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Pflugers Archiv : European Journal of... Apr 2024The disposal of ammonia, the main proton buffer in the urine, is important for acid-base homeostasis. Renal ammonia excretion is the predominant contributor to renal net... (Review)
Review
The disposal of ammonia, the main proton buffer in the urine, is important for acid-base homeostasis. Renal ammonia excretion is the predominant contributor to renal net acid excretion, both under basal condition and in response to acidosis. New insights into the mechanisms of renal ammonia production and transport have been gained in the past decades. Ammonia is the only urinary solute known to be produced in the kidney and selectively transported through the different parts of the nephron. Both molecular forms of total ammonia, NH and NH, are transported by specific proteins. Proximal tubular ammoniagenesis and the activity of these transport processes determine the eventual fate of total ammonia produced and excreted by the kidney. In this review, we summarized the state of the art of ammonia handling by the kidney and highlighted the newest processes described in the last decade.
Topics: Humans; Ammonia; Acid-Base Equilibrium; Kidney; Homeostasis; Acidosis
PubMed: 38448728
DOI: 10.1007/s00424-024-02940-1 -
Internal Medicine Journal Jun 2024Normal-anion-gap metabolic acidosis (NAGMA) is a common but often under-recognised and poorly understood condition, especially by less-experienced clinicians. In adults,... (Review)
Review
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.
PubMed: 38837536
DOI: 10.1111/imj.16418 -
La Tunisie Medicale 2023Distal renal tubular acidosis (dRTA) is a rare genetic disorder due to the incapacity of the α intercalated cells to excrete protons in the collecting duct. This...
INTRODUCTION
Distal renal tubular acidosis (dRTA) is a rare genetic disorder due to the incapacity of the α intercalated cells to excrete protons in the collecting duct. This impaired distal acidification of urine leads to a chronic hyperchloremic metabolic acidosis with a normal plasma anion gap, hypokalemia, and hypercalciuria with hypocitraturia causing nephrocalcinosis. Primary dRTA is inherited either as an autosomal dominant (SLC1A4 gene) or autosomal recessive trait (ATP6V0A1/ATP6V1B1 genes).
AIM
To analyze the genotype-phenotype correlation of dTA in Tunisia.
METHODS
In this study we present all available data of patients followed in our center for dRTA over the last 28 years and who had a genetic study. This was a retrospective descriptive study from January 1991 to December 2018, conducted in the Pediatrics Department of the Charles Nicolle Hospital in Tunis.
RESULTS
Twenty-five cases of dRTA were collected and were offered genetic analysis to confirm the diagnosis. The molecular mutation was confirmed in 13 patients of whom 11 had homozygous mutations in ATP6V1B1(G1) and 2 had homozygous mutations in ATP6V0A4(G2). Median age of diagnosis was 8.9 months. Severe growth retardation was documented in nine children with mutations in ATP6V1B1, in eight children with no genetic mutation and in the two patients with a mutation in ATP6V0A4. All children were found to have metabolic acidosis at initial presentation. Hypokalemia was found in 19 children. All patients were polyuric. Twenty-two patients had nephrocalcinosis (88%). The treatment was based on alkali prescription and substitution of potassium chloride. Sensorineural hearing loss (SNHL) was documented in 12 children. At the last consultation, 14 patients had chronic kidney disease (CKD) stage 2 or higher, 8 of whom were in the group with negative genetic analysis.
CONCLUSION
According to the early onset in patients, the recessive mode seems to be the mode of transmission in Tunisia. dRTA was long considered to not affect renal function, but we note a decline in eDFG.
Topics: Child; Humans; Infant; Acidosis, Renal Tubular; Tunisia; Hypokalemia; Nephrocalcinosis; Retrospective Studies; Genetic Association Studies; Vacuolar Proton-Translocating ATPases; Organometallic Compounds
PubMed: 38445406
DOI: No ID Found -
Internal Medicine (Tokyo, Japan) Dec 2023An 80-year-old man presented with electrolyte abnormalities, particularly hypocalcemia (3.6 mg/dL). He was diagnosed with bone and lymph node metastases from prostate...
Proximal Renal Tubular Acidosis Complicated by Severe Hypocalcemia Caused by Malnutrition and Inappropriate Long-term Use of Zoledronate: A Case Report and Review of the Literature.
An 80-year-old man presented with electrolyte abnormalities, particularly hypocalcemia (3.6 mg/dL). He was diagnosed with bone and lymph node metastases from prostate cancer seven years earlier and continuously received goserelin, bicalutamide, and zoledronate. He later developed gradually worsening hypocalcemia, hypokalemia, hypophosphatemia, hypouricemia, renal dysfunction, and weight loss. Urinary potassium and phosphate loss, renal glucosuria, metabolic acidosis, and a low urine pH (5.0) were observed. Given the acquired onset and clinical course, we diagnosed the patient with zoledronate-induced proximal renal tubular acidosis. In the present case, severe hypocalcemia may have been caused by malnutrition and inappropriate long-term use of zoledronate.
PubMed: 38044157
DOI: 10.2169/internalmedicine.1753-23 -
Journal of the Neurological Sciences Sep 2023Electrolyte disorders are among the important conditions negatively affecting the disease course of neuromyelitis optica spectrum disorder (NMOSD). Possible mechanisms...
OBJECTIVE
Electrolyte disorders are among the important conditions negatively affecting the disease course of neuromyelitis optica spectrum disorder (NMOSD). Possible mechanisms may include renal tubular acidosis (RTA) accompanying Sjögren's syndrome (SS), syndrome of inappropriate antidiuretic hormone secretion (SIADH), and central diabetes insipidus (DI). Currently, the overlap profiles between these conditions remain uncertain.
METHODS
This cross-sectional study collected data from the nationwide administrative Diagnosis Procedure Combination (DPC) database and evaluated the overlap profiles.
RESULTS
Among the 28,285,908 individuals from 1203 DPC-covered hospitals, 8477 had NMOSD, 174108 had SS, 4977 had RTA, 7640 had SIADH, and 24,789 had central DI. Of those with NMOSD, 986 (12%) had SS. The odds ratio (OR) for a diagnosis of NMOSD in those with SS compared with those without was 21 [95% confidence interval (CI), 20-23]. Overlap between NMOSD and SS was seen both in males (OR, 28 [95% CI, 23-33]) and females (OR, 16 [15-17]) and was more prominent in the younger population. Among patients with SS, the prevalence of RTA was lower in patients with NMOSD compared with those without NMOSD. Patients with NMOSD showed a higher prevalence of SIADH (OR, 11 [7.5-17]; p < 0.0001) and DI (OR, 3.7 [2.4-5.3]; p < 0.0001). Comorbid SS in NMOSD was associated with a higher prevalence of DI.
CONCLUSIONS
Patients with NMOSD are likely to have SS, SIADH, and central DI. RTA in SS does not facilitate the overlap between NMOSD and SS. SS in NMOSD may predispose patients to DI.
Topics: Male; Female; Humans; Sjogren's Syndrome; Neuromyelitis Optica; Inappropriate ADH Syndrome; Cross-Sectional Studies; Electrolytes; Aquaporin 4
PubMed: 37515845
DOI: 10.1016/j.jns.2023.120742 -
Biochemical Genetics Nov 2023SLC4A4 variants are the etiologies of inherited proximal renal tubular acidosis (pRTA), which results in metabolic acidosis, hypokalemia, glaucoma, band keratopathy, and...
SLC4A4 variants are the etiologies of inherited proximal renal tubular acidosis (pRTA), which results in metabolic acidosis, hypokalemia, glaucoma, band keratopathy, and cataract. This study aims to characterize SLC4A4 variant and uniparental isodisomy of chromosome 4 in a patient, and analyse the functional characterization of SLC4A4 variants. This study analyzed renal tubular acidosis disease genes by whole exome sequencing (WES). H3M2 algorithm was used to analyze the run of homozygosity region in chromosomal regions in trio-WES data. The pathogenicity analysis of variants was performed using bioinformatics tools. Additionally, protein stability was analyzed by cycloheximide chase assay. Whole-cell patch clamping was used to examine the electrophysiological properties of NBCe1-A. A novel homozygous SLC4A4 variant was identified in the patient: a missense variant c.496C > T, p. Arg166Trp (NM_003759.4). But the father was heterozygous variant carrier, and the mother did not detect the variant. The H3M2 and UPDio algorithm revealed paternal uniparental isodisomy on chromosome 4 in the patient. SIFT, Poly Phen-2, FATHMM and Mutant Taster showed that the variant might be pathogenic. The tertiary structure analysis showed that the variant could cause structural damage to NBCe1 protein. Foldx results showed that the protein stability of the variant was slightly reduced. Cycloheximide chase assay demonstrated that the variant affects protein stability. The result of electrophysiological studies showed that the variant altered Na/HCO cotransport activity of protein. In conclusion, the study is the first to report a pRTA patient with Arg166Trp variant with UPiD (4) pat and analyze the function of Arg166Trp variant.
PubMed: 37952039
DOI: 10.1007/s10528-023-10554-y -
Journal of Medical Case Reports Sep 2023Metformin-induced lactic acidosis with acute kidney injury is rare but well known. Here we report a case of a Japanese patient taking metformin who experienced severe...
BACKGROUND
Metformin-induced lactic acidosis with acute kidney injury is rare but well known. Here we report a case of a Japanese patient taking metformin who experienced severe acute renal failure accompanied with significantly elevated metformin plasma concentrations and signs of lactic acidosis.
CASE PRESENTATION
A 60-year-old Japanese man with type II diabetes, who was taking metformin (500 mg three times a day) along with several other medications, visited the emergency department with dizziness, malaise, and oliguria. The initial laboratory test results showed elevated levels of serum creatinine and blood urea nitrogen, although his renal function was normal approximately 2 weeks earlier. His lactate level was raised (4.27 mmol/L), and he was diagnosed with lactic acidosis. Considering the low creatinine clearance and elevated urinary albumin/serum creatinine ratio, urinary N-acetyl-β-D-glucosaminidase level, and β2-microglobulin level, the patient was further diagnosed with AKI (in other words, acute tubular necrosis). A renal biopsy performed on day 3 after admission revealed renal tubular epithelium necrosis, supporting this diagnosis. The patient underwent intermittent hemodialysis until he was discharged on day 13. The metformin concentrations on days 3, 5, and 7 were 8.95, 2.58, and 0.16 μg/mL, respectively, which is significantly higher than the maximal steady-state concentration of metformin at the recommended dosage (approximately 1 μg/mL). The calculated pharmacokinetic parameters of metformin suggested poor renal excretion and a low distribution volume at higher metformin levels. Other possible acute kidney injury-causing factors included dehydration, alcohol consumption, and the use of an angiotensin receptor blocker or SGLT2 inhibitor.
CONCLUSIONS
This is the first reported case of acute kidney injury possibly caused by high levels of metformin with lactic acidosis in a patient treated with the recommended metformin dose. Thus, the development of metformin-induced acute kidney injury should be considered for patients with several acute kidney injury risk factors who are taking metformin.
Topics: Male; Humans; Middle Aged; Metformin; Diabetes Mellitus, Type 2; Acidosis, Lactic; Creatinine; Acute Kidney Injury; Kidney Tubular Necrosis, Acute; Necrosis
PubMed: 37715272
DOI: 10.1186/s13256-023-04136-0 -
Pflugers Archiv : European Journal of... Apr 2024Metabolic acidosis is a frequent complication in non-transplant chronic kidney disease (CKD) and after kidney transplantation. It occurs when net endogenous acid... (Review)
Review
Metabolic acidosis is a frequent complication in non-transplant chronic kidney disease (CKD) and after kidney transplantation. It occurs when net endogenous acid production exceeds net acid excretion. While nephron loss with reduced ammoniagenesis is the main cause of acid retention in non-transplant CKD patients, additional pathophysiological mechanisms are likely inflicted in kidney transplant recipients. Functional tubular damage by calcineurin inhibitors seems to play a key role causing renal tubular acidosis. Notably, experimental and clinical studies over the past decades have provided evidence that metabolic acidosis may not only be a consequence of CKD but also a driver of disease. In metabolic acidosis, activation of hormonal systems and the complement system resulting in fibrosis have been described. Further studies of changes in renal metabolism will likely contribute to a deeper understanding of the pathophysiology of metabolic acidosis in CKD. While alkali supplementation in case of reduced serum bicarbonate < 22 mmol/l has been endorsed by CKD guidelines for many years to slow renal functional decline, among other considerations, beneficial effects and thresholds for treatment have lately been under intense debate. This review article discusses this topic in light of the most recent results of trials assessing the efficacy of dietary and pharmacological interventions in CKD and kidney transplant patients.
Topics: Humans; Renal Insufficiency, Chronic; Acidosis; Kidney; Acidosis, Renal Tubular; Diet
PubMed: 38279993
DOI: 10.1007/s00424-024-02912-5 -
Nephron 2024Familial hyperkalemic hypertension (FHHt) is an inherited disease characterized by hyperkalemia, hypertension, and hyperchloremic acidosis (HCA). The primary defect is a...
INTRODUCTION
Familial hyperkalemic hypertension (FHHt) is an inherited disease characterized by hyperkalemia, hypertension, and hyperchloremic acidosis (HCA). The primary defect is a hyperactive sodium chloride co-transporter, expressed in the renal distal tubule. FHHt is caused by mutation in either WNK1, WNK4, KLHL3, or Cul3. The mechanism of HCA is not completely understood.
METHODS
Clinical and genetic data were collected from the largest family with FHHt described in the literature. Urine ammonia was measured in 26 family members. Epilepsy was diagnosed clinically.
RESULTS
Of the 85 family members, 44 are affected by the Q565E WNK4 mutation, and 28 are newly described. In genetically engineered mice, urinary ammonium was decreased. In our study, urine ammonium did not change. In 11 unaffected subjects, urine ammonia per creatinine was 8.013 ± 3.620 m
m /mm, and in 15 subjects affected by FHHt, it was 8.990 ± 4.300 mm /mm (p = 0.546, not significant). Due to the large family size and prolonged follow-up, rare conditions can be identified. Indeed, two children have genetic generalized epilepsy and one child has migraine. The prevalence of epilepsy is 4.545% (2/44) much higher than in the general population (0.681%). This difference is statistically significant (χ2 with Yates correction = 5.127, p = 0.023).CONCLUSIONS
We provide further evidence that the origin of HCA in FHHt lies in the proximal renal tubule. The association of FHHt with epilepsy leads us to speculate that the raised serum K in susceptible subjects may cause a rise in CSF K, and extracellular cerebral K, leading to epilepsy.
Topics: Child; Mice; Animals; Humans; Hyperkalemia; Acidosis, Renal Tubular; Ammonia; Protein Serine-Threonine Kinases; Hypertension; Pseudohypoaldosteronism; Epilepsy; Seizures; Ammonium Compounds
PubMed: 37666233
DOI: 10.1159/000531868 -
Zhong Nan Da Xue Xue Bao. Yi Xue Ban =... Feb 2024Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease that is prevalent in middle-aged and elderly women, characterized by dry mouth, dry eyes, fatigue, and... (Review)
Review
Primary Sjögren's syndrome (pSS) is a systemic autoimmune disease that is prevalent in middle-aged and elderly women, characterized by dry mouth, dry eyes, fatigue, and joint pain. Nearly one-third pSS patients have been suffering with osteoporosis (OP), displaying symptoms of lumbago, back pain, and even fracture, all of which severely affect their life quality. Common risk factors for pSS and OP include gender and age, persistent state of inflammation, immune disorders, intestinal flora imbalance, vitamin D deficiency, dyslipidemia and sarcopenia. Meanwhile, the comorbidities of pSS, such as renal tubular acidosis, primary biliary cholangitis, autoimmune thyroid diseases, and drugs (glucocorticoids, methotrexate, and cyclophosphamide) are unique risk factors for pSS complicated with OP. Education, guidance of healthy lifestyle, and OP screening are recommended for bone management of pSS patients. Early detection and intervention are crucial for keeping bone health and life quality in pSS patients.
Topics: Humans; Sjogren's Syndrome; Osteoporosis; Risk Factors; Female; Comorbidity; Vitamin D Deficiency; Quality of Life
PubMed: 38755728
DOI: 10.11817/j.issn.1672-7347.2024.230295