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A human autoantibody to renal collecting duct cells associated with thyroid and gastric autoimmunity and possibly renal tubular acidosis.

A complement fixing autoantibody reacting with certain renal collecting duct cells, possibly so called dark cells, is described in 113 patients. Clinically, the antibody was strongly associated with thyroid disorders and pernicious anaemia. The patients also showed a markedly increased frequency of thyroid antibodies and antibodies to gastric parietal cells and to intrinsic factor. One of the patients had a distal renal tubular acidosis (RTA) and pernicious anaemia. The antibody was also found in all of three other patients with either latent or manifest RTA. RTA is associated with various immunological diseases, and the renal collecting duct cell antibody may turn out to be a marker of this disorder, either involved in its pathogenesis or representing a secondary phenomenon.

Acidosis, Renal Tubular↗

Cellular phosphate in renal tubular acidosis.

In two infants with distal renal tubular acidosis phosphate depletion was observed in the extracellular and intracellular compartments of the erythrocytes. Treatment corrected this disturbance over a period of several months. Cell phosphate deficiency may contribute to the adverse effects of renal tubular acidosis on bone.

Acidosis, Renal Tubular↗

The syndrome of renal tubular acidosis with nerve deafness.

Two brothers with renal tubular acidosis and nerve deafness are described. Studies of the physiopathological characteristics of the renal acidification defect show that the defect is limited to the distal tubule. Renal tubular acidosis with nerve deafness is a distinct nosologic entity that is determined by an autosomal recessive trait.

Acidosis, Renal Tubular↗

An experimental renal acidification defect in patients with hereditary fructose intolerance. II. Its distinction from classic renal tubular acidosis; its resemblance to the renal acidification defect associated with the Fanconi syndrome of children with cystinosis.

In adult patients with hereditary fructose intolerance (HFI) fructose induces a renal acidification defect characterized by (a) a 20-30% reduction in tubular reabsorption of bicarbonate (T HCO(3) (-)) at plasma bicarbonate concentrations ranging from 21-31 mEq/liter, (b) a maximal tubular reabsorption of bicarbonate (Tm HCO(3) (-)) of approximately 1.9 mEq/100 ml of glomerular filtrate, (c) disappearance of bicarbonaturia at plasma bicarbonate concentrations less than 15 mEq/liter, and (d) during moderately severe degrees of acidosis, a sustained capacity to maintain urinary pH at normal minima and to excrete acid at normal rates. In physiologic distinction from this defect, the renal acidification defect of patients with classic renal tubular acidosis is characterized by (a) just less than complete tubular reabsorption of bicarbonate at plasma bicarbonate concentrations of 26 mEq/liter or less, (b) a normal Tm HCO(3) (-) of approximately 2.8 mEq/100 ml of glomerular filtrate, and (c) during acidosis of an even severe degree, a quantitatively trivial bicarbonaturia, as well as (d) a urinary pH of greater than 6. That the fructose-induced renal acidification defect involves a reduced H(+) secretory capacity of the proximal nephron is supported by the magnitude of the reduction in T HCO(3) (-) (20-30%) and the simultaneous occurrence and the persistence throughout administration of fructose of impaired tubular reabsorption of phosphate, alpha amino nitrogen and uric acid.A reduced H(+) secretory capacity of the proximal nephron also appears operative in two unrelated children with hyperchloremic acidosis, Fanconi's syndrome, and cystinosis. In both, T HCO(3) (-) was reduced 20-30% at plasma bicarbonate concentrations ranging from 20-30 mEq/liter. The bicarbonaturia disappeared at plasma bicarbonate concentrations ranging from 15-18 mEq/liter, and during moderate degrees of acidosis, urinary pH decreased to less than 6, and the excretion rate of acid was normal.

Acid-Base Equilibrium↗

Distal renal tubular acidosis in polyarteritis nodosa.

Distal renal tubular acidosis developed in a patient with polyarteritis nodosa. The acidosis gradually disappeared, together with most of the other symptoms of systemic vasculitis, after treatment with prednisone and cyclophosphamide. Tubular function test results in this patient suggested that the mechanism underlying the acidification disturbance was acid back-leakage.

Acidosis, Renal Tubular↗

Urinary citrate excretion in the diagnosis of distal renal tubular acidosis.

Since hypocitraturia in distal renal tubular acidosis, we screened the asymptomatic children in three families with familial dRTA, by comparing their 24-hour urine citrate excretion to values obtained in 45 normal children. Subsequent acid loading uncovered four new cases of dRTA suspected because of the finding of hypocitraturia. Because hypocitraturia probably contributes to nephrolithiasis/nephrocalcinosis and subsequent renal damage in dRTA, affected family members were treated with alkali (4 mEq/kg/day), which normalized urine citrate in three children; in a fourth child citrate excretion rose but was not normal. Measurement of urine citrate excretion was superior to other currently proposed screening tests for dRTA (first morning urine pH and sediment, urine concentration).

Acidosis, Renal Tubular↗

An analysis of renal tubular acidosis by the Stewart method.

Renal tubular acidosis (RTA) comprises a group of disorders characterized by a low capacity for net acid excretion and persistent hyperchloremic, metabolic acidosis. To investigate the role of chloride, we performed hypotonic (0.45%) saline-loading experiments in 12 children with alkali-treated distal RTA (dRTA) and compared the results with data obtained from 17 healthy control subjects. In patients, but not in controls, saline loading induced both hyperchloremia and metabolic acidosis. Hyperchloremia was associated with high total and high distal fractional reabsorption of chloride [C(H20)/(C(H20)+C(Cl))]. The increase in plasma chloride varied inversely with the fractional excretion of chloride (C(Cl)) and correlated with the decrease in blood pH. However, the urinary excretion of bicarbonate did not correlate with either changes in blood pH or plasma bicarbonate concentration. Our findings suggest that the mechanism of hyperchloremia was enhanced Cl(-)/HCO(3) (-) exchange by the distal tubule. The resulting metabolic acidosis is better explained by changes in the strong ion difference (the Stewart theory) than by changes in the urine bicarbonate excretion (the traditional theory).

Acid-Base Imbalance↗

Kidney stone inhibitors in patients with renal stones and endemic renal tubular acidosis in northeast Thailand.

Distal renal tubular acidosis (dRTA) is generally associated with hypercalciuria, hypocitraturia, and nephrolithiasis. Our intention was to study glycosaminoglycans (GAGS) and nephrocalcin (NC), two well-known crystal growth inhibitors, in a population with endemic dRTA and nephrolithiasis in northeast (NE) Thailand. We studied 13 patients, six with dRTA and seven with nephrolithiasis with normal or undefined acidification function. Six healthy adults living in the same area as the patients and another six from the Bangkok (BKK) area were used as controls. We measured urinary pH, ammonia, calcium, citrate, magnesium, oxalate, potassium, sodium and uric acid. GAGS were determined by an Alcian blue precipitation method and were qualitated by agarose gel electrophoresis after being isolated using 5% cetyltrimethylammonium bromide at pH 6.0. NC isoforms were isolated as previously described by Nakagawa et al. Citrate was higher in BKK controls ( p<0.04). There was a striking difference among GAGS from BKK when compared with other groups (103.85+/-10.70 vs. 23.52+/-8.11 for dRTA, 22.36+/-14.98 for kidney stone patients and 14.73+/-2.87 mg/ml in controls from the NE region, ( p<0.0001). dRTA and stone-forming patients excrete proportionally more (C+D) than (A+B) NC isoforms ( p<0.05). Also, their NC showed a 100-fold weaker binding capacity of calcium oxalate monohydrate crystals. The ratio of chondroitin sulfate/heparin sulfate in GAGS was approximately 9/1. In addition to the traditional risk factors for nephrolithiasis in dRTA, GAGS and NC might play an important role in the pathogenesis of stone formation in this population.

Acidosis, Renal Tubular↗

Renal tubular acidosis in Kelantan, Malaysia--a case review.

Renal tubular acidosis (RTA) is a defect in urinary acidification in the absence of renal failure. All records of patients admitted to adult medical wards at the University Hospital USM (HUSM), Kelantan between 1986 to 1990 with the diagnosis of renal tubular acidosis were reviewed. Sixteen (16) patients were identified and fulfilled the diagnostic criteria. Their mean age at presentation was 28.9 +/- 0.74 years. The triad of muscle weakness, hypokalaemia and systemic metabolic acidosis were the characteristic features at presentation. Normal serum alkaline phosphatase and skeletal X-rays were noted. Their prognosis were generally good. Their mean serum bicarbonate and potassium on follow up were 17.84 +/- 0.35 and 3.82 +/- 0.05 mmol/L respectively. The importance of regular follow-up and long-term management is emphasised.

Acid-Base Equilibrium↗

Renal tubular acidosis in pregnancy.

Two pre-eclamptic females were seen in consultation by the Renal Service. Both had Renal Tubular Acidosis (RTA). One case resulted from the possible exacerbation of Lupus Erythematosus. The other patient's RTA seemed to be related to ingestion of Dyazide for pre-eclampsia. Delivery of the child in the first case and discontinuance of Dyazide in the second resulted in the abrupt disappearance of RTA.

Acidosis, Renal Tubular↗

Bone mineral density and histology in distal renal tubular acidosis.

BACKGROUND: Chronic metabolic acidosis in distal renal tubular acidosis (RTA) has been implicated in the pathogenesis of enhanced bone resorption and osteopenia, resulting in a loss of bone mineral content. However, histomorphometric and bone densitometric studies of patients who suffered from long-standing distal RTA have rarely been done. METHODS: A cross-sectional study to determine the alterations of bone mineral density (BMD) and histology was done in 14 nonazotemic RTA patients (11 females and 3 males) who had never received alkaline therapy before enrolling into this study. The mean age was 32.7 +/- 11.9 years. BMD measurements and transiliac bone biopsy were done in all patients. Blood chemistries, intact parathyroid hormone level, and a 24-hour urine collection for the determination of urinary calcium, phosphate, sodium, and potassium were obtained from the RTA patients at the time of bone biopsy. Data from 28 age-, sex-, and body mass index-matched, normal controls who were residents in the same area were also obtained. RESULTS: Urinary excretion of calcium was 2.05 +/- 1.59 mmol/day. No patient had hypercalciuria. The serum intact parathyroid hormone level was 15.92 +/- 8.48 pg/mL. RTA patients had lower BMD in most areas when compared with normal controls. There were two patients who suffered from a pathologic fracture at the femur. Bone histomorphometry from RTA patients shows a significantly decreased bone formation rate (0.02 +/- 0.02 vs. 0.07 +/- 0.045 microm(3)/microm(2)/day, P < 0.05), not significantly decreased osteoblastic surface (0.78 +/- 1.03% vs. 2.6 +/- 1.1%) and osteoclastic surface (0.05 +/- 0.03 vs. 0.13 +/- 0.23%), but significantly increased osteoid surface (31.47 +/- 24.52 vs. 5.79 +/- 4.39%, P < 0.05) and osteoid volume (2.95 +/- 3.09 vs. 0.92 +/- 1.05%, P < 0.05) when compared with those of normal controls. There was no difference in osteoid thickness (10.65 +/- 6.10 vs. 8.69 +/- 2.14 microm). Only one distal RTA patient who had a marked increase in osteoid thickness justified the diagnosis of osteomalacia. CONCLUSIONS: This study demonstrates that low bone mass is common in distal RTA patients. Chronic metabolic acidosis results in suppression of bone formation and resorption, which in turn may contribute to the development of low bone mass in distal RTA patients. Although minor elevations in osteoid surface and osteoid volume are found among distal RTA patients, overt osteomalacia is not the predominant bone lesion.

Acidosis, Renal Tubular↗

Nephrocalcinosis in glucose-galactose malabsorption, association with renal tubular acidosis.

We report an association of renal tubular acidosis (RTA) in two children with glucose-galactose malabsorption (GGM), who were found to have nephrocalcinosis. Although GGM has been reported previously with nephrocalcinosis, this report is the first to show that renal tubular acidosis could explain the coexistence of nephrocalcinosis in patients with glucose galactose malabsorption.

Acidosis, Renal Tubular↗

Absence of vacuolar H(+)-ATPase pump in the collecting duct of a patient with hypokalemic distal renal tubular acidosis and Sjögren's syndrome.

Distal renal tubular acidosis (dRTA) is a common complication of autoimmune connective tissue diseases. The underlying pathophysiology of renal tubular acidosis in these syndromes is frequently characterized by impaired hydrogen ion secretion, i.e., secretory defect dRTA. However, the precise molecular events leading to this disturbance remain poorly understood. An opportunity was recently afforded to examine the ultrastructural features of the collecting duct in a patient with Sjögren's syndrome and secretory defect dRTA. Immunocytochemical analysis of a renal biopsy obtained 12 months after the patient's initial presentation demonstrated a complete absence of vacuolar H(+)-ATPase in the collecting duct. Antibodies to the 31- and 56-kd kidney-specific subunits of the H(+)-ATPase pump were used to characterize pump distribution. Interestingly, although antiserum to the CI-:HCO3- anion exchanger (band-3 protein) reacted strongly with normal human kidney and the patient's red blood cells, no immunoreactivity was observed in the patient's collecting duct epithelium. Importantly, electron microscopy of the patient's renal biopsy specimen disclosed cells that ultrastructurally were indistinguishable from intercalated cells. These results suggest that the functional basis of impaired hydrogen ion secretion in this patient was secondary to the absence of intact H(+)-ATPase pumps rather than defective pump function or distribution. The presence of intercalated cells ultrastructurally, but the absence of discernible staining for band-3 protein and H(+)-ATPase, also suggests that the defect in proton secretion may represent a defect involving the assembly of at least two of the ion transport pumps essential for the normal maintenance of acid-base homeostasis by the intercalated cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis, Renal Tubular↗

Renal tubular acidosis. Pathophysiology and diagnosis.

The pathophysiology of renal tubular acidosis is slowly being unraveled, which has implications for the traditional classification of the condition. Nonetheless, the diagnosis of renal tubular acidosis is still easy to establish, and identification of the specific pathophysiological subtype is relatively straightforward. The diagnostic information required usually includes only urinary pH and sodium, potassium, and chloride concentrations and serum potassium level. The urinary pH is not a diagnostic test for renal tubular acidosis, but it serves to distinguish between the various subtypes.

Acidosis, Renal Tubular↗

Treatment of renal lithiasis associated with renal tubular acidosis.

In order to determine the incidence of renal lithiasis in patients with renal tubular acidosis and the effect of therapy on further stone formation, we reviewed the clinical and laboratory manifestations, X-ray findings, and treatment of 48 patients with renal tubular acidosis who were seen at the Mayo Clinic during the years 1970-1980. Thirty-four patients (70%) had radiological evidence of renal lithiasis which was the presenting symptom in 23 (48%) patients. In every instance the calculi were multiple and, with one exception, bilateral. While receiving therapy, 19 patients with renal lithiasis were followed for longer than one year with sequential uroradiographic studies. Fifteen of these patients were treated with oral base alone and thirteen had no evidence of new stone formation or continued growth of existing stones during therapy. The two patients with X-ray evidence of continued stone formation admitted to poor compliance. Four patients received initial treatment with an oral phosphorus supplement. Three of these four patients had radiographic evidence of continued renal stone formation during three, five and eight years of phosphate therapy. We conclude renal lithiasis is a frequent complication of renal tubular acidosis, and adequate base replacement is effective therapy to stop continued stone formation while oral phosphate therapy alone is often ineffective.

Acidosis, Renal Tubular↗

Distal renal tubular acidosis syndromes: a pathophysiological approach.

Ammonium is the most important component of renal acid excretion. A reduced rate of ammonium excretion is the common feature of the group of diseases called distal renal tubular acidosis. We have presented an alternative approach to patients with distal acidification defects based upon the pathophysiology of these disorders. Accordingly, the purpose of this review is to describe a revised classification based on our current understanding of collecting duct hydrogen ion secretion and ammonium addition to the lumen of the distal nephron. We have subdivided these defects into four groups: disorders of the collecting duct proton pump (pump defects); failure to generate and/or maintain an appropriate electrical gradient to favor hydrogen ion secretion (voltage defects); back-leak of hydrogen ions across an abnormally permeable collecting duct membrane (gradient defects), and diminished availability of NH3 in this nephron segment (NH3 defects). These four subtypes can be identified by measuring the urine pH and PCO2 under appropriate circumstances and evaluating the renal excretion of ammonium and potassium.

Acidosis, Renal Tubular↗

Renal tubular acidosis and nerve deafness.

Two brothers are described with renal tubular acidosis and nerve deafness: the elder also had rickets and hypokalaemia. The parents were unaffected. Studies of urinary acidification and bicarbonate excretion were consistent with a distal tubular abnormality. This report strengthens the view previously proposed in similar cases that nerve deafness and renal tubular acidosis constitute a genetic entity. Examination for nerve deafness is indicated in any child with renal tubular acidosis.

Acidosis, Renal Tubular↗

[The significance of citrate, uromucoid and GAG for diagnosis of renal tubular acidosis in patients with urinary calculi].

Renal tubular acidosis (type I) is characterized by alterations that lead to disturbed acidification in the tubule. As a result of these alterations, the excretion of uromucoid (formed in the distal tubule), citrate and glycosaminoglycan (GAG) is considerably reduced. There have been numerous investigations on changes in urine pH, citrate and calcium, but few, if any studies on the excretion of uromucoid and GAG. Apart from calcium, phosphate, pH and urease, the present study investigated the excretion of uromucoid, citrate and GAG in a collective of 41 stone patients with renal tubular acidosis (type I). We found that uromucoid excretion was reduced on 90.5%, GAG in 72.2% and citrate in 96% of cases. The reduction of uromucoid excretion in particular is characteristic of RTA I, and it has the function of a marker.

Acidosis, Renal Tubular↗