1
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Zhang Y, Bock F, Ferdaus M, Arroyo JP, L Rose K, Patel P, Denton JS, Delpire E, Weinstein AM, Zhang MZ, Harris RC, Terker AS. Low potassium activation of proximal mTOR/AKT signaling is mediated by Kir4.2. Nat Commun 2024; 15:5144. [PMID: 38886379 PMCID: PMC11183202 DOI: 10.1038/s41467-024-49562-w] [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: 08/31/2023] [Accepted: 06/07/2024] [Indexed: 06/20/2024] Open
Abstract
The renal epithelium is sensitive to changes in blood potassium (K+). We identify the basolateral K+ channel, Kir4.2, as a mediator of the proximal tubule response to K+ deficiency. Mice lacking Kir4.2 have a compensated baseline phenotype whereby they increase their distal transport burden to maintain homeostasis. Upon dietary K+ depletion, knockout animals decompensate as evidenced by increased urinary K+ excretion and development of a proximal renal tubular acidosis. Potassium wasting is not proximal in origin but is caused by higher ENaC activity and depends upon increased distal sodium delivery. Three-dimensional imaging reveals Kir4.2 knockouts fail to undergo proximal tubule expansion, while the distal convoluted tubule response is exaggerated. AKT signaling mediates the dietary K+ response, which is blunted in Kir4.2 knockouts. Lastly, we demonstrate in isolated tubules that AKT phosphorylation in response to low K+ depends upon mTORC2 activation by secondary changes in Cl- transport. Data support a proximal role for cell Cl- which, as it does along the distal nephron, responds to K+ changes to activate kinase signaling.
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Affiliation(s)
- Yahua Zhang
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
| | - Fabian Bock
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
| | - Mohammed Ferdaus
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Juan Pablo Arroyo
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
| | - Kristie L Rose
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, USA
- Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Purvi Patel
- Mass Spectrometry Research Center, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jerod S Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Eric Delpire
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alan M Weinstein
- Department of Physiology and Biophysics, Weil Medical College, New York, NY, USA
| | - Ming-Zhi Zhang
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
| | - Raymond C Harris
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA
- Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN, USA
| | - Andrew S Terker
- Division of Nephrology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
- Vanderbilt Center for Kidney Disease, Nashville, TN, USA.
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Indrawinata K, Argiropoulos P, Sugita S. Structural and functional understanding of disease-associated mutations in V-ATPase subunit a1 and other isoforms. Front Mol Neurosci 2023; 16:1135015. [PMID: 37465367 PMCID: PMC10352029 DOI: 10.3389/fnmol.2023.1135015] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 06/09/2023] [Indexed: 07/20/2023] Open
Abstract
The vacuolar-type ATPase (V-ATPase) is a multisubunit protein composed of the cytosolic adenosine triphosphate (ATP) hydrolysis catalyzing V1 complex, and the integral membrane complex, Vo, responsible for proton translocation. The largest subunit of the Vo complex, subunit a, enables proton translocation upon ATP hydrolysis, mediated by the cytosolic V1 complex. Four known subunit a isoforms (a1-a4) are expressed in different cellular locations. Subunit a1 (also known as Voa1), the neural isoform, is strongly expressed in neurons and is encoded by the ATP6V0A1 gene. Global knockout of this gene in mice causes embryonic lethality, whereas pyramidal neuron-specific knockout resulted in neuronal cell death with impaired spatial and learning memory. Recently reported, de novo and biallelic mutations of the human ATP6V0A1 impair autophagic and lysosomal activities, contributing to neuronal cell death in developmental and epileptic encephalopathies (DEE) and early onset progressive myoclonus epilepsy (PME). The de novo heterozygous R740Q mutation is the most recurrent variant reported in cases of DEE. Homology studies suggest R740 deprotonates protons from specific glutamic acid residues in subunit c, highlighting its importance to the overall V-ATPase function. In this paper, we discuss the structure and mechanism of the V-ATPase, emphasizing how mutations in subunit a1 can lead to lysosomal and autophagic dysfunction in neurodevelopmental disorders, and how mutations to the non-neural isoforms, a2-a4, can also lead to various genetic diseases. Given the growing discovery of disease-causing variants of V-ATPase subunit a and its function as a pump-based regulator of intracellular organelle pH, this multiprotein complex warrants further investigation.
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Affiliation(s)
- Karen Indrawinata
- Division of Translational and Experimental Neuroscience, Krembil Brain Institute, University Health Network, Toronto, ON, Canada
| | - Peter Argiropoulos
- Division of Translational and Experimental Neuroscience, Krembil Brain Institute, University Health Network, Toronto, ON, Canada
| | - Shuzo Sugita
- Division of Translational and Experimental Neuroscience, Krembil Brain Institute, University Health Network, Toronto, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
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3
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Schlingmann KP, Renigunta A, Hoorn EJ, Forst AL, Renigunta V, Atanasov V, Mahendran S, Barakat TS, Gillion V, Godefroid N, Brooks AS, Lugtenberg D, Lake J, Debaix H, Rudin C, Knebelmann B, Tellier S, Rousset-Rouvière C, Viering D, de Baaij JHF, Weber S, Palygin O, Staruschenko A, Kleta R, Houillier P, Bockenhauer D, Devuyst O, Vargas-Poussou R, Warth R, Zdebik AA, Konrad M. Defects in KCNJ16 Cause a Novel Tubulopathy with Hypokalemia, Salt Wasting, Disturbed Acid-Base Homeostasis, and Sensorineural Deafness. J Am Soc Nephrol 2021; 32:1498-1512. [PMID: 33811157 PMCID: PMC8259640 DOI: 10.1681/asn.2020111587] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 02/04/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The transepithelial transport of electrolytes, solutes, and water in the kidney is a well-orchestrated process involving numerous membrane transport systems. Basolateral potassium channels in tubular cells not only mediate potassium recycling for proper Na+,K+-ATPase function but are also involved in potassium and pH sensing. Genetic defects in KCNJ10 cause EAST/SeSAME syndrome, characterized by renal salt wasting with hypokalemic alkalosis associated with epilepsy, ataxia, and sensorineural deafness. METHODS A candidate gene approach and whole-exome sequencing determined the underlying genetic defect in eight patients with a novel disease phenotype comprising a hypokalemic tubulopathy with renal salt wasting, disturbed acid-base homeostasis, and sensorineural deafness. Electrophysiologic studies and surface expression experiments investigated the functional consequences of newly identified gene variants. RESULTS We identified mutations in the KCNJ16 gene encoding KCNJ16, which along with KCNJ15 and KCNJ10, constitutes the major basolateral potassium channel of the proximal and distal tubules, respectively. Coexpression of mutant KCNJ16 together with KCNJ15 or KCNJ10 in Xenopus oocytes significantly reduced currents. CONCLUSIONS Biallelic variants in KCNJ16 were identified in patients with a novel disease phenotype comprising a variable proximal and distal tubulopathy associated with deafness. Variants affect the function of heteromeric potassium channels, disturbing proximal tubular bicarbonate handling as well as distal tubular salt reabsorption.
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Affiliation(s)
- Karl P. Schlingmann
- Department of General Pediatrics, Pediatric Nephrology, University Children’s Hospital, Munster, Germany
| | - Aparna Renigunta
- Department of Pediatric Nephrology, Marburg Kidney Research Center, Philipps University, Marburg, Germany
| | - Ewout J. Hoorn
- Division of Nephrology and Transplantation, Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Anna-Lena Forst
- Department of Physiology, Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Vijay Renigunta
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University, Marburg, Germany
| | - Velko Atanasov
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Sinthura Mahendran
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | | | - Valentine Gillion
- Division of Nephrology, Saint-Luc Academic Hospital, Université Catholique Louvain, Brussels, Belgium
| | - Nathalie Godefroid
- Division of Pediatric Nephrology, Saint-Luc Academic Hospital, Université Catholique Louvain, Brussels, Belgium
| | - Alice S. Brooks
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Dorien Lugtenberg
- Department of Human Genetics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jennifer Lake
- Department of Physiology, Mechanism of Inherited Kidney Disorders, University of Zurich, Zurich, Switzerland
| | - Huguette Debaix
- Department of Physiology, Mechanism of Inherited Kidney Disorders, University of Zurich, Zurich, Switzerland
| | - Christoph Rudin
- Department of Pediatric Nephrology, University Children’s Hospital, Basel, Switzerland
| | - Bertrand Knebelmann
- Department of Nephrology-Transplantation, Assistance Publique Hôpitaux de Paris, Hôpital Necker, Paris, France,Reference Center for Hereditary Kidney and Childhood Diseases (MAladies Renales Hereditaires de l'Enfant et de l'Adulte), Paris, France
| | - Stephanie Tellier
- Department of Pediatric Nephrology, and Rheumatology, French Reference Center of Rare Renal Diseases (SORARE), CHU Toulouse, Toulouse, France,Division of Rheumatology, Department of Pediatrics, Centre Hospitalier Universitaire de Toulouse, Toulouse, France
| | - Caroline Rousset-Rouvière
- Department of Multidisciplinary Pediatrics, Pediatric Nephrology Unit, La Timone, University Hospital of Marseille, Marseille, France
| | - Daan Viering
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jeroen H. F. de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Stefanie Weber
- Department of Pediatric Nephrology, Marburg Kidney Research Center, Philipps University, Marburg, Germany
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Alexander Staruschenko
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin,Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin
| | - Robert Kleta
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Paediatric Nephrology, Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, United Kingdom
| | - Pascal Houillier
- Reference Center for Hereditary Kidney and Childhood Diseases (MAladies Renales Hereditaires de l'Enfant et de l'Adulte), Paris, France,Department of Physiology, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France,Department of Renal Physiology, Centre de Recherche des Cordeliers, Institut National de la Santé et de la Recherche Médicale, Sorbonne Université, Université de Paris, Centre National de la Recherche Scientifique, Paris, France
| | - Detlef Bockenhauer
- Department of Renal Medicine, University College London, London, United Kingdom,Department of Paediatric Nephrology, Great Ormond Street Hospital for Children National Health Service Foundation Trust, London, United Kingdom
| | - Olivier Devuyst
- Division of Nephrology, Saint-Luc Academic Hospital, Université Catholique Louvain, Brussels, Belgium,Department of Physiology, Mechanism of Inherited Kidney Disorders, University of Zurich, Zurich, Switzerland
| | - Rosa Vargas-Poussou
- Reference Center for Hereditary Kidney and Childhood Diseases (MAladies Renales Hereditaires de l'Enfant et de l'Adulte), Paris, France,Department of Renal Physiology, Centre de Recherche des Cordeliers, Institut National de la Santé et de la Recherche Médicale, Sorbonne Université, Université de Paris, Centre National de la Recherche Scientifique, Paris, France,Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges-Pompidou, Paris, France
| | - Richard Warth
- Department of Physiology, Medical Cell Biology, University of Regensburg, Regensburg, Germany
| | - Anselm A. Zdebik
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom,Department of Renal Medicine, University College London, London, United Kingdom
| | - Martin Konrad
- Department of General Pediatrics, Pediatric Nephrology, University Children’s Hospital, Munster, Germany
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4
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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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5
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Lopez-Garcia SC, Emma F, Walsh SB, Fila M, Hooman N, Zaniew M, Bertholet-Thomas A, Colussi G, Burgmaier K, Levtchenko E, Sharma J, Singhal J, Soliman NA, Ariceta G, Basu B, Murer L, Tasic V, Tsygin A, Decramer S, Gil-Peña H, Koster-Kamphuis L, La Scola C, Gellermann J, Konrad M, Lilien M, Francisco T, Tramma D, Trnka P, Yüksel S, Caruso MR, Chromek M, Ekinci Z, Gambaro G, Kari JA, König J, Taroni F, Thumfart J, Trepiccione F, Winding L, Wühl E, Ağbaş A, Belkevich A, Vargas-Poussou R, Blanchard A, Conti G, Boyer O, Dursun I, Pınarbaşı AS, Melek E, Miglinas M, Novo R, Mallett A, Milosevic D, Szczepanska M, Wente S, Cheong HI, Sinha R, Gucev Z, Dufek S, Iancu D, Kleta R, Schaefer F, Bockenhauer D. Treatment and long-term outcome in primary distal renal tubular acidosis. Nephrol Dial Transplant 2020; 34:981-991. [PMID: 30773598 DOI: 10.1093/ndt/gfy409] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Primary distal renal tubular acidosis (dRTA) is a rare disorder, and we aimed to gather data on treatment and long-term outcome. METHODS We contacted paediatric and adult nephrologists through European professional organizations. Responding clinicians entered demographic, biochemical, genetic and clinical data in an online form. RESULTS Adequate data were collected on 340 patients (29 countries, female 52%). Mutation testing had been performed on 206 patients (61%); pathogenic mutations were identified in 170 patients (83%). The median (range) presentation age was 0.5 (0-54) years and age at last follow-up was 11.0 (0-70.0) years. Adult height was slightly below average with a mean (SD score) of -0.57 (±1.16). There was an increased prevalence of chronic kidney disease (CKD) Stage ≥2 in children (35%) and adults (82%). Nephrocalcinosis was reported in 88%. Nephrolithiasis was more common with SLC4A1 mutations (42% versus 21%). Thirty-six percent had hearing loss, particularly in ATP6V1B1 (88%). The median (interquartile range) prescribed dose of alkali (mEq/kg/day) was 1.9 (1.2-3.3). Adequate metabolic control (normal plasma bicarbonate and normocalciuria) was achieved in 158 patients (51%), more commonly in countries with higher gross domestic product (67% versus 23%), and was associated with higher height and estimated glomerular filtration rate. CONCLUSION Long-term follow-up from this large dRTA cohort shows an overall favourable outcome with normal adult height for most and no patient with CKD Stage 5. However, 82% of adult patients have CKD Stages 2-4. Importance of adequate metabolic control was highlighted by better growth and renal function but was achieved in only half of patients.
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Affiliation(s)
- Sergio Camilo Lopez-Garcia
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Centre for Nephrology, University College London, London, UK
| | - Francesco Emma
- Division of Nephrology, Bambino Gesù Children's Hospital-IRCCS, Rome, Italy
| | - Stephen B Walsh
- Centre for Nephrology, University College London, London, UK
| | - Marc Fila
- Pediatric Nephrology-CHU Arnaud de Villeneuve, Montpellier University Hospital, Montpellier, France
| | - Nakysa Hooman
- Ali-Asghar Clinical Research Development Center, Iran University of Medical Sciences, Tehran, Iran
| | - Marcin Zaniew
- Department of Pediatrics, University of Zielona Góra, Zielona Góra, Poland
| | | | | | - Kathrin Burgmaier
- Department of Pediatrics, University Hospital of Cologne, Cologne, Germany
| | | | | | | | - Neveen A Soliman
- Department of Pediatrics, Center of Pediatric Nephrology & Transplantation, Kasr Al Ainy School of Medicine, Cairo University, Cairo, Egypt
| | - Gema Ariceta
- Hospital Universitario Vall d'Hebron, Barcelona, Spain
| | - Biswanath Basu
- Division of Pediatric Nephrology, NRS Medical College, Kolkata, India
| | - Luisa Murer
- Pediatric Nephrology, Dialysis and Transplant Unit, Azienda Ospedaliera & University of Padova, Padova, Italy
| | - Velibor Tasic
- University Children's Hospital, Medical School, Skopje, Macedonia
| | - Alexey Tsygin
- National Medical and Research Centre for Children's Health, Moscow, Russia
| | - Stéphane Decramer
- Centre Hospitalier Universitaire de Toulouse, Service de Nephrologie Pediatrique, Hopital des Enfants, Centre De Reference des Maladies Rénales Rares du Sud Ouest, Toulouse, France
| | | | | | - Claudio La Scola
- Nephrology and Dialysis Unit, Department of Woman, Child and Urological Diseases, Azienda Ospedaliero-Universitaria Sant'Orsola-Malpighi, Bologna, Italy
| | | | | | - Marc Lilien
- Wilhelmina Children's Hospital, University Medical Center, Utrecht, The Netherlands
| | | | - Despoina Tramma
- Fourth Pediatric Department, Aristotle University, Thessaloniki, Greece
| | - Peter Trnka
- Lady Cilento Children's Hospital, Brisbane, Australia.,School of Medicine, the University of Queensland, Brisbane, Australia
| | - Selçuk Yüksel
- Department of Pediatric Nephrology, Pamukkale University School of Medicine, Denizli, Turkey
| | - Maria Rosa Caruso
- Nephrology Unit Azienda Ospedaliera, Papa Giovani XXIII, Bergamo, Italy
| | | | - Zelal Ekinci
- Group Florence Nightingale Hospitals, İstanbul, Turkey
| | - Giovanni Gambaro
- Fondazione Policlinico A. Gemelli, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Jameela A Kari
- Pediatric Nephrology Center of Excellence and Pediatric Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Jens König
- University Children's Hospital, Münster, Germany
| | - Francesca Taroni
- Pediatric Nephrology, Dialysis and Transplant Unit, Fondazione IRCCS Ca' Granda-Ospedale Maggiore Policlinico, Milan, Italy
| | | | - Francesco Trepiccione
- Department of Translational Medical Sciences, University of Campania "L. Vanvitelli", Naples, Italy
| | - Louise Winding
- Pediatric Department, Lillebaelt Hospital Kolding, Kolding, Denmark
| | - Elke Wühl
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University Hospital of Heidelberg, Heidelberg, Germany
| | - Ayşe Ağbaş
- Haseki Education and Research Hospital, Istanbul, Turkey
| | | | - Rosa Vargas-Poussou
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Anne Blanchard
- Department of Genetics, Assistance Publique Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Paris, France
| | - Giovanni Conti
- Pediatric Nephrology Unit, AOU Policlinic G Martino, Messina, Italy
| | | | - Ismail Dursun
- Faculty of Medicine, Department of Pediatric Nephrology, Erciyes University, Kayseri, Turkey
| | - Ayşe Seda Pınarbaşı
- Faculty of Medicine, Department of Pediatric Nephrology, Erciyes University, Kayseri, Turkey
| | | | - Marius Miglinas
- Nephrology Centre, Santaros Klinikos, Vilnius University, Vilnius, Lithuania
| | | | - Andrew Mallett
- School of Medicine, the University of Queensland, Brisbane, Australia.,Department of Renal Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia
| | | | | | - Sarah Wente
- Department of Pediatric Nephrology, Hannover Medical School, Hannover, Germany
| | - Hae Il Cheong
- Department of Pediatrics, Seoul University Children's Hospital, Seoul, Korea
| | | | - Zoran Gucev
- Medical School, University Children's Hospital, Skopje, Macedonia
| | - Stephanie Dufek
- Centre for Nephrology, University College London, London, UK
| | - Daniela Iancu
- Centre for Nephrology, University College London, London, UK
| | | | - Robert Kleta
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Centre for Nephrology, University College London, London, UK
| | - Franz Schaefer
- Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, University Hospital of Heidelberg, Heidelberg, Germany
| | - Detlef Bockenhauer
- Department of Paediatric Nephrology, Great Ormond Street Hospital for Children, NHS Foundation Trust, London, UK.,Centre for Nephrology, University College London, London, UK
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6
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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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7
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Koratala A, Ruchi R. Hypokalemia: A potentially life-threatening complication of tenofovir therapy. SAGE Open Med Case Rep 2017; 5:2050313X17741010. [PMID: 29163953 PMCID: PMC5692135 DOI: 10.1177/2050313x17741010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 10/12/2017] [Indexed: 11/20/2022] Open
Abstract
Tenofovir is a nucleotide analog reverse transcriptase inhibitor approved for the treatment of HIV and hepatitis B infections. It is widely prescribed and an integral part of the recommended regimens for the treatment of HIV infection in antiretroviral-naive patients. Tenofovir is implicated in renal proximal tubular dysfunction, which can be associated with Fanconi syndrome and hypokalemia. When the hypokalemia is severe, it can lead to life-threatening complications. We describe the case of a 59-year-old woman who suffered a cardiac arrest secondary to severe hypokalemia from tenofovir use.
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Affiliation(s)
- Abhilash Koratala
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida, Gainesville, FL, USA
| | - Rupam Ruchi
- Division of Nephrology, Hypertension and Renal Transplantation, University of Florida, Gainesville, FL, USA
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8
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Lien YHH. Urine Tests for Chronic Hypokalemia: When in Doubt, Check Urine-Sodium-to-Chloride Ratio. Am J Med 2017; 130:761-762. [PMID: 28359722 DOI: 10.1016/j.amjmed.2017.02.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 02/27/2017] [Indexed: 10/19/2022]
Affiliation(s)
- Yeong-Hau H Lien
- Department of Medicine, College of Medicine, University of Arizona, Tucson; Arizona Kidney Disease and Hypertension Center, Tucson
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9
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Rosner MH, Perazella MA, Choi MJ. American Society of Nephrology quiz and questionnaire 2014: acid-base and electrolyte disorders. Clin J Am Soc Nephrol 2015; 10:530-9. [PMID: 25617429 DOI: 10.2215/cjn.10911114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The Nephrology Quiz and Questionnaire remains an extremely popular session for attendees of the Annual Kidney Week Meeting of the American Society of Nephrology. Once again, in 2014 the conference hall was overflowing with audience members and eager quiz participants. Topics covered by the expert discussants included electrolyte and acid-base disorders, glomerular disease, ESRD/dialysis, and transplantation. Complex cases from each of these categories along with single-best-answer questions were prepared and submitted by the panel of experts. Before the meeting, program directors of United States nephrology training programs and nephrology fellows answered the questions using an Internet-based questionnaire. During the live session, members of the audience tested their knowledge and judgment on a series of case-oriented questions prepared and discussed by the experts. They compared their answers in real time using audience response devices with the answers of the nephrology fellows and training program directors. The correct and incorrect answers were then discussed after the audience responses and the results of the questionnaire were displayed. As always, the audience, lecturers, and moderators enjoyed this educational session. This article recapitulates the acid-base and electrolyte disorders portion of the session and reproduces its educational value for the readers of the Clinical Journal of the American Society of Nephrology. Enjoy the clinical cases and expert discussions.
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Affiliation(s)
- Mitchell H Rosner
- Chairman, Department of Medicine, Division of Nephrology, University of Virginia Health System, Charlottesville, Virginia;
| | - Mark A Perazella
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut; and
| | - Michael J Choi
- Division of Nephrology, Department of Medicine, Johns Hopkins University, Baltimore, Maryland
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The effects of sodium valproate on the renal function of children with epilepsy. Pediatr Nephrol 2014; 29:1131-8. [PMID: 23720013 DOI: 10.1007/s00467-013-2512-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/27/2013] [Accepted: 05/08/2013] [Indexed: 10/26/2022]
Abstract
Sodium valproate is one of the most commonly used drugs to treat epilepsy. However, there is growing evidence that valproate can cause renal tubular injury in children, and there are increasing reports of valproate-induced Fanconi's syndrome where the renal tubules lose their ability to reabsorb electrolytes, urea, glucose and protein. In this review article we attempt to bring together all of the studies conducted to date on the effects of valproate on renal function in epileptic children. The research is generally considered in two themes; the first comprises studies which indicate subclinical tubular injury measured by renal enzymes such as N-acetyl-β-D-glucosaminidase (NAG), and the second comprises clinical reports where Fanconi's syndrome has occurred. This article goes on to analyse the current data and draws on recurring patterns to suggest that a specific subpopulation of severely disabled epileptic children may benefit hugely from the close monitoring of enzymes which are indicative of renal tubular injury, particularly NAG or in the very least periodical urinalysis.
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A case of Fanconi syndrome accompanied by crystal depositions in tubular cells in a patient with multiple myeloma. Kidney Res Clin Pract 2014; 33:112-5. [PMID: 26877961 PMCID: PMC4714179 DOI: 10.1016/j.krcp.2014.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 03/25/2014] [Accepted: 04/18/2014] [Indexed: 11/27/2022] Open
Abstract
Fanconi syndrome (FS) is a rare condition that is characterized by defects in the proximal tubular function. A 48-year-old woman was admitted for evaluation of proteinuria. The patient showed normal anion gap acidosis, normoglycemic glycosuria, hypophosphatemia, and hypouricemia. Thus, her condition was compatible with FS. The M peak was found behind the beta globulin region in urine protein electrophoresis. Upon bone marrow examination, we found that 24% of cells were CD138+ plasma cells with kappa restriction. From a kidney biopsy, we found crystalline inclusions within proximal tubular epithelial cells. Thereafter, she was diagnosed with FS accompanied by multiple myeloma. The patient received chemotherapy and autologous stem cell transplantation, and obtained very good partial hematologic response. However, proximal tubular dysfunction was persistent until 1 year after autologous stem cell transplantation. In short, we report a case of FS accompanied by multiple myeloma, demonstrating crystalline inclusion in proximal tubular cells on kidney biopsy.
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Min HK, Kim EO, Lee SJ, Chang YK, Suh KS, Yang CW, Kim SY, Hwang HS. Rifampin-associated tubulointersititial nephritis and Fanconi syndrome presenting as hypokalemic paralysis. BMC Nephrol 2013; 14:13. [PMID: 23320835 PMCID: PMC3558351 DOI: 10.1186/1471-2369-14-13] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 01/14/2013] [Indexed: 11/17/2022] Open
Abstract
Background Rifampin is one of the most important drugs in first-line therapies for tuberculosis. The renal toxicity of rifampin has been reported sporadically and acute tubulointerstitial nephritis (ATIN) is a frequent histological finding. We describe for the first time a case of ATIN and Fanconi syndrome presenting as hypokalemic paralysis, associated with the use of rifampin. Case presentation A 42-year-old man was admitted with sudden-onset lower extremity paralysis and mild renal insufficiency. He had been treated for pulmonary tuberculosis with isoniazid, rifampin, and ethambutol for 2 months. Laboratory tests revealed proteinuria, profound hypokalemia, hyperchloremic metabolic acidosis with a normal anion gap, positive urine anion gap, hypophosphatemia with hyperphosphaturia, hypouricemia with hyperuricosuria, glycosuria with normal serum glucose level, generalized aminoaciduria, and β2-microglobulinuria. A kidney biopsy revealed findings typical of ATIN and focal granular deposits of immunoglubulin A and complement 3 in the glomeruli and tubules. Electron microscopy showed epithelial foot process effacement and electron-dense deposits in the subendothelial and mesangial spaces. Cessation of rifampin resolved the patient’s clinical presentation of Fanconi syndrome, and improved his renal function and proteinuria. Conclusion This case demonstrates that rifampin therapy can be associated with Fanconi syndrome presenting as hypokalemic paralysis, which is a manifestation of ATIN. Kidney function and the markers of proximal tubular injury should be carefully monitored in patients receiving rifampin.
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Affiliation(s)
- Hong Ki Min
- Division of Nephrology, Department of Internal Medicine, The Catholic University of Korea, Seoul, Korea
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Holick MF. Osteomalacia and rickets. Rheumatology (Oxford) 2011. [DOI: 10.1016/b978-0-323-06551-1.00199-8] [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] Open
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Yang SS, Chu P, Lin YF, Chen A, Lin SH. Aristolochic acid-induced Fanconi's syndrome and nephropathy presenting as hypokalemic paralysis. Am J Kidney Dis 2002; 39:E14. [PMID: 11877594 DOI: 10.1053/ajkd.2002.31425] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hypokalemic paralysis rarely is seen as the presenting feature in patients with Fanconi's syndrome. We describe a 60-year-old man who presented with the inability to ambulate on awakening in the morning. The pertinent history revealed he had consumed Chinese herbs for leg edema for 5 months. Physical examination was unremarkable except for extracellular fluid volume depletion and total paralysis of both lower extremities. Laboratory investigation showed hypokalemia (1.8 mEq/L), hyperchloremic metabolic acidosis (Cl-, 111 mEq/L, and HCO3-, 14.0 mEq/L), hypophosphatemia (0.9 mg/dL) with hyperphosphaturia, hypouricemia (1.3 mg/dL) with hyperuricosuria, and glycosuria, consistent with Fanconi's syndrome. Mild renal insufficiency (serum creatinine, 1.7 mg/dL) also was noticed. Blood and urine screens for heavy metals, autoantibodies, and monoclonal gammopathy were negative. A renal biopsy specimen revealed typical findings of aristolochic acid-associated nephropathy. Aristolochic acids were detected in the consumed Chinese herbs. This case highlights that consumption of Chinese herbs containing aristolochic acids may cause Fanconi's syndrome and should be considered as a cause of hypokalemic paralysis.
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Affiliation(s)
- Sung-Sen Yang
- Division of Nephrology, Department of Medicine, and Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
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Halperin ML, Kamel KS. Dynamic interactions between integrative physiology and molecular medicine: The key to understand the mechanism of action of aldo sterone in the kidney. Can J Physiol Pharmacol 2000. [DOI: 10.1139/y00-039] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our objective is to illustrate how an approach that integrates new insights from molecular biology and traditional physiology can lead to the development of new concepts. This dynamic interaction is illustrated by examining the steps taken to improve our understanding of the renal actions of aldosterone. We began by defining the big picture of what aldosterone does in the kidney. This led to the conclusion that aldosterone must at times become a sodium chloride-retaining hormone, while at other times it must function primarily or exclusively as a kaliuretic hormone. The second step was to define the major molecular actions of this hormone. Acting on the principal cells in the cortical collecting duct (CCD), aldosterone leads to the insertion of active epithelial sodium ion channels (ENaC) in their luminal membranes. This active ENaC, however, does not distinguish between the two major renal actions of aldosterone. Accordingly, we returned to integrative physiology and examined a possible role of renal and non-renal events. We implicated the potential importance of the delivery of bicarbonate ions to the CCD to determine which effect of aldosterone will become manifest. This, however, required that we reconsider some of the traditional views in interpretation of acid-base balance. At the clinical level, this global view can help us understand why, for example, a low dietary intake of potassium salts might predispose a person to an elevated blood pressure. Using a similar approach, it is possible to understand how the risk of the formation of kidney stones can be minimized.Key words: acid-base, hypertension, integrative physiology, kidney stones, potassium, sodium.
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Affiliation(s)
- F J Gennari
- Department of Medicine, University of Vermont College of Medicine, Burlington 05401, USA
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Clarke BL, Wynne AG, Wilson DM, Fitzpatrick LA. Osteomalacia associated with adult Fanconi's syndrome: clinical and diagnostic features. Clin Endocrinol (Oxf) 1995; 43:479-90. [PMID: 7586624 DOI: 10.1111/j.1365-2265.1995.tb02621.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
OBJECTIVE Osteomalacia associated with adult acquired Fanconi's syndrome is thought to result from hypophosphataemia and relative 1,25-dihydroxyvitamin D deficiency. We have followed the clinical and diagnostic features of patients with osteomalacia associated with adult Fanconi's syndrome, with particular emphasis on their responses to treatment with calcium, phosphate and vitamin D. DESIGN Retrospective Mayo Clinic case-note review from 1975 to 1994 and prospective follow-up study, combined with literature review. PATIENTS Eleven patients (7 male, 4 female) were identified who satisfied criteria for diagnosis of osteomalacia and adult Fanconi's syndrome. Twenty-five additional patients were identified in a literature review from 1954 to the present. METHODS Clinical history and physical examination, serum and urine bone and mineral parameter, X-ray radiography and iliac crest bone histomorphometry. RESULTS All patients presented with typical symptoms of osteomalacia, including lower extremity or low back bone pain, and all had fractures, pseudofractures, and/or bone demineralization on X-ray radiography. Osteomalacia and Fanconi's syndrome were diagnosed concurrently in 10 patients, whereas osteomalacia preceded diagnosis of Fanconi's syndrome by 5 years in one patient. Pre-treatment bone biopsies in 9 of the 11 patients demonstrated increased osteoid surface, volume and width. In the one patient labelled with tetracycline prior to biopsy, mineralization lag time was prolonged at 111 days (normal 19.2 +/- 1.0 days). Hypophosphataemia, inappropriately low 1,25-dihydroxyvitamin D levels, renal insufficiency, and chronic acidosis due to bicarbonate leak and uraemia, contributed to the osteomalacia in these patients. Secondary hyperparathyroidism was present in two patients. Eight of the 11 patients with osteomalacia associated with Fanconi's syndrome had monoclonal disorders, including multiple myeloma or lymphoma, many of them manifest by light-chain proteinuria. Over a mean patient follow-up period of 46 months (range 1-239 months), patients responded symptomatically to calcium, phosphate, and vitamin D replacement typically within 1-6 months. In 8 patients in whom follow-up data were available, post-treatment serum phosphate and 1,25-dihydroxyvitamin D levels improved in the setting of stable mild renal insufficiency; only one patient developed end-stage renal failure after 20 years, suggesting that these patients do not invariably progress rapidly to renal failure. CONCLUSIONS Regardless of the underlying cause, osteomalacia associated with adult acquired Fanconi's syndrome appears to respond well to calcium, phosphate, and vitamin D replacement. These patients do not appear to necessarily require 1,25-dihydroxyvitamin D replacement.
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Affiliation(s)
- B L Clarke
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA
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Kay L, Satoshi H, Chan JC. Perturbations in Potassium Balance. Clin Lab Med 1993. [DOI: 10.1016/s0272-2712(18)30467-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Stedwell RE, Allen KM, Binder LS. Hypokalemic paralyses: a review of the etiologies, pathophysiology, presentation, and therapy. Am J Emerg Med 1992; 10:143-8. [PMID: 1586409 DOI: 10.1016/0735-6757(92)90048-3] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Acute hypokalemic paralysis is an uncommon cause of acute weakness. Morbidity and mortality associated with unrecognized disease include respiratory failure and death. Hence, it is imperative for physicians to be knowledgeable about the causes of hypokalemic paralysis, and consider them diagnostically. The hypokalemic paralyses represent a heterogeneous group of disorders with a final common pathway presenting as acute weakness and hypokalemia. Most cases are due to familial hypokalemic paralysis; however, sporadic cases are associated with diverse underlying etiologies including thyrotoxic periodic paralysis, barium poisoning, renal tubular acidosis, primary hyperaldosteronism, licorice ingestion, and gastrointestinal potassium losses. The approach to the patient with hypokalemic paralysis includes a vigorous search for the underlying etiology and potassium replacement therapy. Further therapy depends on the etiology of the hypokalemia. Disposition depends on severity of symptoms, degree of hypokalemia, and chronicity of disease.
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Affiliation(s)
- R E Stedwell
- Department of Emergency Medicine, Texas Tech University Health Sciences Center, El Paso 79905
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Abstract
The adrenal cortex is functionally a three-dimensional gland that secretes glucocorticoids, mineralocorticoids, and sex steroids. Of these three classes of steroids only the gluco- and mineralocorticoid hormones are necessary to sustain life. The availability of sensitive and specific radioimmunoassays has permitted accurate measurement of practically every steroid hormone secreted by the adrenal cortex. As in other endocrinopathies, suppression studies are employed when hyperfunction is suspected, while provocative tests are used to detect hypofunction. These dynamic studies enable the clinician to evaluate the functional status of the adrenal cortex. The anatomic configuration of the adrenal cortices is delineated by high-resolution computed tomography (and magnetic resonance imaging), obviating the need for invasive procedures such as venography or arteriography. The disorders of the adrenal cortex can be viewed from the dual perspectives of hyperfunction and hypofunction. Clinical expressions of hyperfunctional adrenocortical syndromes include Cushing's syndrome, primary hyperaldosteronism, and the adrenogenital syndrome. The expressions of hypofunctional syndromes include Addison's disease and selective hypoaldosteronism. The diagnosis and treatment of these disorders are outlined in this issue.
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Affiliation(s)
- C R Kannan
- Rush-Presbyterian-St. Luke's Medical Center, Chicago, Illinois
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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]
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Abstract
Potassium, largely an intracellular cation, contributes to the regulation of cellular volume, to tissue growth and metabolic synthesis of proteins and nucleic acids, and to the integrity of electrical properties of excitable tissues as well as nonexcitable, transporting epithelia. Potassium balance is closely regulated by a variety of nonrenal and renal mechanisms. When potassium losses are sufficient to induce hypokalemia, either through nonrenal or renal causes, profound adverse effects on neuromuscular, cardiac, vascular, and renal tissues may ensue. The diagnostic approach is straightforward, and therapy must be directed to replenish losses without inducing a rapid, excessive, and potentially fatal increase in the potassium concentration of the serum.
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Gonick HC. Pathophysiology of human proximal tubular transport defects. KLINISCHE WOCHENSCHRIFT 1982; 60:1201-11. [PMID: 6292569 DOI: 10.1007/bf01716723] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The generalized proximal tubular transport abnormalities comprising the Fanconi syndrome (glycosuria, generalized aminoaciduria, the proximal form of renal tubular acidosis, and increased renal clearance of phosphate, urate, calcium, magnesium, and potassium) may be ascribed to interference with "sodiumlinked" active transport. Evidence is presented that the majority of conditions known to cause Fanconi syndrome in man or experimental animals are associated with inhibitors of the renal Na-K-ATPase-ATP transport system.
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Abstract
Renal tubular acidosis is not one entity but several. Even though all its forms are characterized by the kidney's inability to excrete an appropriately acid urine, the mechanism of the defect, its laboratory and clinical manifestations, and its management vary considerably. One type can cause disabling complications in various organ systems, while another is generally asymptomatic. Differential diagnosis is straightforward, and treatment effective.
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Abstract
The infusion of 55 mumoles/kg/min of L-lysine monohydrochloride increased mean fractional bicarbonate excretion (CHCO3/GFR) from 0.01 to 0.29. This massive bicarbonaturia was observed in the absence of any significant fall in GFR or kidney cortex ATP content. Kaliuresis and urinary PCO2 also increased markedly while phosphaturia remained minimal. CHCO3/GFR reached 0.52 during the infusion of 110 mumoles/kg/min of L-lysine monohydrochloride and 0.65 when carbonic anhydrase inhibition was superimposed. Bicarbonaturia remained minimal during the infusion of 55 mumoles/kg/min of L-lysine dihydrochloride. However the same amount of isoelectric L-lysine and sodium L-lysinate increased CHCO3/GFR to 0.68 and 0.76, respectively. In dogs with ligated renal pedicles, a 1:1 relationship was observed between cellular entry of lysine and the combined shift of sodium and potassium from cell to extracellular fluid. Marked accumulation of lysine was observed in the kidney following the infusion of either L-lysine monohydrochloride or L-lysine dihydrochloride. This study demonstrates that lysine inhibits in the proximal tubule the fraction of bicarbonate reabsorption which is not mediated by carbonic anhydrase activity. This effect is best explained by trapping of hydrogen ions in the tubular cell following luminal and antiluminal entry of lysine in unionized form. The possible role of lysine as a poorly reabsorbable cation is also recognized.
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McSherry E, Morris RC. Attainment and maintenance of normal stature with alkali therapy in infants and children with classic renal tubular acidosis. J Clin Invest 1978; 61:509-27. [PMID: 621287 PMCID: PMC372562 DOI: 10.1172/jci108962] [Citation(s) in RCA: 223] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Growth was evaluated in a group of 10 infants and children with familial or idiopathic classic renal tubular acidosis in whom alkali therapy was initiated at ages ranging from 8 days to 9.5 yr and administered at dosage schedules documented to sustain correction of acidosis in at least four prolonged observation periods on the Pediatric Clinical Research Ward. When alkali therapy was begun, six patients (four infants and two children) were stunted (height <2.5 SD below mean). Of the four who were not, two infants were too young (<2 wk of age) to have become stunted, and two children had been documented earlier to be nonacidotic. At the start of alkali therapy, the heights of the patients correlated inversely with the maximal possible duration of prior acidosis. WITH SUSTAINED ALKALI THERAPY: (a) each patient attained and maintained normal stature; (b) the mean height of the 10 patients increased from the 1.4+/-4 to the 37.0+/-33 percentile (of a normal age- and sex-matched population); (c) the mean height reached the 69th percentile in the eight patients whose heights could be analyzed according to parental prediction (Tanner technique); (d) the rate of growth increased two- to threefold, and normal heights were attained within 6 mo of initiating alkali therapy in the stunted infants and within 3 yr in the stunted children; (e) the height attained correlated inversely with the maximal possible duration of acidosis (before alkali therapy) only in those patients in whom alkali therapy was started after 6 mo of age, and not in those treated earlier. The amount of alkali required to sustain correction of acidosis increased substantially during the course of treatment in each patient. The maximal alkali requirement ranged from 4.8 to 14.1 meq/kg per day, and in each patient its amount was determined principally by the magnitude of renal bicarbonate wasting.
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Sebastian A, Schambelan M, Lindenfeld S, Morris RC. Amelioration of metabolic acidosis with fludrocortisone therapy in hyporeninemic hypoaldosteronism. N Engl J Med 1977; 297:576-83. [PMID: 18672 DOI: 10.1056/nejm197709152971104] [Citation(s) in RCA: 111] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In four patients with renal hyperchloremic acidosis and hyperkalemia, hyporeninemic hypoaldosteronism and chronic renal insufficiency (glomerular filtration rates of 13, 31, 35 and 44 ml per minute per 1.73 m2), prolonged administration of fludrocortisone increased urinary potassium and net acid excretion, corrected hyperkalemia and substantially ameliorated acidosis. Except in the patient with the lowest glomerular filtration rate, the increased net acid excretion was due mostly to increased ammonium excretion. Urine pH decreased initially in each patient, but in the three patients with the highest filtration rates, it increased subsequently as ammonium excretion increased, indicating that renal ammonia production increased. Urinary ammonium excretion correlated inversely with serum potassium concentration and did not decrease on discontinuation of therapy if hyperkalemia was prevented from recurring. In patients with renal acidosis and hyporeninemic hypoaldosteronism, administration of mineralocorticoid hormone can augment both renal hydrogen-ion secretion and, by correction of hyperkalemia, renal ammonia production, and thereby ameliorate metabolic acidosis.
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Sebastian A, McSherry E, Morris RC. Impaired renal conservation of sodium and chloride during sustained correction of systemic acidosis in patients with type 1, classic renal tubular acidosis. J Clin Invest 1976; 58:454-69. [PMID: 783200 PMCID: PMC333201 DOI: 10.1172/jci108490] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
In 10 patients with classic renal tubular acidosis in whom correction of acidosis was sustained with orally administered potassium bicarbonate, renal conservation of sodium was evaluated when dietary intake of sodium was restricted to 9--13 meq/day. In five patients, renal conservation of sodium was impaired by at least one criterion of impairment. In the remaining patients, renal conservation of sodium appeared to be relatively well-maintained, but an impairment could not be excluded. In each of six patients studied during induced water diuresis, including two in whom renal conservation of sodium was not unequivocally impaired, the minimal urinary concentrations of sodium were inappropriately high and the urinary excretion rates of sodium were flow-dependent. These results provide direct evidence that an abnormality in renal transport of sodium can occur in classic renal tubular acidosis, and compel a reconsideration of the pathophysiology of disordered renal transport of sodium in this disorder. The results indicate that in at least some patients with classic renal tubular acidosis impaired renal conservation of sodium is not exclusively a reversible consequence of the renal acidification defect. These findings raise the question whether renal transport of sodium is unimpaired in any patients with classic renal tubular acidosis. In the presently studied patients, the impairment in renal conservation of sodium appeared to be in part the consequence of an impaired ability of the vasopressin-responsive segments of the distal nephron to generate and maintain appropriately steep transepithelial sodium concentration gradients.
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Taher SM, Anderson RJ, McCartney R, Popovtzer MM, Schrier RW. Renal tubular acidosis associated with toluene "sniffing". N Engl J Med 1974; 290:765-8. [PMID: 4815223 DOI: 10.1056/nejm197404042901403] [Citation(s) in RCA: 118] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Halperin ML, Goldstein MB, Haig A, Johnson MD, Stinebaugh BJ. Studies on the pathogenesis of type I (distal) renal tubular acidosis as revealed by the urinary PCO2 tensions. J Clin Invest 1974; 53:669-77. [PMID: 4812435 PMCID: PMC333046 DOI: 10.1172/jci107604] [Citation(s) in RCA: 111] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
This study was designed to investigate the pathogenesis of type I (distal) renal tubular acidosis. Urinary and blood Pco(2) tensions were determined when the pH of the urine was equal to or exceeded the corresponding blood pH. This provided an indication of net hydrogen ion secretion in the distal nephron. In 16 normal subjects, the Pco(2) of the urine exceeded blood values (U-B Pco(2)) by 32.7+/-3.1 mm Hg. In contrast, the urinary Pco(2) tensions in 10 patients with type I (distal) renal tubular acidosis were not significantly greater than blood values (U-B Pco(2) = 2.0+/-2.2 mm Hg). These results indicate that type I (distal) renal tubular acidosis is caused by failure of the cells of the distal nephron to secrete hydrogen ions rather than to gradient-limited hydrogen ion addition to the urine. This is suggested by the fact that urinary Pco(2) levels should be higher than blood Pco(2) levels when hydrogen ions are secreted into urine containing bicarbonate in the distal nephron and they were not in this study despite the presence of a favorable hydrogen ion gradient (tubular fluid pH exceeded blood pH).
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MESH Headings
- Acidosis, Renal Tubular/classification
- Acidosis, Renal Tubular/drug therapy
- Acidosis, Renal Tubular/etiology
- Acidosis, Renal Tubular/genetics
- Acidosis, Renal Tubular/immunology
- Acidosis, Renal Tubular/metabolism
- Acidosis, Renal Tubular/urine
- Acute Kidney Injury/complications
- Adrenal Insufficiency/complications
- Alkalies/therapeutic use
- Animals
- Bicarbonates/blood
- Bicarbonates/urine
- Cell Membrane Permeability
- Diuresis
- Female
- Gluconates/pharmacology
- Humans
- Hydrogen/metabolism
- Hydrogen-Ion Concentration
- Hyperparathyroidism/complications
- Kidney Failure, Chronic/complications
- Kidney Tubules, Distal/metabolism
- Male
- Metabolism, Inborn Errors/complications
- Nephrons/metabolism
- Uremia/complications
- Urine
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McSherry E, Sebastian A, Morris RC. Renal tubular acidosis in infants: the several kinds, including bicarbonate-wasting, classic renal tubular acidosis. J Clin Invest 1972; 51:499-514. [PMID: 5011097 PMCID: PMC302155 DOI: 10.1172/jci106838] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In four infants with renal tubular acidosis (RTA), including three with apparently classic RTA and one with Fanconi syndrome (FS), the physiologic character of the renal acidification defect was investigated. In two of the infants with apparently classic RTA, the acidification defect was physiologically separable from that described in both adult patients and children with classic RTA (type 1 RTA) in the following ways. (a) The fractional excretion of filtered bicarbonate (C(HCO3)/C(ln)) was not trivial but substantial (6-9%), as well as relatively fixed, over a broad range of plasma bicarbonate concentrations (15-26 mmoles/liter). (b) This value of C(HCO3)/C(ln), combined with a normal or near normal glomerular filtration rate, translated to renal bicarbonate wasting (RBW). (c) RBW at normal plasma bicarbonate concentrations was the major cause of acidosis, and its magnitude was the major determinant of corrective alkali therapy (5-9 mEq/kg per day), just as in the patient with FS, who was found to have type 2 ("proximal") RTA. (d) Persistence of RBW at substantially reduced plasma bicarbonate concentrations, which did not occur in FS, accounted for the spontaneous occurrence of severe acidosis and its rapid recurrence after reduction in alkali therapy. (e) During severe acidosis the urinary pH was >7, a finding reported frequently in infants with apparently classic RTA and "alkali-resistant" acidosis but rarely in adult patients with classic RTA. Continued supplements of potassium were required to maintain normokalemia during sustained correction of acidosis with alkali therapy. Yet, in at least two of the three infants with apparently classic RTA, but in distinction from the patient with FS and other patients with type 2 RTA, fractional excretion of filtered potassium decreased when plasma bicarbonate was experimentally increased to normal values. In one of the two infants with apparently classic RTA and RBW, C(HCO3)/C(ln) and the therapeutic alkali requirement decreased concomitantly and progressively over 2 yr, but RBW continued. Renal tubular acidosis has persisted in all four patients for at least 3 yr, and in three for 4 years.
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Sebastian A, McSherry E, Morris RC. Renal potassium wasting in renal tubular acidosis (RTA): its occurrence in types 1 and 2 RTA despite sustained correction of systemic acidosis. J Clin Invest 1971; 50:667-78. [PMID: 5101785 PMCID: PMC291975 DOI: 10.1172/jci106537] [Citation(s) in RCA: 77] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
IN TWO PATIENTS WITH CLASSIC RENAL TUBULAR ACIDOSIS (RTA) AND IN TWO PATIENTS WITH RTA ASSOCIATED WITH THE FANCONI SYNDROME, RENAL POTASSIUM WASTING PERSISTED DESPITE SUSTAINED CORRECTION OF ACIDOSIS: (a) during moderate degrees of hypokalemia, daily urinary excretion of potassium exceeded 80 mEq in each patient; (b) during more severe degrees of hypokalemia, daily urinary excretion of potassium exceeded 40 mEq in two patients and 100 mEq in another. These urinary excretion rates of potassium are more than twice those observed in potassium-depleted normal subjects with even minimal degrees of hypokalemia. The persistence of renal potassium wasting may have resulted in part from hyperaldosteronism, since urinary aldosterone was frankly increased in two patients and was probably abnormally high in the others relative to the degree of their potassium depletion. The hyperaldosteronism persisted despite sustained correction of acidosis, a normal sodium intake, and no reduction in measured plasma volume, and was not associated with hypertension; its cause was not defined. In the two patients with classic RTA, neither renal potassium wasting nor hyperaldosteronism could be explained as a consequence of a gradient restriction on renal H(+) - Na(+) exchange because the urinary pH remained greater than, or approximately equal to, the normal arterial pH or considerably greater than the minimal urinary pH attained during acidosis. The findings provide no support for the traditional view that renal potassium wasting in either classic RTA or RTA associated with the Fanconi syndrome is predictably corrected solely by sustained correction of acidosis with alkali therapy.
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