-
La Revue Du Praticien Oct 1990Normal adults with normal protein intakes have a urinary NH4 excretion of 40 to 50 mmol/24 hours and a variable urinary pH. In cases of metabolic acidosis a urinary pH...
Normal adults with normal protein intakes have a urinary NH4 excretion of 40 to 50 mmol/24 hours and a variable urinary pH. In cases of metabolic acidosis a urinary pH less than 5.5 suggests an extra-renal origin whilst a urinary pH greater than 5.5 is in favour of renal acidosis, but there are many exceptions to this rule. On the other hand, urinary NH4 excretion is always greater than 70 mmol/24 hours in the first case and less than 40-50 mmol/24 hours in the second; and the use of the urinary anionic gap (Na + K - Cl), negative in the first case and positive in the second, enables the two situations to be distinguished. The acidosis of nephron reduction is easily recognised in cases of severe renal failure with an increase in unmeasured plasma anions whilst tubular acidoses are accompanied by a hyperchloremia. Measurement of fractional HCO3 excretion after an oral loading dose of NaHCO3, preferably by TmCHO3 with respect to GFR, distinguishes proximal tubular acidosis (low TmHCO3) from distal tubular acidosis (normal or high TmHCO3). In the latter case, the presence of hypokalemia suggests a distal tubular acidosis either due to deficiency of the H(+)-ATPase pumps (absence of increased urinary pCO2 after oral loading dose of NaHCO3) or to the inability of the kidney to maintain a normal H+ gradient (normal increase of urinary pCO2. The presence of hyperkalemia suggests diseases associated with hypoaldosteronism (low or inappropriate serum aldosterone concentrations), abnormal transepithelial voltages or with a pseudo-hypoaldosteronism syndrome (high plasma aldosterone concentration). The prevalence of distal tubular acidosis with hyperkalemia is on the increase whilst tubular acidosis with hypokalemia remains rare.
Topics: Acid-Base Equilibrium; Acidosis, Renal Tubular; Adult; Humans; Hyperkalemia; Hypokalemia
PubMed: 2237203
DOI: No ID Found -
The Veterinary Clinics of North... Dec 2007Renal tubular disorders have been sporadically reported in horses. Only three types of tubular defects have been recognized: (1) nephrogenic diabetes insipidus,... (Review)
Review
Renal tubular disorders have been sporadically reported in horses. Only three types of tubular defects have been recognized: (1) nephrogenic diabetes insipidus, attributable to unresponsiveness of the renal tubules to antidiuretic hormone; (2) distal renal tubular acidosis (RTA; type I); and (3) proximal RTA (type II). The following review focuses on RTA and nephrogenic diabetes insipidus.
Topics: Acid-Base Equilibrium; Acidosis, Renal Tubular; Animals; Diagnosis, Differential; Horse Diseases; Horses; Kidney Function Tests; Kidney Tubules, Distal; Kidney Tubules, Proximal; Prognosis; Risk Factors
PubMed: 18061854
DOI: 10.1016/j.cveq.2007.09.005 -
Journal of Veterinary Internal Medicine 2001Renal tubular acidosis (RTA) is characterized by altered renal tubular function resulting in hyperchloremic metabolic acidosis. The purpose of the study was to describe...
Renal tubular acidosis (RTA) is characterized by altered renal tubular function resulting in hyperchloremic metabolic acidosis. The purpose of the study was to describe RTA in 16 horses. No breed or sex predilection was found. The mean age at onset of the disease was 7 years of age. The type of diet had no apparent effect on development of RTA. The most common clinical signs were depression, poor performance, weight loss, and anorexia. Initial blood work revealed a marked hyperchloremic metabolic acidosis in all horses and a compensatory respiratory response in most horses. Sixty-three percent (10/16) of the horses had some evidence of renal damage or disease. Initial treatment consisted of large amounts of sodium bicarbonate given intravenously and orally for the prompt correction of the acidosis. Response to treatment was largely dependent on the rate of sodium bicarbonate administration. Long-term oral supplementation with NaHCO3 was required for the maintenance of normal acid-base status in individual horses. Recurrence of RTA was noted in 56% (9/16) of the horses. Horses with evidence of renal disease had multiple relapses. RTA should be considered as a differential diagnosis in horses with vague signs of depression, weight loss, and anorexia. The pathogenesis of RTA in horses remains uncertain, but prompt recognition and early aggressive intravenous sodium bicarbonate therapy followed by long-term oral supplementation seem to be important to successful management.
Topics: Acidosis, Renal Tubular; Animals; California; Female; Horse Diseases; Horses; Male; Michigan; Sodium Bicarbonate
PubMed: 11300597
DOI: 10.1892/0891-6640(2001)015<0136:rtaih>2.3.co;2 -
Kidney International Mar 2020Distal renal tubular acidosis is a rare renal tubular disorder characterized by hyperchloremic metabolic acidosis and impaired urinary acidification. Mutations in three...
Distal renal tubular acidosis is a rare renal tubular disorder characterized by hyperchloremic metabolic acidosis and impaired urinary acidification. Mutations in three genes (ATP6V0A4, ATP6V1B1 and SLC4A1) constitute a monogenic causation in 58-70% of familial cases of distal renal tubular acidosis. Recently, mutations in FOXI1 have been identified as an additional cause. Therefore, we hypothesized that further monogenic causes of distal renal tubular acidosis remain to be discovered. Panel sequencing and/or whole exome sequencing was performed in a cohort of 17 families with 19 affected individuals with pediatric onset distal renal tubular acidosis. A causative mutation was detected in one of the three "classical" known distal renal tubular acidosis genes in 10 of 17 families. The seven unsolved families were then subjected to candidate whole exome sequencing analysis. Potential disease causing mutations in three genes were detected: ATP6V1C2, which encodes another kidney specific subunit of the V-type proton ATPase (1 family); WDR72 (2 families), previously implicated in V-ATPase trafficking in cells; and SLC4A2 (1 family), a paralog of the known distal renal tubular acidosis gene SLC4A1. Two of these mutations were assessed for deleteriousness through functional studies. Yeast growth assays for ATP6V1C2 revealed loss-of-function for the patient mutation, strongly supporting ATP6V1C2 as a novel distal renal tubular acidosis gene. Thus, we provided a molecular diagnosis in a known distal renal tubular acidosis gene in 10 of 17 families (59%) with this disease, identified mutations in ATP6V1C2 as a novel human candidate gene, and provided further evidence for phenotypic expansion in WDR72 mutations from amelogenesis imperfecta to distal renal tubular acidosis.
Topics: Acidosis, Renal Tubular; Anion Exchange Protein 1, Erythrocyte; Child; Chloride-Bicarbonate Antiporters; DNA Mutational Analysis; Forkhead Transcription Factors; Humans; Mutation; Vacuolar Proton-Translocating ATPases; Exome Sequencing
PubMed: 31959358
DOI: 10.1016/j.kint.2019.09.026 -
Nephrologie 1985Type IV renal tubular acidosis (RTA) is a syndrome of tubular dysfunction manifested clinically by persisting hyperkalemia and metabolic acidosis that occurs usually in... (Review)
Review
Type IV renal tubular acidosis (RTA) is a syndrome of tubular dysfunction manifested clinically by persisting hyperkalemia and metabolic acidosis that occurs usually in patients with mild to moderate chronic glomerular insufficiency. The pathophysiologic characteristics include: reduced renal clearance of potassium; a reduced rate of renal bicarbonate reabsorption at normal plasma bicarbonate concentrations (the magnitude of which is insufficiently great to implicate the proximal tubule); an unimpaired ability to maintain a steep hydrogen ion concentration gradient between blood and urine during acidosis; and a reduced rate of renal net acid excretion despite highly acidic urine, due in part to reduced urinary excretion of ammonium, which in turn appears to be due in part to suppression of renal ammoniagenesis by hyperkalemia. Many patients with type IV RTA, but not all, have hyporeninemic hypoaldosteronism. The roles of mineralocorticoid deficiency and hyperkalemia in the pathogenesis of type IV RTA will be considered and the ameliorative effects of treatment with fludrocortisone, furosemide, and dietary potassium restriction reviewed.
Topics: Acidosis, Renal Tubular; Aldosterone; Diet; Fludrocortisone; Humans; Hyperkalemia; Potassium
PubMed: 3908957
DOI: No ID Found -
Annual Review of Medicine 1986Renal tubular acidosis (RTA) is associated with a large group of disorders that interfere with normal tubular hydrogen-ion handling by any of several mechanisms. This... (Review)
Review
Renal tubular acidosis (RTA) is associated with a large group of disorders that interfere with normal tubular hydrogen-ion handling by any of several mechanisms. This review presents an approach to the pathophysiology, diagnosis, and therapy of RTA by defining three major subgroups: proximal RTA, distal RTA presenting with normal or decreased serum potassium (hypokalemic distal RTA), and distal RTA presenting with increased serum potassium (hyperkalemic distal RTA).
Topics: Acidosis, Renal Tubular; Adult; Aldosterone; Ammonium Chloride; Animals; Bicarbonates; Bone Diseases, Metabolic; Child; Diagnosis, Differential; Fludrocortisone; Humans; Hyperkalemia; Hyperparathyroidism, Secondary; Hypocalcemia; Hypokalemia; Kidney Calculi; Kidney Tubules, Distal; Kidney Tubules, Proximal; Nephrocalcinosis
PubMed: 3518609
DOI: 10.1146/annurev.me.37.020186.001535 -
Nihon Rinsho. Japanese Journal of... Sep 1992Renal tubular acidosis (RTA) can be separated into three main types: distal RTA (the defect in the excretion of hydrogen ion), proximal RTA (the defect in the... (Review)
Review
Renal tubular acidosis (RTA) can be separated into three main types: distal RTA (the defect in the excretion of hydrogen ion), proximal RTA (the defect in the reabsorption of bicarbonate), and hyperkalemic RTA. Some patients present combined types of proximal and distal RTA. Most of the pediatric patients with RTA manifest failure to thrive. They have hyperchloremic metabolic acidosis and normal plasma anion gap. Fractional excretion of bicarbonate is below 5% in dRTA and over 15% in pRTA. Renal complications of dRTA are nephrocalcinosis, renal calculi, renal cysts and reversible low molecular weight proteinuria. The patient with isolated pRTA is very rare.
Topics: Acidosis, Renal Tubular; Humans
PubMed: 1434012
DOI: No ID Found -
Clinical Science (London, England :... Dec 19951. Metabolic acidosis invariably accompanies chronic renal failure, and short periods of metabolic acidosis cause renal growth and proteinuria in normal rats. Rates of...
1. Metabolic acidosis invariably accompanies chronic renal failure, and short periods of metabolic acidosis cause renal growth and proteinuria in normal rats. Rates of ammoniagenesis are increased in chronic renal failure, and it has been suggested that this contributes to disease progression. This study assessed (i) whether prolonged acidosis causes chronic renal injury in the normal kidney and (ii) whether abrogation of acidosis slows disease progression in the remnant kidney. 2. Metabolic acidosis was induced in normal rats by dietary hydrochloric acid. Urinary excretion of total protein, lysozyme and albumin increased, peaking at week 8 but returning to baseline by week 14. At killing after 14 weeks, kidney weights, glomerular filtration rates and serum creatinine were the same in both groups, but kidney/body weight and kidney/heart weight ratios were greater in the acidotic group. All kidneys were normal by light microscopy. 3. Rats subjected to five-sixths nephrectomy were given sufficient dietary bicarbonate to abolish uraemic acidosis, and their outcome was compared with that of non-alkalinized remnants (controls). Proteinuria, glomerular filtration rates, blood pressure, histological injury and time to the development of terminal uraemia were no better in bicarbonate-supplemented animals than in controls. 4. These data demonstrate that metabolic acidosis neither causes nor exacerbates chronic renal injury. We conclude that the treatment of uraemic acidosis is unlikely to influence disease progression in patients with chronic renal failure.
Topics: Acidosis, Renal Tubular; Animals; Female; Kidney Failure, Chronic; Rats; Rats, Wistar
PubMed: 8549084
DOI: 10.1042/cs0890643 -
Critical Care (London, England) 2005The Canadian physiologist PA Stewart advanced the theory that the proton concentration, and hence pH, in any compartment is dependent on the charges of fully ionized and... (Review)
Review
The Canadian physiologist PA Stewart advanced the theory that the proton concentration, and hence pH, in any compartment is dependent on the charges of fully ionized and partly ionized species, and on the prevailing CO2 tension, all of which he dubbed independent variables. Because the kidneys regulate the concentrations of the most important fully ionized species ([K+], [Na+], and [Cl-]) but neither CO2 nor weak acids, the implication is that it should be possible to ascertain the renal contribution to acid-base homeostasis based on the excretion of these ions. One further corollary of Stewart's theory is that, because pH is solely dependent on the named independent variables, transport of protons to and from a compartment by itself will not influence pH. This is apparently in great contrast to models of proton pumps and bicarbonate transporters currently being examined in great molecular detail. Failure of these pumps and cotransporters is at the root of disorders called renal tubular acidoses. The unquestionable relation between malfunction of proton transporters and renal tubular acidosis represents a problem for Stewart theory. This review shows that the dilemma for Stewart theory is only apparent because transport of acid-base equivalents is accompanied by electrolytes. We suggest that Stewart theory may lead to new questions that must be investigated experimentally. Also, recent evidence from physiology that pH may not regulate acid-base transport is in accordance with the concepts presented by Stewart.
Topics: Acid-Base Equilibrium; Acidosis, Renal Tubular; Chemistry, Clinical; Humans
PubMed: 16356241
DOI: 10.1186/cc3802 -
Clinical Journal of the American... Feb 2015Intercalated cells are kidney tubule epithelial cells with important roles in the regulation of acid-base homeostasis. However, in recent years the understanding of the... (Review)
Review
Intercalated cells are kidney tubule epithelial cells with important roles in the regulation of acid-base homeostasis. However, in recent years the understanding of the function of the intercalated cell has become greatly enhanced and has shaped a new model for how the distal segments of the kidney tubule integrate salt and water reabsorption, potassium homeostasis, and acid-base status. These cells appear in the late distal convoluted tubule or in the connecting segment, depending on the species. They are most abundant in the collecting duct, where they can be detected all the way from the cortex to the initial part of the inner medulla. Intercalated cells are interspersed among the more numerous segment-specific principal cells. There are three types of intercalated cells, each having distinct structures and expressing different ensembles of transport proteins that translate into very different functions in the processing of the urine. This review includes recent findings on how intercalated cells regulate their intracellular milieu and contribute to acid-base regulation and sodium, chloride, and potassium homeostasis, thus highlighting their potential role as targets for the treatment of hypertension. Their novel regulation by paracrine signals in the collecting duct is also discussed. Finally, this article addresses their role as part of the innate immune system of the kidney tubule.
Topics: Acid-Base Equilibrium; Acidosis, Renal Tubular; Animals; Cell Differentiation; Cell Lineage; Epithelial Cells; Humans; Immunity, Innate; Kidney Tubules, Collecting; Phenotype; Renin-Angiotensin System
PubMed: 25632105
DOI: 10.2215/CJN.08880914