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Archives de Pediatrie : Organe Officiel... Jun 2010
Topics: Acidosis, Renal Tubular; Bicarbonates; Child; Diagnosis, Differential; Humans; Hypoaldosteronism; Infant; Kidney Function Tests; Kidney Tubules, Distal; Kidney Tubules, Proximal; Protons
PubMed: 20654836
DOI: 10.1016/S0929-693X(10)70054-3 -
Archivos Espanoles de Urologia Jan 2021Renal tubular acidosis (RTA) is a set of raredis orders in which the renal tubule is unable to excreteacid normally and there by maintain normal acid-basebalance,...
Renal tubular acidosis (RTA) is a set of raredis orders in which the renal tubule is unable to excreteacid normally and there by maintain normal acid-basebalance, resulting in a complete or incomplete metabolicacidosis. In distal RTA (dRTA, also known as classicalor type 1 RTA), there is a defect in excreting H+ ionsalong the distal nephron (distal tubule and collectingduct), leading to an alkaline urinary pH with calcium phosphate precipitation and stones. Causes of dRTAinclude genetic mutations, autoimmune disease, and some drugs.Clinical manifestations of the genetic forms of dRTA typically occur during childhood and may vary from mildclinical symptoms, such as a mild metabolic acidosis, hypokalaemia,and incidental detection of kidney stones, to more serious manifestations such as failure to thrive,severe metabolic acidosis, rickets and nephrocalcinosis.Progressive hearing loss may develop in patients withrecessive dRTA, which, depending the causative genemutation, can be present at birth or develop later in adolescence or early adulthood. Diagnosis of dRTA can be challenging, since it requires a high index of suspicion and/or measurement of urinary pH after an acid load, usually in the form of oral ammonium chloride; this should normally acidify the urine to pH below 5.3. In dRTA, urinary citrate levels a real so low and patients are at increased risk of for mingkidney stones from a combination of alkaline urine and low citrate. Ideally, affected patients need regular outpatient follow-up by a urologist and nephrologist. Thus, any patient found to have a calcium phosphate kidney stone, low urinary citrate, and raised urinary pH, especially with an early morning pH >5.5, should be evaluated for underlying dRTA. Patients with complete dRTA will have a low (<20 mmol/L) plasma or serum bicarbonate concentration, whereas in those with incomplete dRTA, bicarbonate levels are usually normal. Oral alkali as potassiumcitrate is still the mainstay of treatment in dRTA.
Topics: Acidosis, Renal Tubular; Adolescent; Adult; Ammonium Chloride; Child; Citric Acid; Humans; Hydrogen-Ion Concentration; Kidney Calculi
PubMed: 33459628
DOI: No ID Found -
The International Journal of... Jun 2005Renal tubular acidosis is a metabolic acidosis due to impaired acid excretion by the kidney. Hyperchloraemic acidosis with a normal anion gap and normal (or near normal)... (Review)
Review
Renal tubular acidosis is a metabolic acidosis due to impaired acid excretion by the kidney. Hyperchloraemic acidosis with a normal anion gap and normal (or near normal) glomerular filtration rate, and in the absence of diarrhoea, defines this disorder. However, systemic acidosis is not always evident and renal tubular acidosis can present with hypokalaemia, medullary nephrocalcinosis and recurrent calcium phosphate stone disease, as well as growth retardation and rickets in children, or short stature and osteomalacia in adults. Renal dysfunction in renal tubular acidosis is not always confined to acid excretion and can be part of a more generalised renal tubule defect, as in the renal Fanconi syndrome. Isolated renal tubular acidosis is more usually acquired, due to drugs, autoimmune disease, post-obstructive uropathy or any cause of medullary nephrocalcinosis. Less commonly, it is inherited and may be associated with deafness, osteopetrosis or ocular abnormalities. The clinical classification of renal tubular acidosis has been correlated with our current physiological model of how the nephron excretes acid, and this has facilitated genetic studies that have identified mutations in several genes encoding acid and base ion transporters. In vitro functional studies of these mutant proteins in cell expression systems have helped to elucidate the molecular mechanisms underlying renal tubular acidosis, which ultimately may lead to new therapeutic options in what is still treatment only by giving an oral alkali.
Topics: Acidosis, Renal Tubular; Adult; Animals; Anion Exchange Protein 1, Erythrocyte; Carbonic Anhydrase II; Child; Humans; Kidney; Proton-Translocating ATPases
PubMed: 15778079
DOI: 10.1016/j.biocel.2005.01.002 -
Current Opinion in Nephrology and... Mar 2023The present review summarizes findings of recent studies examining the epidemiology, pathophysiology, and treatment of type 4 renal tubular acidosis (RTA) and uric acid... (Review)
Review
PURPOSE OF REVIEW
The present review summarizes findings of recent studies examining the epidemiology, pathophysiology, and treatment of type 4 renal tubular acidosis (RTA) and uric acid nephrolithiasis, two conditions characterized by an abnormally acidic urine.
RECENT FINDINGS
Both type 4 RTA and uric acid nephrolithiasis disproportionately occur in patients with type 2 diabetes and/or chronic kidney disease. Biochemically, both conditions are associated with reduced renal ammonium excretion resulting in impaired urinary buffering and low urine pH. Reduced ammoniagenesis is postulated to result from hyperkalemia in type 4 RTA and from insulin resistance and fat accumulation in the renal proximal tubule in uric acid nephrolithiasis. The typical biochemical findings of hyperkalemia and systemic acidosis of type 4 RTA are rarely reported in uric acid stone formers. Additional clinical differences between the two conditions include findings of higher urinary uric acid excretion and consequent urinary uric acid supersaturation in uric acid stone formers but not in type 4 RTA.
SUMMARY
Type 4 RTA and uric acid nephrolithiasis share several epidemiological, clinical, and biochemical features. Although both conditions may be manifestations of diabetes mellitus and thus have a large at-risk population, the means to the shared biochemical finding of overly acidic urine are different. This difference in pathophysiology may explain the dissimilarity in the prevalence of kidney stone formation.
Topics: Humans; Uric Acid; Diabetes Mellitus, Type 2; Acidosis, Renal Tubular; Hyperkalemia; Hydrogen-Ion Concentration; Kidney Calculi; Nephrolithiasis
PubMed: 36683539
DOI: 10.1097/MNH.0000000000000859 -
Annals of Clinical Biochemistry Jul 1999
Review
Topics: Acidosis, Renal Tubular; Humans; Hydrogen-Ion Concentration
PubMed: 10456202
DOI: 10.1177/000456329903600403 -
Clinical Journal of the American... Sep 2014The human kidneys produce approximately 160-170 L of ultrafiltrate per day. The proximal tubule contributes to fluid, electrolyte, and nutrient homeostasis by... (Review)
Review
The human kidneys produce approximately 160-170 L of ultrafiltrate per day. The proximal tubule contributes to fluid, electrolyte, and nutrient homeostasis by reabsorbing approximately 60%-70% of the water and NaCl, a greater proportion of the NaHCO3, and nearly all of the nutrients in the ultrafiltrate. The proximal tubule is also the site of active solute secretion, hormone production, and many of the metabolic functions of the kidney. This review discusses the transport of NaCl, NaHCO3, glucose, amino acids, and two clinically important anions, citrate and phosphate. NaCl and the accompanying water are reabsorbed in an isotonic fashion. The energy that drives this process is generated largely by the basolateral Na(+)/K(+)-ATPase, which creates an inward negative membrane potential and Na(+)-gradient. Various Na(+)-dependent countertransporters and cotransporters use the energy of this gradient to promote the uptake of HCO3 (-) and various solutes, respectively. A Na(+)-dependent cotransporter mediates the movement of HCO3 (-) across the basolateral membrane, whereas various Na(+)-independent passive transporters accomplish the export of various other solutes. To illustrate its homeostatic feat, the proximal tubule alters its metabolism and transport properties in response to metabolic acidosis. The uptake and catabolism of glutamine and citrate are increased during acidosis, whereas the recovery of phosphate from the ultrafiltrate is decreased. The increased catabolism of glutamine results in increased ammoniagenesis and gluconeogenesis. Excretion of the resulting ammonium ions facilitates the excretion of acid, whereas the combined pathways accomplish the net production of HCO3 (-) ions that are added to the plasma to partially restore acid-base balance.
Topics: Acidosis, Renal Tubular; Biological Transport, Active; Humans; Kidney Tubules, Proximal; Phosphates; Sodium Bicarbonate; Sodium Chloride
PubMed: 23908456
DOI: 10.2215/CJN.10391012 -
Annual Review of Medicine 1969
Review
Topics: Acid-Base Equilibrium; Acidosis, Renal Tubular; Adult; Animals; Bicarbonates; Cataract; Child; Dogs; Fanconi Syndrome; Female; Glaucoma; Glomerular Filtration Rate; Humans; Hydrogen-Ion Concentration; Infant; Intellectual Disability; Kidney Tubules; Potassium; Sodium
PubMed: 4894504
DOI: 10.1146/annurev.me.20.020169.002051 -
Clinical and Experimental Nephrology Aug 2015Renal tubular acidosis (RTA) is essentially characterized by normal anion gap and hyperchloremic metabolic acidosis. It is important to understand that despite knowing... (Review)
Review
Renal tubular acidosis (RTA) is essentially characterized by normal anion gap and hyperchloremic metabolic acidosis. It is important to understand that despite knowing the disease for 60-70 years, complexities in the laboratory tests and their interpretation still make clinicians cautious to diagnose and label types of tubular disorder. Hence, we are writing this mini-review to emphasize on the step wise approach to RTA with some understanding on its basic etiopathogenesis. This will definitely help to have an accurate interpretation of urine and blood reports in correlation with the clinical condition. RTA can be a primary or secondary defect and results either due to abnormality in bicarbonate ion absorption or hydrogen ion secretion. Primary defects are common in children due to gene mutation or idiopathic nature while secondary forms are more common in adults. We are focusing and explaining here in this review all the clinical and laboratory parameters which are essential for making the diagnosis of RTA and excluding the extrarenal causes of hyperchloremic, normal anion gap metabolic acidosis.
Topics: Acid-Base Equilibrium; Acidosis, Renal Tubular; Humans; Kidney Tubules
PubMed: 25951806
DOI: 10.1007/s10157-015-1119-x -
Seminars in Nephrology Jul 2019Acid-base balance is critical for normal life. Acute and chronic disturbances impact cellular energy metabolism, endocrine signaling, ion channel activity, neuronal... (Review)
Review
Acid-base balance is critical for normal life. Acute and chronic disturbances impact cellular energy metabolism, endocrine signaling, ion channel activity, neuronal activity, and cardiovascular functions such as cardiac contractility and vascular blood flow. Maintenance and adaptation of acid-base homeostasis are mostly controlled by respiration and kidney. The kidney contributes to acid-base balance by reabsorbing filtered bicarbonate, regenerating bicarbonate through ammoniagenesis and generation of protons, and by excreting acid. This review focuses on acid-base disorders caused by renal processes, both inherited and acquired. Distinct rare inherited monogenic diseases affecting acid-base handling in the proximal tubule and collecting duct have been identified. In the proximal tubule, mutations of solute carrier 4A4 (SLC4A4) (electrogenic Na/HCO-cotransporter Na/bicarbonate cotransporter e1 [NBCe1]) and other genes such as CLCN5 (Cl/H-antiporter), SLC2A2 (GLUT2 glucose transporter), or EHHADH (enoyl-CoA, hydratase/3-hydroxyacyl CoA dehydrogenase) causing more generalized proximal tubule dysfunction can cause proximal renal tubular acidosis resulting from bicarbonate wasting and reduced ammoniagenesis. Mutations in adenosine triphosphate ATP6V1 (B1 H-ATPase subunit), ATPV0A4 (a4 H-ATPase subunit), SLC4A1 (anion exchanger 1), and FOXI1 (forkhead transcription factor) cause distal renal tubular acidosis type I. Carbonic anhydrase II mutations affect several nephron segments and give rise to a mixed proximal and distal phenotype. Finally, mutations in genes affecting aldosterone synthesis, signaling, or downstream targets can lead to hyperkalemic variants of renal tubular acidosis (type IV). More common forms of renal acidosis are found in patients with advanced stages of chronic kidney disease and are owing, at least in part, to a reduced capacity for ammoniagenesis.
Topics: Acid-Base Equilibrium; Acidosis, Renal Tubular; Ammonia; Animals; Bicarbonates; Homeostasis; Humans; Kidney
PubMed: 31300090
DOI: 10.1016/j.semnephrol.2019.04.004 -
Bone Apr 2023Carbonic anhydrase II deficiency (OMIM # 259730), initially called "osteopetrosis with renal tubular acidosis and cerebral calcification syndrome", reveals an important...
Carbonic anhydrase II deficiency (OMIM # 259730), initially called "osteopetrosis with renal tubular acidosis and cerebral calcification syndrome", reveals an important role for the enzyme carbonic anhydrase II (CA II) in osteoclast and renal tubule function. Discovered in 1972 and subsequently given various names, CA II deficiency now describes >100 affected individuals encountered predominantly from the Middle East and Mediterranean region. In 1983, CA II deficiency emerged as the first osteopetrosis (OPT) understood metabolically, and in 1991 the first understood molecularly. CA II deficiency is the paradigm OPT featuring failure of osteoclasts to resorb bone due to inability to acidify their pericellular milieu. The disorder presents late in infancy or early in childhood with fracturing, developmental delay, weakness, short stature, and/or cranial nerve compression and palsy. Mental retardation is common. The skeletal findings may improve by adult life, and CA II deficiency can be associated with a normal life-span. Therefore, it has been considered an "intermediate" type of OPT. In CA II deficiency, OPT is uniquely accompanied by renal tubular acidosis (RTA) of proximal, distal, or combined type featuring hyperchloremic metabolic acidosis, rarely with hypokalemia and paralysis. Cerebral calcification uniquely appears in early childhood. The etiology is bi-allelic loss-of-function mutations of CA2 that encodes CA II. Prenatal diagnosis requires mutational analysis of CA2. Although this enzymopathy reveals how CA II is important for the skeleton and kidney tubule, the pathogenesis of the mental subnormality and cerebral calcification is less well understood. Several mouse models of CA II deficiency have shown growth hormone deficiency, yet currently there is no standard pharmacologic therapy for patients. Treatment of the systemic acidosis is often begun when growth is complete. Although CA II deficiency is an "osteoclast-rich" OPT, and therefore transplantation of healthy osteoclasts can improve the skeletal disease, the RTA and central nervous system difficulties persist.
Topics: Animals; Child, Preschool; Female; Humans; Mice; Pregnancy; Acidosis, Renal Tubular; Calcinosis; Carbonic Anhydrases; Intellectual Disability; Osteopetrosis; Urea Cycle Disorders, Inborn; Carbonic Anhydrase II
PubMed: 36709914
DOI: 10.1016/j.bone.2023.116684