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The syndrome of renal tubular acidosis and nerve deafness. Discordant manifestations in dizygotic twin brothers.

The syndrome of renal tubular acidosis (RTA) and nerve deafness is a distinct nosological entity that is inherited as an autosomal recessive trait. We studied a pair of dizygotic twin brothers both with nerve deafness but only one with RTA. Distal RTA was diagnosed in twin A because of inappropriately high urinary pH (6.9) and low net acid excretion (40.0 muEq/min per 1.73 m2) in the presence of hyperchloraemic metablic acidosis, and fractional bicarbonate excretion of 1.6% at a normal serum bicarbonate concentration. The urine minus blood PCO2 differences (U-B PCO2) during a neutral sodium phosphate load and in alkaline urine induced by bicarbonate supplementation were: 11 and 0 mm Hg, respectively. Twin A developed nephrocalcinosis and, after a 9.5-year follow-up period, was 5.3 cm taller than his brother. Twin B remained asymptomatic. Periodic determinations of blood pH and serum bicarbonate were normal and urine pH decreased to 4.6 in the face of ammonium chloride-induced metabolic acidosis. The U-B PCO2 assessed in alkaline urine was 33.5 mm Hg. Audiograms demonstrated bilateral nerve deafness in both brothers. The presence of deafness without RTA has not been previously reported in this syndrome. This report also shows that a primary distal acidification defect is responsible for the RTA observed in this syndrome.

Acidosis, Renal Tubular↗

Preservation of intercalated cell H(+)-ATPase in two patients with lupus nephritis and hyperkalemic distal renal tubular acidosis.

In patients with Sjögren's syndrome and a secretory-defect distal renal tubular acidosis (dRTA), absence of vacuolar H(+)-ATPase from collecting duct intercalated cells has been reported. The H(+)-ATPase was examined in two patients with lupus nephritis and hyperkalemic (presumed voltage defect) dRTA. Both patients had a positive urine anion gap, alkaline urine despite acidemia, no rise in urine PCO2 with alkaluria, a urine pH > 5.5, and urine potassium excretion rate not significantly increased after 80 mg of intravenous furosemide. In both patients, immunocytochemistry of renal biopsy frozen sections with an anti-H(+)-ATPase monoclonal antibody showed bright staining of the proximal tubule brush border and collecting duct intercalated cells. In one patient, routine immunofluorescence analysis of a frozen section of her kidney biopsy with antihuman IgG showed staining of the collecting duct, indicative of autoantibodies to this segment. Moreover, rat kidney sections incubated with her serum showed labeling of the intercalated cells. On immunoblots of human kidney microsomal membranes performed with serum from both patients, an immunoreactive polypeptide was observed at M(r) approximately 56 kD that was not seen with control serum. Neither patient's sera reacted with affinity-purified bovine H(+)-ATPase or with lysates from 293 cell fibroblasts in which either of both isoforms of the human H(+)-ATPase B subunit (56 kD) were expressed. These findings demonstrate that the spectrum of dRTA includes the preservation of H(+)-ATPase in intercalated cells, in patients with presumed voltage defect dRTA. Moreover, some patients may have autoantibodies to the intercalated cells that are not directed to subunits of the H(+)-ATPase.

Acid-Base Equilibrium↗

The primary hereditary form of distal renal tubular acidosis: clinical and genetic studies in 60-member kindred.

A distal (type 1) renal tubular acidosis (RTA-1) has been studied in 60 of 69 living members of a large family "HK" and two unrelated small families. The "HK" family, including 28 RTA-1 subjects, presents the first large family with only primary RTA-1 reported to date. The genetic situation in this family confirms the autosomal dominant transmission of the hereditary primary RTA-1 suggested previously on the basis of a few small families. Our data show that, in contrast to the secondary hereditary form, RTA-1 in its primary hereditary form is always complete and often tolerated (asymptomatic). It occurs in non-hypercalciuric families with no clinical variants observed in family members without RTA-1. In our series some clinical abnormalities commonly associated with RTA-1, such as nephrocalcinosis and growth retardation, appeared only in three cases among offspring when both parents were affected. The appearance of such abnormalities, taken as consequences of chronic acidosis in RTA-1, could be favored by the genetic background and/or the homozygosity for the RTA-1 gene. Linkage studies between RTA-1 and 10 genetic markers have been carried out. Results show that only ABO, MNS, GM and RH loci are informative for linkage analysis and none of these loci can be suggested as linked to RTA-1 locus.

Acid-Base Imbalance↗

On the mechanism of toluene-induced renal tubular acidosis.

This study was aimed to investigate the pathogenesis of toluene-induced renal tubular acidosis (RTA). In 5 individuals addicted to toluene sniffing we documented the occurrence of hypokalemia and hyperchloremic metabolic acidosis associated with inability to lower urine pH below 5.5 (6.06 +/- 0.24). Overall kidney bicarbonate reabsorption was normal or enhanced, a feature characteristic of the distal form of RTA (DRTA). These findings resemble those found during the administration of amphotericin B, a drug felt to cause DRTA by increasing hydrogen ion (H+) back-diffusion in the collecting tubule. In toluene sniffers, the urine pCO2 measured in a highly alkaline urine was reduced (47 +/- 8.8 mm Hg), suggesting a decrease in the rate of collecting tubule H+ secretion rather than H+ back-diffusion. To investigate these two mechanisms of altered distal acidification more directly we studied the effect of toluene on acidification by the urinary turtle bladder, an epithelial analogue of the mammalian collecting tubule. In this preparation, toluene resulted in a decrease in the rate of H+ secretion measured by either the pH stat technique or the reverse short circuit current. When mucosal pH was progressively lowered to examine H+ secretion against an H+ gradient, toluene-treated bladders displayed a significant decrease in proton conductance but the lowest mucosal pH required to nullify H+ secretion, (MpH) JH = O, was not different from that of control bladders (4.05 +/- 0.29 and 3.90 +/- 0.13, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Renal Tubular↗

Antimicrobial-associated renal tubular acidosis.

OBJECTIVE: To review the literature documenting the association of various antimicrobial medications with the development of renal tubular acidosis (RTA). DATA SOURCES: A search of the English literature via MEDLINE (1966-November 2003) and International Pharmaceutical Abstracts (1970-November 2003) was conducted to identify human reports of RTA associated with various drugs from all available classes of antimicrobial agents. Major search terms included renal tubular acidosis, acidosis, antibiotics, and antimicrobials. Bibliographies of selected articles were also searched to identify additional reports of RTA. STUDY SELECTION AND DATA EXTRACTION: Case reports, observational studies, and experimental studies documenting the association of any antimicrobial agent with the development of RTA were included. DATA SYNTHESIS: Antimicrobial-associated RTA is a relatively uncommon adverse effect, with most reports involving amphotericin B, trimethoprim/sulfamethoxazole, and outdated tetracycline. These agents may induce RTA either through direct tubular toxicity or as a function of their pharmacologic action. The time course for the development of RTA varies depending on the antimicrobial utilized. In most instances, RTA is reversible; however, some patients may experience prolonged recovery after the offending agent is removed. CONCLUSIONS: Given that antimicrobial-associated RTA is a relatively uncommon adverse effect, review of the patient's drug regimen may reveal these agents as otherwise unrecognized causes of RTA. Likewise, underlying causes of RTA other than medications must be ruled out. Diagnosing antimicrobial-induced RTA may be difficult, given many of these agents may be used in combination and some are intrinsically nephrotoxic.

Acidosis, Renal Tubular↗

Bilateral spontaneous steinstrasse and nephrocalcinosi associated with distal renal tubular acidosis.

Bilateral spontaneous steinstrasse from the ureteropelvic junction to the distal ureter complicating distal renal tubular acidosis has not been described. We report a case and discuss the clinical presentation, radiographic and metabolic findings, and treatment. Relief of obstructive uropathy with extracorporeal shock wave lithotripsy led to the resolution of the heavy steinstrasse burden.

Acidosis, Renal Tubular↗

Newborn renal tubular acidosis associated with prenatal maternal toluene sniffing.

Sniffing of volatile organic solvents containing toluene, such as acrylic paints, glues, adhesives, paint thinners, varnishes and shoe polishes, has become increasingly frequent in recent years. Renal tubular acidosis is one of a number of human complications reported in the offspring of mothers inhaling toluene during pregnancy. This article reports a case of a premature newborn with renal tubular acidosis probably due to maternal sniffing of paint containing toluene. Characteristics of this condition are described as well as its medical management. With increasing frequency of maternal glue and paint sniffing, more cases of newborn renal tubular acidosis will likely appear. Physicians should be prepared to manage neonatal tubular acidosis that may accompany maternal toluene sniffing in order to lessen newborn morbidity and/or mortality.

Acidosis, Renal Tubular↗

On the mechanism of renal potassium wasting in renal tubular acidosis associated with the Fanconi syndrome (type 2 RTA).

The mechanism of renal potassium wasting in renal tubular acidosis associated with the Fanconi syndrome (type 2 RTA) was investigated in 10 patients, each of whom had impaired proximal renal tubular reabsorption of bicarbonate as judged from a greater than 15-20% reduction of renal tubular bicarbonate reabsorption (THCO(3) (-)) at normal plasma bicarbonate concentrations. When the plasma bicarbonate concentration ([HCO(3) (-)]p) was experimentally increased to normal levels in three patients with a fractional potassium excretion (C(K)/C(in)) of less than 1.0 during acidosis, C(K)/C(in) and urinary potassium excretion (U(K)V/C(in)) increased strikingly and concurrently with a striking increase in urinary sodium (U(Na)V/C(in)) and bicarbonate (U(HCO3-)V/C(in)) excretion. When [HCO(3) (-)]p was increased to normal levels in two patients with a C(K)/C(in) of greater than 1.0 during acidosis and in whom U(Na)V/C(in) and U(HCO3-)V/C(in) were already markedly increased, C(K)/C(in) did not increase further. When [HCO(3) (-)]p was decreased to subnormal levels in a patient given ammonium chloride, U(K)V/C(in), C(K)/C(in), and U(HCO3-)V/C(in) decreased concurrently. In the six patients in whom [HCO(3) (-)]p was maintained at normal levels (oral alkali therapy) for 2 months or longer, C(K)/C(in) was directly related to the urinary excretion rates of sodium and bicarbonate, hence was directly related to the magnitude of reduction of THCO(3) (-) at normal [HCO(3) (-)]p; C(K)/C(in) was greater than 0.55 in all six patients and greater than 1.0 in four. In eight patients with classic RTA (type 1 RTA), proximal renal tubular reabsorption of bicarbonate was largely intact as judged from a trivial reduction of THCO(3) (-) at normal [HCO(3) (-)]p. When [HCO(3) (-)]p was either increased from subnormal to normal levels, or decreased from normal to subnormal levels, U(HCO3-)V/C(in) remained essentially constant, and U(K)V/C(in) did not change significantly. When correction of acidosis was sustained, U(HCO3-)V/C(in) remained a trivial fraction of that filtered, and C(K)/C(in) was consistently less than 0.55. These results provide evidence that renal potassium wasting in type 2 RTA is physiologically separable from that in type 1 RTA and in part the result of a reduction in the rate at which the proximal tubule reabsorbs bicarbonate and the distal delivery of supernormal amounts of sodium bicarbonate. With an increased stimulus to distal sodium reabsorption, indicated by the finding of hyperaldosteronism, delivery to the distal nephron of supernormal amounts of sodium with the relatively impermeant bicarbonate anion would be expected to increase intraluminal negativity in the distal nephron, and as a consequence, increase potassium secretion and promote renal potassium wasting.

Acidosis, Renal Tubular↗

[Pathophysiology and diagnosis of renal tubular acidosis].

Intrinsic defects in tubular transport mechanisms of the kidney may cause impairment of urinary acidification or a loss of base equivalents, thereby inducing systemic metabolic acidosis. Different types of this disorder termed renal tubular acidosis (RTA) can be distinguished based on the localization of the disturbance along the nephron (proximal vs. distal) and their association with potassium transport (hypo-/hyperkalemic). Except for the proximal type RTA results in positive acid balance and negatively impacts on bone metabolism and the formation of kidney stones. The diagnosis is based on analysis of acid/base status, urinary pH and determination of ammonium excretion after an oral acid load. Both functional defects of specific tubular transport mechanisms and global impairment of renal tubular function can be causative of RTA. Their therapy is based on treatment of the primary disease process and correction of acidosis by alkali supplementation.

Acidosis, Renal Tubular↗

Proximal renal tubular dysfunction in primary distal renal tubular acidosis.

Low-molecular-weight (LMW) proteinuria has been described in patients with primary distal renal tubular acidosis (dRTA). However, other proximal renal tubular dysfunctions have rarely been reported. In this report we describe reversible and multiple proximal renal tubular cell dysfunctions in a patient with dRTA. A 4-year-old girl was admitted to our hospital for investigation of short stature and proteinuria. Laboratory studies revealed a hyperchloremic metabolic acidosis without aciduria, hypokalemia, hypouricemia with uricosuria, hypercalciuria, LMW proteinuria, phosphaturia, and generalized aminoaciduria. The patient was diagnosed as having dRTA with multiple proximal renal tubular dysfunctions. All proximal renal tubular dysfunction subsided 1.5 years after starting alkali therapy. The precise pathogenic mechanisms underlying the development of multiple proximal renal tubular dysfunctions in dRTA remained unclear. However, proximal renal tubular endosomal dysfunction resulting from a profound intracellular acidosis caused by vacuolar H+-ATPase dysfunction or hypokalemic nephropathy might contribute to the development of proximal renal tubular dysfunctions in patients with dRTA.

Acidosis, Renal Tubular↗

Renal tubular acidosis following intestinal bypass: an etiological study.

Nine cases of the distal type of renal tubular acidosis (RTA) following intestinal bypass were found. Diagnosis was based on inability to acidify the urine to pH values below 5.40 despite systemic acidosis. Acidosis, if not present, was induced by giving ammonium chloride 0.1 g/kg body weight. Patients were examined for diseases known to cause RTA but no already known etiological factor was found. Hyperoxaluria was found in eight of the nine cases with RTA, while not present in patients without RTA or in obese control patients. A causal relationship between hyperoxaluria and RTA is suggested though not proved. Cases reported in the literature of renal damage following bypass are summarized and discussed in relation to presence of hyperoxaluria and RTA.

Acidosis, Renal Tubular↗