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Kunchur MG, Mauch TJ, Parkanzky M, Rahilly LJ. A review of renal tubular acidosis. J Vet Emerg Crit Care (San Antonio) 2024; 34:325-355. [PMID: 39023331 DOI: 10.1111/vec.13407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 10/14/2022] [Accepted: 11/11/2022] [Indexed: 07/20/2024]
Abstract
OBJECTIVE To review the current scientific literature on renal tubular acidosis (RTA) in people and small animals, focusing on diseases in veterinary medicine that result in secondary RTA. DATA SOURCES Scientific reviews and original research publications on people and small animals focusing on RTA. SUMMARY RTA is characterized by defective renal acid-base regulation that results in normal anion gap hyperchloremic metabolic acidosis. Renal acid-base regulation includes the reabsorption and regeneration of bicarbonate in the renal proximal tubule and collecting ducts and the process of ammoniagenesis. RTA occurs as a primary genetic disorder or secondary to disease conditions. Based on pathophysiology, RTA is classified as distal or type 1 RTA, proximal or type 2 RTA, type 3 RTA or carbonic anhydrase II mutation, and type 4 or hyperkalemic RTA. Fanconi syndrome comprises proximal RTA with additional defects in proximal tubular function. Extensive research elucidating the genetic basis of RTA in people exists. RTA is a genetic disorder in the Basenji breed of dogs, where the mutation is known. Secondary RTA in human and veterinary medicine is the sequela of diseases that include immune-mediated, toxic, and infectious causes. Diagnosis and characterization of RTA include the measurement of urine pH and the evaluation of renal handling of substances that should affect acid or bicarbonate excretion. CONCLUSIONS Commonality exists between human and veterinary medicine among the types of RTA. Many genetic defects causing primary RTA are identified in people, but those in companion animals other than in the Basenji are unknown. Critically ill veterinary patients are often admitted to the ICU for diseases associated with secondary RTA, or they may develop RTA while hospitalized. Recognition and treatment of RTA may reverse tubular dysfunction and promote recovery by correcting metabolic acidosis.
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Affiliation(s)
| | - Teri Jo Mauch
- University of Nebraska Medical Center and Children's Hospital, Omaha, Nebraska, USA
- University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | | | - Louisa J Rahilly
- Cape Cod Veterinary Specialists, Buzzards Bay, Massachusetts, USA
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2
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Berman AR, Specht AJ, Castro RA, Cooke KL, Gilor S, Harris AN. Correlation between urine anion gap and urine ammonia-creatinine ratio in healthy cats and cats with kidney disease. J Vet Intern Med 2024; 38:1068-1073. [PMID: 38348890 PMCID: PMC10937481 DOI: 10.1111/jvim.17002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/22/2024] [Indexed: 03/16/2024] Open
Abstract
BACKGROUND Ammonium excretion decreases as kidney function decreases in several species, including cats, and may have predictive or prognostic value in patients with chronic kidney disease (CKD). Urine ammonia measurement is not readily available in clinical practice, and urine anion gap (UAG) has been proposed as a surrogate test. OBJECTIVES Evaluate the correlation between urine ammonia-to-creatinine ratio (UACR) and UAG in healthy cats and those with CKD and determine if a significant difference exists between UAG of healthy cats and cats with CKD. ANIMALS Urine samples collected from healthy client-owned cats (n = 59) and those with stable CKD (n = 17). METHODS Urine electrolyte concentrations were measured using a commercial chemistry analyzer and UAG was calculated as ([sodium] + [potassium]) - [chloride]. Urine ammonia and creatinine concentrations had been measured previously using commercially available enzymatic assays and used to calculate UACR. Spearman's rank correlation coefficient between UAG and UACR was calculated for both groups. The UAG values of healthy cats and cats with CKD were assessed using the Mann-Whitney test (P < .05). RESULTS The UAG was inversely correlated with UACR in healthy cats (P < .002, r0 = -0.40) but not in cats with CKD (P = .55; r0 = -0.15). A significant difference was found between UAG in healthy cats and those with CKD (P < .001). CONCLUSIONS AND CLINICAL IMPORTANCE The UAG calculation cannot be used as a substitute for UACR in cats. The clinical relevance of UAG differences between healthy cats and those with CKD remains unknown.
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Affiliation(s)
- Alyssa R. Berman
- Department of Small Animal Clinical ScienceUniversity of Florida College of Veterinary MedicineGainesvilleFloridaUSA
| | - Andrew J. Specht
- Department of Small Animal Clinical ScienceUniversity of Florida College of Veterinary MedicineGainesvilleFloridaUSA
| | - Rebeca A. Castro
- Department of Small Animal Clinical ScienceUniversity of Florida College of Veterinary MedicineGainesvilleFloridaUSA
| | - Kirsten L. Cooke
- Department of Small Animal Clinical ScienceUniversity of Florida College of Veterinary MedicineGainesvilleFloridaUSA
| | - Shir Gilor
- Department of Comparative, Diagnostics and Population MedicineUniversity of Florida College of Veterinary MedicineGainesvilleFloridaUSA
| | - Autumn N. Harris
- Department of Small Animal Clinical ScienceUniversity of Florida College of Veterinary MedicineGainesvilleFloridaUSA
- Division of Nephrology, Hypertension and Renal TransplantationUniversity of Florida College of MedicineGainesvilleFloridaUSA
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3
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Mhlana N, Korf M, Davids MR, Chothia MY. Distal renal tubular acidosis in a patient with Hashimoto's thyroiditis: a case report. Biochem Med (Zagreb) 2023; 33:020802. [PMID: 37324116 PMCID: PMC10231765 DOI: 10.11613/bm.2023.020802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023] Open
Abstract
Renal tubular acidosis (RTA) is a rare disorder that can be inherited or acquired, and results in an inability of the kidneys to maintain normal acid-base balance. We present a case of recurrent, severe hypokalaemia and rhabdomyolysis in a young woman who had an associated normal anion gap metabolic acidosis and was subsequently diagnosed with distal RTA associated with Hashimoto's thyroiditis. Distal RTA associated with Hashimoto's thyroiditis is rare and probably develops because of autoimmune-mediated mechanisms, causing an inability of the H+-ATPase pump in alpha-intercalated cells of the cortical collecting duct to secrete H+, with subsequent failure of urinary acidification. In this case, this hypothesis was supported by the exclusion of common genetic mutations associated with distal RTA. We illustrate that utilizing a systematic, physiology-based approach for challenging electrolyte and acid-base disorders enables identification of the root cause and underlying disease mechanisms.
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Affiliation(s)
- Nontembiso Mhlana
- Division of Nephrology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Marizna Korf
- Department of Chemical Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University and National Health Laboratory Services, Cape Town, South Africa
| | - Mogamat Razeen Davids
- Division of Nephrology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Mogamat-Yazied Chothia
- Division of Nephrology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
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4
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Rehman MZ, Melamed M, Harris A, Shankar M, Rosa RM, Batlle D. Urinary Ammonium in Clinical Medicine: Direct Measurement and the Urine Anion Gap as a Surrogate Marker During Metabolic Acidosis. ADVANCES IN KIDNEY DISEASE AND HEALTH 2023; 30:197-206. [PMID: 36868734 DOI: 10.1053/j.akdh.2022.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 12/15/2022] [Indexed: 03/05/2023]
Abstract
Ammonium is the most important component of urinary acid excretion, normally accounting for about two-third of net acid excretion. In this article, we discuss urine ammonium not only in the evaluation of metabolic acidosis but also in other clinical conditions such as chronic kidney disease. Different methods to measure urine NH4+ that have been employed over the years are discussed. The enzymatic method used by clinical laboratories in the United States to measure plasma ammonia via the glutamate dehydrogenase can be used for urine ammonium. The urine anion gap calculation can be used as a rough marker of urine ammonium in the initial bedside evaluation of metabolic acidosis such as in distal renal tubular acidosis. Urine ammonium measurements, however, should be made more available in clinical medicine for a precise evaluation of this important component of urinary acid excretion.
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Affiliation(s)
- Mohammed Z Rehman
- Division of Nephrology and Hypertension, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Michal Melamed
- Department of Medicine (Nephrology), Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY
| | - Autumn Harris
- Department of Small Animal Clinical Sciences College of Veterinary Medicine, Gainesville, FL
| | - Mythri Shankar
- Department of Nephrology, Institute of Nephro-urology, Bengaluru, India
| | - Robert M Rosa
- Division of Nephrology and Hypertension, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Daniel Batlle
- Division of Nephrology and Hypertension, Northwestern University Feinberg School of Medicine, Chicago, IL.
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5
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Uribarri J, Goldfarb DS, Raphael KL, Rein JL, Asplin JR. Beyond the Urine Anion Gap: In Support of the Direct Measurement of Urinary Ammonium. Am J Kidney Dis 2022; 80:667-676. [PMID: 35810828 DOI: 10.1053/j.ajkd.2022.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 05/10/2022] [Indexed: 02/02/2023]
Abstract
Ammonium is a major urinary buffer that is necessary for the normal excretion of the daily acid load. Its urinary rate of excretion (UNH4) may be increased several fold in the presence of extrarenal metabolic acidosis. Therefore, measurement of UNH4 can provide important clues about causes of metabolic acidosis. Because UNH4 is not commonly measured in clinical laboratories, the urinary anion gap (UAG) was proposed as its surrogate about 4 decades ago, and it is still frequently used for that purpose. Several published studies strongly suggest that UAG is not a good index of UNH4 and support the concept that direct measurement of UNH4 is an important parameter to define in clinical nephrology. Low UNH4 levels have recently been found to be associated with a higher risk of metabolic acidosis, loss of kidney function, and death in persons with chronic kidney disease, while surrogates like the UAG do not recapitulate this risk. In order to advance the field it is necessary for the medical community to become more familiar with UNH4 levels in a variety of clinical settings. Herein, we review the literature, searching for available data on UNH4 under normal and various pathological conditions, in an attempt to establish reference values to interpret UNH4 results if and when UNH4 measurements become available as a routine clinical test. In addition, we present original data in 2 large populations that provide further evidence that the UAG is not a good predictor of UNH4. Measurement of urine NH4 holds promise to aid clinicians in the care of patients, and we encourage further research to determine its best diagnostic usage.
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Affiliation(s)
- Jaime Uribarri
- Renal Division, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.
| | | | - Kalani L Raphael
- Oregon Health & Science University and VA Portland Health Care System, Portland, Oregon
| | - Joshua L Rein
- Renal Division, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - John R Asplin
- Litholink Corporation, Laboratory Corporation of America Holdings, Chicago, Illinois
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6
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Hoenig MP, Lecker SH, William JH. What's Old Is New Again: Harnessing the Power of Original Experiments to Learn Renal Physiology. Adv Chronic Kidney Dis 2022; 29:486-492. [PMID: 36371110 DOI: 10.1053/j.ackd.2022.03.006] [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: 12/18/2021] [Revised: 03/02/2022] [Accepted: 03/22/2022] [Indexed: 11/10/2022]
Abstract
Although medical schools across the United States have updated their curricula to incorporate active learning techniques, there has been little discussion on the nature of the content presented to students. Here, we share detailed examples of our experience in using original experiments to lay the groundwork for foundational concepts in renal physiology and pathophysiology. We believe that this approach offers distinct advantages over standard case-based teaching by (1) starting with simple concepts, (2) analyzing memorable visuals, (3) increasing graphical literacy, (4) translating observations to "rules," (5) encouraging critical thinking, and (6) providing historical perspective to the study of medicine. Although we developed this content for medical students, we have found that many of these lessons are also appropriate as foundational concepts for residents and fellows and serve as an excellent springboard for increasingly complex discussions of clinical applications of physiology. The use of original experiments for teaching and learning in renal physiology harnesses skills in critical thinking and provides a solid foundation that will help learners with subsequent case-based learning in the preclerkship curriculum and in the clinical arena.
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Affiliation(s)
- Melanie P Hoenig
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
| | - Stewart H Lecker
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Jeffrey H William
- Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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7
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Gruzdys V, Cahoon K, Pearson L, Raphael KL. Measurement of Urinary Ammonium Using a Commercially Available Plasma Ammonium Assay. KIDNEY360 2022; 3:926-932. [PMID: 36128493 PMCID: PMC9438425 DOI: 10.34067/kid.0000262022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 02/09/2022] [Indexed: 01/10/2023]
Abstract
Background Determination of urinary ammonium excretion is helpful in evaluating patients with acid-base disorders, chronic kidney disease, and nephrolithiasis. However, urinary ammonium levels are only measured by specialized laboratories in the United States, limiting widespread implementation. We evaluated the performance of a plasma ammonium assay to quantify urinary ammonium excretion and also determined ammonium stability under a variety of conditions. Methods An enzymatic plasma ammonium assay (Randox) was modified to measure urinary ammonium concentration. Urine samples were diluted 40-fold and then assayed on an Abbott Architect ci8200 analyzer. Assay precision, limit of quantitation, and linearity were determined. The method was compared against the formalin titration method, and stability studies were conducted at different temperatures and pH. Results After dilution, the assay had total precision of 18% at 2.54 mmol/L, 5% at 15.58 mmol/L, and 2% at 29.49 mmol/L, with a limit of quantitation of 2.92 mmol/L. Assay performance was linear in the range of 0.7-45 mmol/L. Method comparison against the formalin method showed a slope of 0.98 and intercept of -0.37 mmol/L. Urinary ammonium was determined to be stable for 48 hours at room temperature and for 9 days at 4°C and -20°C at pH 5.6-6.3. Ammonium was less stable at pH 3.8 and 8.5. When stored at -80°C, urinary ammonium was stable for at least 24 months. Conclusions The modified enzymatic plasma ammonium assay reliably quantifies urine ammonium at physiologic concentrations. It compares well with the formalin titration method and is suitable for routine clinical use on an automated chemistry analyzer.
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Affiliation(s)
| | | | - Lauren Pearson
- Department of Pathology, University of Utah School of Medicine, Health Sciences Center, Salt Lake City, Utah
| | - Kalani L. Raphael
- Division of Nephrology and Hypertension, Department of Medicine, Oregon Health and Science University and VA Portland Health Care System, Portland, Oregon
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8
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Díaz-Anadón L, Cardo L, Santos F, Gil-Peña H. Evaluation of urinary acidification in children: Clinical utility. Front Pediatr 2022; 10:1051481. [PMID: 36389372 PMCID: PMC9660234 DOI: 10.3389/fped.2022.1051481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 10/10/2022] [Indexed: 11/13/2022] Open
Abstract
The kidney plays a fundamental role in acid-base homeostasis by reabsorbing the filtered bicarbonate and by generating new bicarbonate, to replace that consumed in the buffering of non-volatile acids, a process that leads to the acidification of urine and the excretion of ammonium (NH4 +). Therefore, urine pH (UpH) and urinary NH4 + (UNH4 +) are valuable parameters to assess urinary acidification. The adaptation of automated plasma NH4 + quantification methods to measure UNH4 + has proven to be an accurate and feasible technique, with diverse potential indications in clinical practice. Recently, reference values for spot urine NH4 +/creatinine ratio in children have been published. UpH and UNH4 +, aside from their classical application in the study of metabolic acidosis, have shown to be useful in the identification of incomplete distal renal tubular acidosis (dRTA), an acidification disorder, without overt metabolic acidosis, extensively described in adults, and barely known in children, in whom it has been found to be associated to hypocitraturia, congenital kidney abnormalities and growth impairment. In addition, a low UNH4 + in chronic kidney disease (CKD) is a risk factor for glomerular filtration decay and mortality in adults, even in the absence of overt metabolic acidosis. We here emphasize on the need of measuring UpH and UNH4 + in pediatric population, establishing reference values, as well as exploring their application in metabolic acidosis, CKD and disorders associated with incomplete dRTA, including growth retardation of unknown cause.
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Affiliation(s)
- Lucas Díaz-Anadón
- Division of Pediatric Nephrology, Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain.,Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain
| | - Leire Cardo
- Clinical Biochemistry Department, Laboratory of Medicine, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain
| | - Fernando Santos
- Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain
| | - Helena Gil-Peña
- Division of Pediatric Nephrology, Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Asturias, Spain.,Department of Medicine, Faculty of Medicine, University of Oviedo, Oviedo, Asturias, Spain.,Section of Pediatrics, Instituto de Investigación Sanitaria del Principado de Asturias (ISPA), Oviedo, Asturias, Spain
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9
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Adrianowycz SE, Castro RA, Specht AJ, Harris AN. Establishment of an RI for the urine ammonia-to-creatinine ratio in dogs. Vet Clin Pathol 2021; 50:597-602. [PMID: 34854107 PMCID: PMC9299733 DOI: 10.1111/vcp.13032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/09/2021] [Accepted: 04/24/2021] [Indexed: 11/30/2022]
Abstract
Background Ammonia is produced and excreted by the kidney, contributing to systemic acid‐base homeostasis through the production of bicarbonate. Disorders of acid‐base balance can lead to many clinical problems and measuring ammonia excretion helps in determining if the kidneys are responding to acid‐base challenges appropriately. Reference intervals are integral to clinical decision‐making, and there is no current RI for the urine ammonia‐to‐creatinine ratio (UACR) in dogs. Objective This study aimed to generate an RI for the UACR in healthy adult dogs. Methods The study used adult, client‐owned dogs that were presented to the University of Florida Primary Care and Dentistry service (n = 60). Physical examinations were performed and serum chemistry and urinalysis samples were obtained. Urine ammonia and creatinine concentrations were determined. Dogs were excluded if there were significant abnormalities in either their urinalysis or serum chemistry results. The RI for the UACR was calculated according to the recommendation of the American Society for Veterinary Clinical Pathology. Data were evaluated for correlation with serum bicarbonate, weight, age, and sex. Results The RIs for the UACR were 0.16‐23.69 with 90% confidence intervals for the lower and upper limits of (0.13‐1.17) and (20.50‐23.75), respectively. No significant impact of age, sex, or weight was found. There was no discernable relationship between serum bicarbonate and UACR. Conclusions Establishing an RI for UACR in healthy adult dogs will allow for further studies to determine if alterations are observed during specific disease states.
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Affiliation(s)
- Sarah E Adrianowycz
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
| | - Rebeca A Castro
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
| | - Andrew J Specht
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
| | - Autumn N Harris
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA.,Division of Nephrology, Hypertension and Renal Transplantation, College of Medicine, University of Florida, Gainesville, Florida, USA
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10
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Abstract
Two papers, one in 1986 and another one in 1988, reported a strong inverse correlation between urinary anion gap (UAG) and urine ammonia excretion (UNH4) in patients with metabolic acidosis and postulated that UAG could be used as an indirect measure of UNH4 This postulation has persisted until now and is widely accepted. In this review, we discuss factors regulating UAG and examine published evidence to uncover errors in the postulate and the design of the original studies. The essential fact is that, in the steady state, UAG reflects intake of Na, K, and Cl. Discrepancy between intake and urinary output of these electrolytes (i.e, UAG) indicates selective extrarenal loss of these electrolytes or nonsteady state. UNH4 excretion, which depends, in the absence of renal dysfunction, mainly on the daily acid load, has no consistent relationship to UAG either theoretically or in reality. Any correlation between UAG and UNH4, when observed, was a fortuitous correlation and cannot be extrapolated to other situations. Furthermore, the normal value of UAG has greatly increased over the past few decades, mainly due to increases in dietary intake of potassium and widespread use of sodium salts with anions other than chloride as food additives. The higher normal values of UAG must be taken into consideration in interpreting UAG.
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Affiliation(s)
- Jaime Uribarri
- Renal Division, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Man S. Oh
- Renal Division, Department of Medicine, State University of New York at Downstate, Brooklyn, New York
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11
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Kamel KS, Halperin ML. Use of Urine Electrolytes and Urine Osmolality in the Clinical Diagnosis of Fluid, Electrolytes, and Acid-Base Disorders. Kidney Int Rep 2021; 6:1211-1224. [PMID: 34013099 PMCID: PMC8116912 DOI: 10.1016/j.ekir.2021.02.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Accepted: 02/01/2021] [Indexed: 01/16/2023] Open
Abstract
We discuss the use of urine electrolytes and urine osmolality in the clinical diagnosis of patients with fluid, electrolytes, and acid-base disorders, emphasizing their physiological basis, their utility, and the caveats and limitations in their use. While our focus is on information obtained from measurements in the urine, clinical diagnosis in these patients must integrate information obtained from the history, the physical examination, and other laboratory data.
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Affiliation(s)
- Kamel S. Kamel
- Renal Division, St. Michael’s Hospital and The University of Toronto, Toronto, Ontario, Canada
- Keenan Research Center in the Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - Mitchell L. Halperin
- Renal Division, St. Michael’s Hospital and The University of Toronto, Toronto, Ontario, Canada
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12
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Abstract
A large body of work in animals and human beings supports the hypothesis that metabolic acidosis has a deleterious effect on the progression of kidney disease. Alkali therapy, whether pharmacologically or through dietary intervention, appears to slow CKD progression, but an appropriately powered randomized controlled trial with a low risk of bias is required to reach a more definitive conclusion. Recent work on urinary ammonium excretion has shown that the development of prognostic tools related to acidosis is not straightforward, and that application of urine markers such as ammonium may require more nuance than would be predicted based on our understanding of the pathophysiology.
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Affiliation(s)
- Wei Chen
- Department of Medicine, Nephrology Division, Albert Einstein College of Medicine, Bronx, NY; Department of Medicine, Nephrology Division, University of Rochester School of Medicine and Dentistry, Rochester, NY.
| | - David S Levy
- Department of Medicine, Nephrology Division, University of Rochester School of Medicine and Dentistry, Rochester, NY
| | - Matthew K Abramowitz
- Department of Medicine, Nephrology Division, Albert Einstein College of Medicine, Bronx, NY
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13
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Mato EPM, Essop MF, Owira PMO. Effects of naringenin on renal expression of organic cation transporter 1 and 2 proteins and metformin disposition in diabetic rats. J Funct Foods 2019. [DOI: 10.1016/j.jff.2019.05.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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14
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Abstract
Renal tubular acidosis should be suspected in poorly thriving young children with hyperchloremic and hypokalemic normal anion gap metabolic acidosis, with/without syndromic features. Further workup is needed to determine the type of renal tubular acidosis and the presumed etiopathogenesis, which informs treatment choices and prognosis. The risk of nephrolithiasis and calcinosis is linked to the presence (proximal renal tubular acidosis, negligible stone risk) or absence (distal renal tubular acidosis, high stone risk) of urine citrate excretion. New formulations of slow-release alkali and potassium combination supplements are being tested that are expected to simplify treatment and lead to sustained acidosis correction.
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Affiliation(s)
- Robert Todd Alexander
- Department of Pediatrics and Physiology, Stollery Children's Hospital, 11405-87 Avenue, Edmonton, Alberta T6G 1C9, Canada
| | - Martin Bitzan
- Division of Nephrology, Department of Pediatrics, The Montreal Children's Hospital, McGill University Health Centre, Room B RC.6651, Montreal, Quebec H4A 3J1, Canada; Al Jalila Children's Hospital, Al Jadaf PO Box 7662, Dubai, UAE.
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15
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Uduman J, Yee J. Pseudo-Renal Tubular Acidosis: Conditions Mimicking Renal Tubular Acidosis. Adv Chronic Kidney Dis 2018; 25:358-365. [PMID: 30139462 DOI: 10.1053/j.ackd.2018.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hyperchloremic metabolic acidosis, particularly renal tubular acidosis, can pose diagnostic challenges. The laboratory phenotype of a low total carbon dioxide content, normal anion gap, and hyperchloremia may be misconstrued as hypobicarbonatemia from renal tubular acidosis. Several disorders can mimic renal tubular acidosis, and these must be appropriately diagnosed to prevent inadvertent and inappropriate application of alkali therapy. Key physiologic principles and limitations in the assessment of renal acid handling that can pose diagnostic challenges are enumerated.
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16
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Kurtz I. Renal Tubular Acidosis: H +/Base and Ammonia Transport Abnormalities and Clinical Syndromes. Adv Chronic Kidney Dis 2018; 25:334-350. [PMID: 30139460 PMCID: PMC6128697 DOI: 10.1053/j.ackd.2018.05.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Renal tubular acidosis (RTA) represents a group of diseases characterized by (1) a normal anion gap metabolic acidosis; (2) abnormalities in renal HCO3- absorption or new renal HCO3- generation; (3) changes in renal NH4+, Ca2+, K+, and H2O homeostasis; and (4) extrarenal manifestations that provide etiologic diagnostic clues. The focus of this review is to give a general overview of the pathogenesis of the various clinical syndromes causing RTA with a particular emphasis on type I (hypokalemic distal RTA) and type II (proximal) RTA while reviewing their pathogenesis from a physiological "bottom-up" approach. In addition, the factors involved in the generation of metabolic acidosis in both type I and II RTA are reviewed highlighting the importance of altered renal ammonia production/partitioning and new HCO3- generation. Our understanding of the underlying tubular transport and extrarenal abnormalities has significantly improved since the first recognition of RTA as a clinical entity because of significant advances in clinical acid-base chemistry, whole tubule and single-cell H+/base transport, and the molecular characterization of the various transporters and channels that are functionally affected in patients with RTA. Despite these advances, additional studies are needed to address the underlying mechanisms involved in hypokalemia, altered ammonia production/partitioning, hypercalciuria, nephrocalcinosis, cystic abnormalities, and CKD progression in these patients.
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Affiliation(s)
- Ira Kurtz
- Division of Nephrology, David Geffen School of Medicine, and Brain Research Institute, UCLA, Los Angeles, CA.
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Raphael KL, Gilligan S, Ix JH. Urine Anion Gap to Predict Urine Ammonium and Related Outcomes in Kidney Disease. Clin J Am Soc Nephrol 2018; 13:205-212. [PMID: 29097482 PMCID: PMC5967420 DOI: 10.2215/cjn.03770417] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Accepted: 09/25/2017] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND OBJECTIVES Low urine ammonium excretion is associated with ESRD in CKD. Few laboratories measure urine ammonium, limiting clinical application. We determined correlations between urine ammonium, the standard urine anion gap, and a modified urine anion gap that includes sulfate and phosphate and compared risks of ESRD or death between these ammonium estimates and directly measured ammonium. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS We measured ammonium, sodium, potassium, chloride, phosphate, and sulfate from baseline 24-hour urine collections in 1044 African-American Study of Kidney Disease and Hypertension participants. We evaluated the cross-sectional correlations between urine ammonium, the standard urine anion gap (sodium + potassium - chloride), and a modified urine anion gap that includes urine phosphate and sulfate in the calculation. Multivariable-adjusted Cox models determined the associations of the standard urine anion gap and the modified urine anion gap with the composite end point of death or ESRD; these results were compared with results using urine ammonium as the predictor of interest. RESULTS The standard urine anion gap had a weak and direct correlation with urine ammonium (r=0.18), whereas the modified urine anion gap had a modest inverse relationship with urine ammonium (r=-0.58). Compared with the highest tertile of urine ammonium, those in the lowest urine ammonium tertile had higher risk of ESRD or death (hazard ratio, 1.46; 95% confidence interval, 1.13 to 1.87) after adjusting for demographics, GFR, proteinuria, and other confounders. In comparison, participants in the corresponding standard urine anion gap tertile did not have higher risk of ESRD or death (hazard ratio, 0.82; 95% confidence interval, 0.64 to 1.07), whereas the risk for those in the corresponding modified urine anion gap tertile (hazard ratio, 1.32; 95% confidence interval, 1.03 to 1.68) approximated that of directly measured urine ammonium. CONCLUSIONS Urine anion gap is a poor surrogate of urine ammonium in CKD unless phosphate and sulfate are included in the calculation. Because the modified urine anion gap merely estimates urine ammonium and requires five measurements, direct measurements of urine ammonium are preferable in CKD.
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Affiliation(s)
- Kalani L. Raphael
- Division of Nephrology, Department of Internal Medicine, University of Utah Health, Salt Lake City, Utah
- Nephrology Section, Veterans Affairs Salt Lake City Health Care System, Salt Lake City, Utah
| | - Sarah Gilligan
- Division of Nephrology, Department of Internal Medicine, University of Utah Health, Salt Lake City, Utah
| | - Joachim H. Ix
- Division of Nephrology-Hypertension, Department of Medicine and
- Division of Preventive Medicine, Department of Family Medicine and Public Health, University of California, San Diego, California; and
- Nephrology Section, Veterans Affairs San Diego Healthcare System, San Diego, California
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18
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Affiliation(s)
- Daniel Batlle
- Division of Nephrology/Hypertension, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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Nagami GT, Hamm LL. Regulation of Acid-Base Balance in Chronic Kidney Disease. Adv Chronic Kidney Dis 2017; 24:274-279. [PMID: 29031353 DOI: 10.1053/j.ackd.2017.07.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 07/28/2017] [Indexed: 11/11/2022]
Abstract
The kidneys play a major role in the regulation of acid-base balance by reabsorbing bicarbonate filtered by the glomeruli and excreting titratable acids and ammonia into the urine. In CKD, with declining kidney function, acid retention and metabolic acidosis occur, but the extent of acid retention depends not only on the degree of kidney impairment but also on the dietary acid load. Acid retention can occur even when the serum bicarbonate level is apparently normal. With reduced kidney function, acid transport processes in the surviving nephrons are augmented but as disease progresses ammonia excretion and, in some individuals, the ability to reabsorb bicarbonate falls, whereas titratable acid excretion is preserved until kidney function is severely impaired. Urinary ammonia levels are used to gauge the renal response to acid loads and are best assessed by direct measurement of urinary ammonia levels rather than by indirect assessments. In individuals with acidosis from CKD, an inappropriately low degree of ammonia excretion points to the pathogenic role of impaired urinary acid excretion. The presence of a normal bicarbonate level in CKD complicates the interpretation of the urinary ammonia excretion as such individuals could be in acid-base balance or could be retaining acid without manifesting a low bicarbonate level. At this time, the decision to give bicarbonate supplementation in CKD is reserved for those with a bicarbonate level of 22 mEq/L, but because of potential harm of overtreatment, supplementation should be adjusted to maintain a bicarbonate level of <26 mEq/L.
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Abstract
PURPOSE OF REVIEW To facilitate the understanding and knowledge of renal tubular acidosis by providing a summarized information on the known clinical and biochemical characteristics of this group of diseases, by updating the genetic and molecular bases of the primary forms renal tubular acidosis and by examining some issues regarding the diagnosis of distal renal tubular acidosis (RTA) in the daily clinical practice. RECENT FINDINGS The manuscript presents recent findings on the potential of next-generation sequencing to disclose new pathogenic variants in patients with a clinical diagnosis of primary RTA and negative Sanger sequencing of known genes. The current review emphasizes the importance of measuring urinary ammonium for a correct clinical approach to the patients with metabolic acidosis and discusses the diagnosis of incomplete distal RTA. SUMMARY We briefly update the current information on RTA, put forward the need of additional studies in children to validate urinary indexes used in the diagnosis of RTA and offer a perspective on diagnostic genetic tests.
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Rastegar M, Nagami GT. Non-Anion Gap Metabolic Acidosis: A Clinical Approach to Evaluation. Am J Kidney Dis 2016; 69:296-301. [PMID: 28029394 DOI: 10.1053/j.ajkd.2016.09.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 09/20/2016] [Indexed: 11/11/2022]
Abstract
Acid-base disturbances can result from kidney or nonkidney disorders. We present a case of high-volume ileostomy output causing large bicarbonate losses and resulting in a non-anion gap metabolic acidosis. Non-anion gap metabolic acidosis can present as a form of either acute or chronic metabolic acidosis. A complete clinical history and physical examination are critical initial steps to begin the evaluation process, followed by measuring serum electrolytes with a focus on potassium level, blood gas, urine pH, and either direct or indirect urine ammonium concentration. The present case was selected to highlight the differential diagnosis of a non-anion gap metabolic acidosis and illustrate a systematic approach to this problem.
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Affiliation(s)
- Mandana Rastegar
- Nephrology Section, VA Greater Los Angeles Healthcare System, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Glenn T Nagami
- Nephrology Section, VA Greater Los Angeles Healthcare System, David Geffen School of Medicine at UCLA, Los Angeles, CA.
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22
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Urinary Strong Ion Difference as a Marker of Renal Dysfunction. A Retrospective Analysis. PLoS One 2016; 11:e0156941. [PMID: 27258049 PMCID: PMC4892615 DOI: 10.1371/journal.pone.0156941] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 05/23/2016] [Indexed: 12/21/2022] Open
Abstract
Introduction The kidneys play a crucial role in the regulation of electrolytes and acid-base homeostasis. Urinary Strong Ion Difference (SIDu = NaU + KU—ClU) represents an important aspect of renal acid-base regulation. We evaluated the role of SIDu as a marker of renal dysfunction in critically ill patients. Materials and Methods Patients admitted to the Medical Intensive Care Unit with a diagnosis of AKI for whom concomitant urinary samples available for SIDu calculation were retrospectively reviewed and staged according to KDIGO criteria for 3 days from inclusion. Patients were classified as Recovered (R-AKI) or Persistent-AKI (P-AKI) whether they exited KDIGO criteria within the 3-day observation period or not. A control group with normal renal function and normal serum acid-base and electrolytes was prospectively recruited in order to identify reference SIDu values. Results One-hundred-and-forty-three patients with a diagnosis of AKI were included: 77 with R-AKI, and 66 with P-AKI. Thirty-six controls were recruited. Patients with P-AKI had more severe renal dysfunction and higher mortality than patients with R-AKI (SCr 2.23(IQR:1.68–3.45) and 1.81(IQR1.5–2.5) mg/dl respectively, p<0.001; 24-h UO 1297(950) and 2100(1094) ml respectively, p = 0.003); 30-d mortality, 39% and 13% respectively; p<0.001). SIDu significantly differed between groups, with rising values from controls to P-AKI groups (16.4(12), 30(24) and 47.3(21.5) mEq/l respectively, p<0.001). Discussion SIDu may be a simple and inexpensive tool in AKI patients’ evaluation. Further research is needed to evaluate the ability of SIDu to identify patients with renal dysfunction before derangements in serum creatinine or urine output are observed.
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23
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Drug-induced acid-base disorders. Pediatr Nephrol 2015; 30:1407-23. [PMID: 25370778 DOI: 10.1007/s00467-014-2958-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 08/28/2014] [Accepted: 09/03/2014] [Indexed: 10/24/2022]
Abstract
The incidence of acid-base disorders (ABDs) is high, especially in hospitalized patients. ABDs are often indicators for severe systemic disorders. In everyday clinical practice, analysis of ABDs must be performed in a standardized manner. Highly sensitive diagnostic tools to distinguish the various ABDs include the anion gap and the serum osmolar gap. Drug-induced ABDs can be classified into five different categories in terms of their pathophysiology: (1) metabolic acidosis caused by acid overload, which may occur through accumulation of acids by endogenous (e.g., lactic acidosis by biguanides, propofol-related syndrome) or exogenous (e.g., glycol-dependant drugs, such as diazepam or salicylates) mechanisms or by decreased renal acid excretion (e.g., distal renal tubular acidosis by amphotericin B, nonsteroidal anti-inflammatory drugs, vitamin D); (2) base loss: proximal renal tubular acidosis by drugs (e.g., ifosfamide, aminoglycosides, carbonic anhydrase inhibitors, antiretrovirals, oxaliplatin or cisplatin) in the context of Fanconi syndrome; (3) alkalosis resulting from acid and/or chloride loss by renal (e.g., diuretics, penicillins, aminoglycosides) or extrarenal (e.g., laxative drugs) mechanisms; (4) exogenous bicarbonate loads: milk-alkali syndrome, overshoot alkalosis after bicarbonate therapy or citrate administration; and (5) respiratory acidosis or alkalosis resulting from drug-induced depression of the respiratory center or neuromuscular impairment (e.g., anesthetics, sedatives) or hyperventilation (e.g., salicylates, epinephrine, nicotine).
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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.
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Abstract
Toluene sniffing, frequently described under the generic category of "glue sniffing," is a potential cause of normal anion gap metabolic acidosis due to distal renal tubular acidosis. Urine anion gap is used to diagnose metabolic acidosis of a normal anion gap variety; however, pitfalls exist when using urine anion gap in the setting of toluene sniffing. We present the case of a young woman who had a normal anion gap metabolic acidosis due to toluene sniffing and an unexpectedly low urine anion gap. In such a scenario, the urine anion gap will underestimate the rate of ammonia excretion when the conjugate bases of acids other than HCl are excreted in large quantities. Estimation of the urine osmolal gap will provide a more accurate ammonia excretion rate in these circumstances. The challenges in interpretation of the urine anion gap and ammonia excretion in the setting of distal renal tubular acidosis due to toluene toxicity are discussed.
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27
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Abstract
Renal tubular acidosis (RTA) is a group of transport defects in the reabsorption of bicarbonate, the excretion of hydrogen ion (H+), or both, resulting in systemic acidosis and hypokalemia with a normal glomerular filtration rate. Although isolated proximal (type 2) or distal (type 1) tubular pathologies are well characterized, a combined pathology leading to type 3 RTA is very rare. Here, we report a case of type 3 RTA, using an algorithmic approach to classify a scenario of hypokalemic metabolic acidosis in the setting of episodic flaccid paralysis.
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Affiliation(s)
- R P Goswami
- Department of Medicine, Institute of Post Graduate Medical Education and Research and Seth Sukhlal Karnani Hospital, Kolkata, India
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28
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Kraut JA, Madias NE. Differential diagnosis of nongap metabolic acidosis: value of a systematic approach. Clin J Am Soc Nephrol 2012; 7:671-9. [PMID: 22403272 DOI: 10.2215/cjn.09450911] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Nongap metabolic acidosis is a common form of both acute and chronic metabolic acidosis. Because derangements in renal acid-base regulation are a common cause of nongap metabolic acidosis, studies to evaluate renal acidification often serve as the mainstay of differential diagnosis. However, in many cases, information obtained from the history and physical examination, evaluation of the electrolyte pattern (to determine if a nongap acidosis alone or a combined nongap and high anion gap metabolic acidosis is present), and examination of the serum potassium concentration (to characterize the disorder as hyperkalemic or hypokalemic in nature) is sufficient to make a presumptive diagnosis without more sophisticated studies. If this information proves insufficient, indirect estimates or direct measurement of urinary NH(4)(+) concentration, measurement of urine pH, and assessment of urinary HCO(3)(-) excretion can help in establishing the diagnosis. This review summarizes current information concerning the pathophysiology of this electrolyte pattern and the value and limitations of all of the diagnostic studies available. It also provides a systematic and cost-effective approach to the differential diagnosis of nongap metabolic acidosis.
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Affiliation(s)
- Jeffrey A Kraut
- Medical and Research Services, Veterans Administration Greater Los Angeles Healthcare System, California 90073, USA.
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29
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Halperin ML, Kamel KS. Some observations on the clinical approach to metabolic acidosis. J Am Soc Nephrol 2010; 21:894-7. [PMID: 20488948 DOI: 10.1681/asn.2009080794] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Affiliation(s)
- Mitchell L Halperin
- Keenan Research Centre, Li Ka Shing Knowledge Instituet, St. Michael's Hospital, Shuter Wing, Room 5-078, 30 Bond Street, Toronto, Ontario, M5B 1W8, Canada.
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31
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Abstract
The anion gap (AG) measurement is a very useful tool in the evaluation of patients with acid-base disorders. Once metabolic acidosis is identified, AG will provide the important first step in the differential diagnosis of disorders that either increase the AG and those that leave the AG unchanged. Delta gap is the comparison between change (delta) in the AG and the change (delta) in bicarbonate (HCO(3)(-)). Delta ratio, defined as delta AG:delta HCO(3)(-) is usually 1:1 in patients with an uncomplicated high AG acidosis. A value below 1:1 suggests a combined high and normal AG acidosis. A value above 2:1 suggests a combined metabolic alkalosis and a high AG acidosis. Urine AG (unmeasured anions-unmeasured cations) is an indirect estimate of the urine NH(4)(+) excretion. It is typically negative in patients with normal AG metabolic acidosis secondary to diarrhoea. Utilisation of AG calculations helps clinicians in identifying and treating acid-base disorders.
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Affiliation(s)
- P Reddy
- Department of Medicine, University of Florida College of Medicine, Jacksonville, FL 32209, USA.
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32
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Abstract
Renal tubular acidoses (RTA) comprises of a group of disorders characterized by a low capacity for net acid excretion and persistent hyperchloremic, metabolic acidosis. The RTAs are classified into chiefly three types (types 1,2 and 4) based on clinical and laboratory characteristics. Correct diagnosis involves careful evaluation, including exclusion of other entities causing acidosis. A variety of tests are required to be administered in a stepwise fashion for the diagnosis and characterization of RTA.
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Affiliation(s)
- Arvind Bagga
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, New Delhi, India. arvindbagga@ hotmail.com
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Schoolwerth AC, Kaneko TM, Sedlacek M, Block CA, Remillard BD. CRITICAL CARE ISSUES FOR THE NEPHROLOGIST: Acid-base Disturbances in the Intensive Care Unit: Metabolic Acidosis. Semin Dial 2006; 19:492-5. [PMID: 17150049 DOI: 10.1111/j.1525-139x.2006.00211.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article will discuss metabolic acidosis and, to a lesser extent, metabolic alkalosis in the ICU setting. A classification and clinical approach will be the focus.
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Affiliation(s)
- Anton C Schoolwerth
- Section of Nephrology and Hypertension, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA.
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34
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Groeneveld JHM, Sijpkens YWJ, Lin SH, Davids MR, Halperin ML. An approach to the patient with severe hypokalaemia: the potassium quiz. QJM 2005; 98:305-16. [PMID: 15760922 DOI: 10.1093/qjmed/hci046] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The objective of this teaching session with Professor McCance is to develop an approach to the management of patients with a very low plasma potassium (K(+)) concentration (P(K)). The session begins with a quiz based on six recent medical consultations for a P(K) < 2 mmol/l. Professor McCance outlined how he would proceed with his diagnosis and therapy, using the synopsis that described each patient. This approach was then applied to a new patient, a 69-year-old woman who had a large volume of dependent oedema and developed a severe degree of weakness and hypokalaemia during more aggressive diuretic therapy that included a K(+)-sparing diuretic. The initial challenge for Professor McCance was to deduce why the K(+)-sparing diuretic was not effective in this patient. He also needed to explain why the P(K) was so low on admission.
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Affiliation(s)
- J H M Groeneveld
- Department of Nephrology, Leiden University Medical Center, The Netherlands
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35
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Abstract
Acid-base problem solving has been an integral part of medical practice in recent generations. Diseases discovered in the last 30-plus years, for example, Bartter syndrome and Gitelman syndrome, D-lactic acidosis, and bulimia nervosa, can be diagnosed according to characteristic acid-base findings. Accuracy in acid-base problem solving is a direct result of a reproducible, systematic approach to arterial pH, partial pressure of carbon dioxide, bicarbonate concentration, and electrolytes. The 'Rules of Five' is one tool that enables clinicians to determine the cause of simple and complex disorders, even triple acid-base disturbances, with consistency. In addition, other electrolyte abnormalities that accompany acid-base disorders, such as hypokalemia, can be incorporated into algorithms that complement the Rules and contribute to efficient problem solving in a wide variety of diseases. Recently urine electrolytes have also assisted clinicians in further characterizing select disturbances. Acid-base patterns, in many ways, can serve as a 'common diagnostic pathway' shared by all subspecialties in medicine. From infectious disease (eg, lactic acidemia with highly active antiviral therapy therapy) through endocrinology (eg, Conn's syndrome, high urine chloride alkalemia) to the interface between primary care and psychiatry (eg, bulimia nervosa with multiple potential acid-base disturbances), acid-base problem solving is the key to unlocking otherwise unrelated diagnoses. Inasmuch as the Rules are clinical tools, they are applied throughout this monograph to diverse pathologic conditions typical in contemporary practice.
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Abstract
Hypokalemia with paralysis (HP) is a potentially reversible medical emergency. It is primarily the result of either hypokalemic periodic paralysis (HPP) caused by an enhanced shift of potassium (K(+)) into cells or non-HPP resulting from excessive K(+) loss. Failure to make a distinction between HPP and non-HPP could lead to improper management. The use of spot urine for K(+) excretion rate and evaluation of blood acid-base status could be clinically beneficial in the diagnosis and management. A very low rate of K(+) excretion coupled with the absence of a metabolic acid-base disorder suggests HPP, whereas a high rate of K(+) excretion accompanied by either metabolic alkalosis or metabolic acidosis favors non-HPP. The therapy of HPP requires only small doses of potassium chloride (KCl) to avoid rebound hyperkalemia. In contrast, higher doses of KCl should be administered to replete the large K(+) deficiency in non-HPP.
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Affiliation(s)
- Shih-Hua Lin
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, R.O.C.
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Fall PJ. A stepwise approach to acid-base disorders. Practical patient evaluation for metabolic acidosis and other conditions. Postgrad Med 2000; 107:249-50, 253-4, 257-8 passim. [PMID: 10728149 DOI: 10.3810/pgm.2000.03.957] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Acid-base disorders can usually be approached by following the steps outlined in the text and doing the calculations shown in the box on page 257. Clues about the underlying disorder can be obtained from history taking and physical examination. Assessment of pH, PaCO2, and HCO3- allows determination of whether a primary metabolic or respiratory disorder is present. Calculation of the predicted compensatory response for simple acid-base disorders might suggest the presence of an additional disease process if compensation is not appropriate. Calculation of the various gaps can be helpful in differential diagnosis (i.e., anion gap for diagnosis of metabolic acidosis, delta anion gap for diagnosis of high-anion-gap metabolic acidosis, and urine anion gap for diagnosis of a non-anion gap metabolic acidosis). Most acid-base problems can be solved with use of the stepwise approach described.
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Affiliation(s)
- P J Fall
- Medical College of Georgia School of Medicine, Section of Nephrology, St, Augusta 30912-3140, USA.
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Affiliation(s)
- M D Penney
- Chemical Pathology Department, Royal Gwent Hospital, Newport, UK.
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40
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Pratt SE, Williams AW. 73-year-old woman with weakness and falls. Mayo Clin Proc 1999; 74:73-6. [PMID: 9987538 DOI: 10.4065/74.1.73] [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: 11/23/2022]
Affiliation(s)
- S E Pratt
- Mayo Graduate School of Medicine, Mayo Clinic Rochester, MN 55905, USA
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41
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Affiliation(s)
- T D DuBose
- University of Texas Medical School-Houston, Texas, USA
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42
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Kamel KS, Briceno LF, Sanchez MI, Brenes L, Yorgin P, Kooh SW, Balfe JW, Halperin ML. A new classification for renal defects in net acid excretion. Am J Kidney Dis 1997; 29:136-46. [PMID: 9002543 DOI: 10.1016/s0272-6386(97)90021-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The traditional classification of the group of disorders called renal tubular acidosis (RTA) into proximal and distal subclasses is based on which nephron segment is thought to have an abnormal function. Nevertheless, such a distinction may not be correct and also does not characterize the pathophysiology of the renal acidosis in each patient. In this article, we propose an alternative classification, one that is based on the component of net acid excretion that is abnormal. We also suggest expanding the definition of net acid excretion to include a term that describes the renal handling of metabolizable organic anions because their loss in the urine represents the loss of "potential bicarbonate." Because a low rate of excretion of ammonium (NH4+) is present in patients with both distal and isolated proximal RTA, our initial clinical step in patients with hyperchloremic metabolic acidosis (HCMA) is to evaluate the rate of excretion of NH4+. The basis for a low rate of excretion of NH4+ is shown by examining the urine pH. If the urine pH is low, further studies are performed to determine why the availability of NH3 is low; if the urine pH is high, further investigations are initiated to examine if the defect in H+ secretion involves the proximal or the distal nephron. Conversely, if the rate of excretion of NH4+ is high in a patient with HCMA, a component of the degree of acidosis could be attributable to a high rate of excretion of metabolizable organic anions. Case examples are provided to illustrate the approach and its implications for future molecular studies.
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Affiliation(s)
- K S Kamel
- Division of Nephrology, University of Toronto, Ontario, Canada
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Gemperle O, Neuweiler J, Reutter FW, Hildebrandt F, Krapf R. Familial glomerulopathy with giant fibrillar (fibronectin-positive) deposits: 15-year follow-up in a large kindred. Am J Kidney Dis 1996; 28:668-75. [PMID: 9158203 DOI: 10.1016/s0272-6386(96)90247-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A 15-year clinical follow-up is reported for a familial glomerulopathy characterized on light microscopy by the glomerular deposition of giant fibrillary deposits (Virchows Arch A Pathol Anat Histol 388:313-326, 1980). On electron microscopy, the deposits consist of randomly oriented fibrils (12 to 16 nm in width and 120 to 170 nm in length). These deposits show positive immunoreactivity for fibronectin. One hundred fifty-seven of 197 family members within five generations were investigated. The disease is characterized by the occurrence of albuminuria in the third to fourth decades of life and slow progression to end-stage renal disease over a period of 15 to 20 years with the occurrence of generalized distal tubular acidosis (renal tubular acidosis type IV), hypertension, and the nephrotic syndrome. The frequent occurrence of otherwise unexplained microalbuminuria in young individuals of generations IV and V could be indicative of incipient glomerular disease. In one affected male individual and in his unaffected sister, renal cell carcinoma was diagnosed, raising the possibility that this familial glomerulopathy might be associated with an increased risk to develop renal cell cancer by direct or indirect (associated genetic predisposition) mechanisms. The disease relapsed in one renal transplant, raising the possibility of the presence of a transferable factor that could be part of the deposited fibrillar material or, alternatively, interfere with the glomerular handling of the deposited material.
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Affiliation(s)
- O Gemperle
- Klinik B für Innere Medizin and Institute of Pathology, Kantonsspital,St Gallen, Switzerland
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Navarro JF, Quereda C, Quereda C, Gallego N, Antela A, Mora C, Ortuno J. Nephrogenic diabetes insipidus and renal tubular acidosis secondary to foscarnet therapy. Am J Kidney Dis 1996; 27:431-4. [PMID: 8604715 DOI: 10.1016/s0272-6386(96)90369-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Foscarnet is used as therapy of cytomegalovirus (CMV) infection in immunosuppressed subjects. We present a patient with human immunodeficiency virus infection under treatment with foscarnet for CMV retinitis who complained of thirst and polyuria. Laboratory data showed hypernatremia with increased plasma osmolality and metabolic hyperchloremic acidosis. A water deprivation test demonstrated a nephrogenic diabetes insipidus. Other laboratory studies, including urine pH, anion gap, titratable acidity, and bicarbonate, showed a distal tubular acidification defect. All abnormalities were transient, with recovery a few days after foscarnet withdrawal. No cases of renal acidosis, and only one case of nephrogenic diabetes insipidus, has been previously reported as a complication of foscarnet treatment. Our patient developed both nephrogenic diabetes insipidus and renal tubular acidosis with a temporal pattern that demonstrated a link between foscarnet therapy and these abnormalities.
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Affiliation(s)
- J F Navarro
- Department of Nephrology, Hospital Ramon y Cajal, Madrid, Spain
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Abstract
The practice of internal medicine involves daily exposure to abnormalities of acid-base balance. A wide variety of disease states either predispose patients to develop these conditions or lead to the use of medications that alter renal, gastrointestinal, or pulmonary function and secondarily alter acid-base balance. In addition, primary acid-base disease follows specific forms of renal tubular dysfunction (renal tubular acidosis). We review the acid-base physiologic functions of the kidney and gastrointestinal tract and the current understanding of acid-base pathophysiologic conditions. This includes a review of whole animal and renal tubular physiologic characteristics and a discussion of the current knowledge of the molecular biology of acid-base transport. We stress an approach to diagnosis that relies on knowledge of acid-base physiologic function, and we include discussion of the appropriate treatment of each disorder considered. Finally, we include a discussion of the effects of acidosis and alkalosis on human physiologic functions.
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Affiliation(s)
- M E Laski
- Texas Tech University Health Sciences Center, Section of General Internal Medicine, Lubbock, USA
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Kim GH, Han JS, Kim YS, Joo KW, Kim S, Lee JS. Evaluation of urine acidification by urine anion gap and urine osmolal gap in chronic metabolic acidosis. Am J Kidney Dis 1996; 27:42-7. [PMID: 8546137 DOI: 10.1016/s0272-6386(96)90029-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To investigate the clinical significance of urine anion gap and urine osmolal gap as indirect markers of urine acidification in chronic metabolic acidosis, we evaluated urine ammonium (NH4+), net acid excretion (NAE), urine anion gap (Na(+) + K(+) - Cl-), and urine osmolal gap (urine osmolality - [2(Na(+) + K(+)) + urea]) in 24 patients with chronic renal failure (CRF), eight patients with classic distal renal tubular acidosis (dRTA), and eight NH4Cl-loaded normal controls (NCs). Urine NH4+ excretion was lower (P < 0.001) in the CRF (5.4 +/- 0.6 mmol/d) and dRTA (19.2 +/- 2.7 mmol/d) patients than in the NCs (52.6 +/- 3.7 mmol/d); NAE was also lower (P < 0.001) in the CRF (9.8 +/- 1.6 mmol/d) and dRTA (16.7 +/- 4.7 mmol/d) patients than in the NCs (79.4 +/- 4.7 mmol/d). Urine anion gap was higher (P < 0.001) in the CRF (24.7 +/- 2.2 mmol/L) and dRTA (36.7 +/- 7.7 mmol/L) patients than in the NCs (-16.2 +/- 5.5 mmol/L). Urine osmolal gap was lower (P < 0.05) in the dRTA patients (129.7 +/- 17.0 mmol/L) than in the NCs (319.7 +/- 58.4 mmol/L). When the data from all subjects were pooled, urine anion gap correlated inversely with urine NH4+ (r = -0.70, P < 0.001) and with NAE (r = -0.83, P < 0.001), and urine osmolal gap correlated positively with urine NH4+ (r = 0.69, P < 0.01) and with NAE (r = 0.71, P < 0.05). We conclude that impaired urine acidification in CRF and dRTA patients is associated with an increase in urine anion gap and a decrease in urine osmolal gap, and that both urine anion gap and urine osmolal gap correlate well with NAE as well as with urine NH4+.
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Affiliation(s)
- G H Kim
- Department of Internal Medicine, Seoul National University, Korea
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Huizenga JR, Tangerman A, Gips CH. Determination of ammonia in biological fluids. Ann Clin Biochem 1994; 31 ( Pt 6):529-43. [PMID: 7880071 DOI: 10.1177/000456329403100602] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- J R Huizenga
- Department of Internal Medicine, University Hospital Groningen, The Netherlands
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Arruda JA, Cowell G. Distal renal tubular acidosis: molecular and clinical aspects. HOSPITAL PRACTICE (OFFICE ED.) 1994; 29:75-8, 82-8. [PMID: 8288690 DOI: 10.1080/21548331.1994.11442962] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The traditionally descriptive classification of DRTA disorders is being refined as molecular defects are identified. Diagnosis of DRTA is easy: Hyperchloremic acidosis should arouse suspicion, and confirmation can be obtained by measuring urinary pH and ammonia excretion. Treatment is also relatively straightforward and readily corrects all manifestations of the acidification defect.
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