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Bhandari R, Ekladious A, Javaid MM. Demystifying normal-anion-gap metabolic acidosis: pathophysiology, aetiology, evaluation and diagnosis. Intern Med J 2024; 54:1056-1065. [PMID: 38837536 DOI: 10.1111/imj.16418] [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: 12/17/2023] [Accepted: 05/08/2024] [Indexed: 06/07/2024]
Abstract
Normal-anion-gap metabolic acidosis (NAGMA) is a common but often under-recognised and poorly understood condition, especially by less-experienced clinicians. In adults, NAGMA might be an initial clue to a more significant underlying pathology, such as autoimmune diseases, hypergammaglobulinemia or drug toxicities. However, identifying the aetiology can be challenging due to the diverse processes involved in the development of acidosis. A better understanding of the pathophysiology of NAGMA can help treating physicians suspect and evaluate the condition early and reach the correct diagnosis. This article provides an overview of renal acid-base regulation, discusses the pathophysiological processes involved in developing NAGMA and provides a framework for evaluation to reach an accurate diagnosis.
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Affiliation(s)
- Ritesh Bhandari
- Department of General Medicine, North West Regional Hospital, Burnie, Tasmania, Australia
- Department of General Medicine, Royal Hobart Hospital, Hobart, Tasmania, Australia
| | - Adel Ekladious
- Department of General Medicine and Acute Assessment Unit, Canberra Hospital, Canberra, Australian Capital Territory, Australia
- Faculty of Health and Medical Sciences, University of Western Australia, Perth, Western Australia, Australia
| | - Muhammad M Javaid
- Monash Rural Health Mildura, Monash University, Melbourne, Victoria, Australia
- Department of Renal Medicine, Woodlands Health, Singapore
- School of Medicine, Deakin University, Melbourne, Victoria, Australia
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Wieërs MLAJ, Beynon-Cobb B, Visser WJ, Attaye I. Dietary acid load in health and disease. Pflugers Arch 2024; 476:427-443. [PMID: 38282081 PMCID: PMC11006742 DOI: 10.1007/s00424-024-02910-7] [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: 10/27/2023] [Revised: 01/07/2024] [Accepted: 01/09/2024] [Indexed: 01/30/2024]
Abstract
Maintaining an appropriate acid-base equilibrium is crucial for human health. A primary influencer of this equilibrium is diet, as foods are metabolized into non-volatile acids or bases. Dietary acid load (DAL) is a measure of the acid load derived from diet, taking into account both the potential renal acid load (PRAL) from food components like protein, potassium, phosphorus, calcium, and magnesium, and the organic acids from foods, which are metabolized to bicarbonate and thus have an alkalinizing effect. Current Western diets are characterized by a high DAL, due to large amounts of animal protein and processed foods. A chronic low-grade metabolic acidosis can occur following a Western diet and is associated with increased morbidity and mortality. Nutritional advice focusing on DAL, rather than macronutrients, is gaining rapid attention as it provides a more holistic approach to managing health. However, current evidence for the role of DAL is mainly associative, and underlying mechanisms are poorly understood. This review focusses on the role of DAL in multiple conditions such as obesity, cardiovascular health, impaired kidney function, and cancer.
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Affiliation(s)
- Michiel L A J Wieërs
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Beverley Beynon-Cobb
- Department of Nutrition & Dietetics, University Hospitals Coventry & Warwickshire NHS Trust, Coventry, UK
- Department of Twin Research and Genetic Epidemiology, King's College London, London, UK
| | - Wesley J Visser
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
- Department of Internal Medicine, Division of Dietetics, Erasmus MC, University Medical Center, Rotterdam, The Netherlands
| | - Ilias Attaye
- Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
- Department of Twin Research and Genetic Epidemiology, King's College London, London, UK.
- Amsterdam Cardiovascular Sciences, Diabetes & Metabolism, Amsterdam, The Netherlands.
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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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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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Smeulders N, Cho A, Alshaiban A, Read K, Fagan A, Easty M, Minhas K, Barnacle A, Hayes W, Bockenhauer D. Shockwaves and the Rolling Stones: An Overview of Pediatric Stone Disease. Kidney Int Rep 2023; 8:215-228. [PMID: 36815103 PMCID: PMC9939363 DOI: 10.1016/j.ekir.2022.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/14/2022] [Accepted: 11/21/2022] [Indexed: 12/03/2022] Open
Abstract
Urinary stone disease is a common problem in adults, with an estimated 10% to 20% lifetime risk of developing a stone and an annual incidence of almost 1%. In contrast, in children, even though the incidence appears to be increasing, urinary tract stones are a rare problem, with an estimated incidence of approximately 5 to 36 per 100,000 children. Consequently, typical complications of rare diseases, such as delayed diagnosis, lack of awareness, and specialist knowledge, as well as difficulties accessing specific treatments also affect children with stone disease. Indeed, because stone disease is such a common problem in adults, frequently, it is adult practitioners who will first be asked to manage affected children. Yet, there are unique aspects to pediatric urolithiasis such that treatment practices common in adults cannot necessarily be transferred to children. Here, we review the epidemiology, etiology, presentation, investigation, and management of pediatric stone disease; we highlight those aspects that separate its management from that in adults and make a case for a specialized, multidisciplinary approach to pediatric stone disease.
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Affiliation(s)
- Naima Smeulders
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
| | - Alexander Cho
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
| | - Abdulelah Alshaiban
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
- Department of Pediatrics, College of Medicine, King Saud University, King Saud University Medical City, Riyadh, Saudi Arabia
| | - Katharine Read
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
| | - Aisling Fagan
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
| | - Marina Easty
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
| | - Kishore Minhas
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
| | - Alex Barnacle
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
| | - Wesley Hayes
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
| | - Detlef Bockenhauer
- Great Ormond Street Hospital National Health Service Foundation Trust, London, UK
- Department of Renal Medicine, University College London, London, UK
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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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