrhea. Addition of indomethacin therapy (2 mg/kg/day) was followed by correction of the acidosis and allowed a decrease in the dosage of alkali.
Collapse
|
40
|
|
41
|
Abstract
In the past decade major advances in our understanding of renal tubular hydrogen ion secretion and bicarbonate reabsorption have provided new insight into the pathophysiology of renal tubular acidosis. Thus "fragment to fragment clings" and the number of disorders categorized within the syndrome grows, until we have come to know and name four types, with many subtypes. We hope this new perspective provides a basis for the physician to recognize renal tubular acidosis in its several forms so that an informed decision may be arrived at in choosing the best therapy. The physician may also be prepared to reasonably project the prognosis for each patient. We also hope that our detailed examination of renal acidification will provide a reference for delineation of new clinical expressions of acid-base disorders and kidney malfunction certain to be described in the years ahead.
Collapse
|