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Prognostic factors for persistent distal renal tubular acidosis after surgery for posterior urethral valve.

Risk factors, including age at presentation, age at surgery, time between presentation and surgery, urodynamic abnormalities, and vesicoureteric reflux, were prospectively studied for the development of distal renal tubular acidosis (DRTA) before surgery and persistent DRTA after surgery in 24 boys with posterior urethral valve (PUV) with normal serum creatinine levels. DRTA was persistent in 11 of 17 boys (65%) at the end of follow-up after intervention. For the development of DRTA before surgery, only a longer time between presentation and surgery (intervening period) turned out to be a significant risk factor on multivariate analysis (beta = -0.13; P = 0.04). Boys with persistent DRTA after surgery had older age at presentation (P = 0.03), older age at surgery (P = 0.001), a longer intervening period (P = 0.0007), and bilateral or severe unilateral reflux (P = 0.04) before surgery. On univariate logistic regression, age at surgery (beta = -0.07; P = 0.04) and intervening period (beta = -0.13; P = 0.02) were found to be significant risk factors for persistent DRTA, but on multivariate analysis, only intervening period was found to be significant (beta = -0.13; P = 0.02). A delay in intervention after noticing voiding symptoms can predict a high incidence of DRTA before intervention and persistent DRTA after surgery in boys with PUV.

Acidosis, Renal Tubular↗

Sibling cases of Vici syndrome: sleep abnormalities and complications of renal tubular acidosis.

Vici syndrome is a rare congenital disorder characterized by albinism, agenesis of the corpus callosum, and developmental delays. Cardiac complications usually cause poor prognosis. We report sibling cases of Vici syndrome, and address complications of renal tubular acidosis. We also demonstrate the significance of serial examinations of brain natriuretic peptides, and discuss the possible early use of a beta-blocker to control cardiomyopathy. A sleep study including polysomnography indicated functional brainstem involvement, in which muscle atonia during non-rapid sleeping eye movements, and bursts of rapid eye movements increased. These findings provide new clues for medical care of patients with Vici syndrome.

Acidosis, Renal Tubular↗

Anion exchanger 1 mutations associated with distal renal tubular acidosis in the Thai population.

We have previously demonstrated that compound heterozygous (SAO/G701D) and homozygous (G701D/G701D) mutations of the anion exchanger 1 (AE1) gene, encoding erythroid and kidney AE1 proteins, cause autosomal recessive distal renal tubular acidosis (AR dRTA) in Thai patients. It is thus of interest to examine the prevalence of these mutations in the Thai population. The SAO and G701D mutations were examined in 844 individuals from north, northeast, central, and south Thailand. Other reported mutations including R602H, DeltaV850, and A858D were also examined in some groups of subjects. The SAO mutation was common in the southern Thai population; its heterozygote frequency was 7/206 and estimated allele frequency 1.70%. However, this mutation was not observed in populations of three other regions of Thailand. In contrast, the G701D mutation was not found in the southern population but was observed in the northern, northeastern, and central populations, with heterozygote frequencies of 1/216, 3/205, and 1/217, and estimated allele frequencies of 0.23%, 0.73%, and 0.23%, respectively. The higher allele frequency of the G701D mutation in the northeastern Thai population corresponds to our previous finding that all Thai patients with AR dRTA attributable to homozygous G701D mutation originate from this population. This suggests that the G701D allele that is observed in this region might arise in northeastern Thailand. The presence of patients with compound heterozygous SAO/G701D in southern Thailand and Malaysia and their apparently absence in northeastern Thailand indicate that the G701D allele may have migrated to the southern peninsular region where SAO is common, resulting in pathogenic allelic interaction.

Acidosis, Renal Tubular↗

Medullary sponge kidney associated with distal renal tubular acidosis in a 5-year-old girl.

INTRODUCTION: Medullary sponge kidney (MSK) is characterized by cystic dilatation of the inner medullary collecting ducts, which causes the kidneys to resemble a sponge. CASE REPORT: Although distal renal tubular acidosis (dRTA) is commonly observed in patients with MSK, we report a 5-year-old girl with MSK who had features of both dRTA (nephrocalcinosis, hypercalciuria, hypocitraturia) and proximal tubular dysfunction (hyperuricosuria, impaired tubular phosphate reabsorption and proteinuria). DISCUSSION: Metabolic acidosis, hypercalciuria, hypocitraturia, tubular phosphate reabsorption and growth retardation in the patient improved with alkali therapy.

Acidosis, Renal Tubular↗

Genetic investigation of autosomal recessive distal renal tubular acidosis: evidence for early sensorineural hearing loss associated with mutations in the ATP6V0A4 gene.

Mutations in the ATP6V1B1 and ATP6V0A4 genes, encoding subunits B1 and 4 of apical H(+) ATPase, cause recessive forms of distal renal tubular acidosis (dRTA). ATP6V1B mutations have been associated with early sensorineural hearing loss (SNHL), whereas ATP6V0A4 mutations are classically associated with either late-onset SNHL or normal hearing. The phenotype and genotype of 39 new kindreds with recessive dRTA, 18 of whom were consanguineous, were assessed. Novel and known loss-of-function mutations were identified in 31 kindreds. Fourteen new and five recurrent mutations of the ATP6V0A4 gene were identified in 21 families. For the ATP6V1B1 gene, two new and two previously described mutations were identified in 10 families. Surprisingly, seven probands with ATP6V0A4 gene mutations developed severe early SNHL between the ages of 2 mo and 10 yr. No mutation was detected in eight families. These data extend the spectrum of disease-causing mutations and provide evidence for genetic heterogeneity in SNHL. The data also demonstrate that mutations in either of these genes may cause early deafness, and they highlight the importance of genetic screening for recessive forms of dRTA independent of hearing status.

Acidosis, Renal Tubular↗

Renal tubular acidosis (RTA): recognize the ammonium defect and pHorget the urine pH.

To maintain acid-base balance, the kidney must generate new bicarbonate by metabolizing glutamine and excreting ammonium (NH4+). During chronic metabolic acidosis, the kidney should respond by increasing the rate of excretion of NH4+ to 200-300 mmol/day. If the rate of excretion of NH4+ is much lower, the kidney is responsible for causing or perpetuating the chronic metabolic acidosis. Thus, the first step in the assessment of hyperchloraemic metabolic acidosis is to evaluate the rate of excretion of NH4+. It is important to recognize that the urine pH may be misleading when initially assessing the cause of this acidosis, as it does not necessarily reflect the rate of excretion of NH4+. If proximal renal tubular acidosis (RTA) is excluded, low NH4+ excretion disease may be broadly classified into problems of NH4+ production and problems of NH4+ transfer to the urine; the latter being due to either interstitial disease or disorders of hydrogen ion secretion. The measurement of the urine pH at this stage may identify which problem predominates. This approach returns the focus of the investigation of RTA from urine pH to urine NH4+.

Acid-Base Equilibrium↗

Renal tubular acidosis and skeletal demineralization in patients on long-term anticonvulsant therapy.

Three children ranging from seven to 12 years of age from unrelated families were given long-term anticonvulsant therapy including acetazolamide (Diamox). These children had rickets and renal tubular acidosis. Investigations have suggested (1) secondary hyperparathyroidism due to hypocalcemia of rickets and (2) prolonged acetazolamide therapy were responsible for acidosis as a result of reduction of bicarbonate reabsorption in the kidney. A clear-cut recovery from acidosis and rickets was seen in two patients following medication with high doses of vitamin D, an oral supplement of phosphorus, and discontinuance of acetazolamide therapy.

Acetazolamide↗

Type-II renal tubular acidosis and ventricular tachycardia in a horse.

A 14-year-old Arabian mare was admitted for lethargy, anorexia, and low fecal output. On the basis of laboratory, physical examination, and electrocardiographic findings, diagnoses of type-II renal tubular acidosis (RTA), impaction of the large colon, and ventricular tachycardia were made. Diagnosis of type-II RTA was based on measurement of a low fractional excretion value for potassium and fractional excretion value for sodium within the reference range. In contrast, horses with type-I RTA have high fractional excretion values for sodium and fractional excretion values for potassium within reference ranges. Treatment consisted of intravenous and oral administration of sodium bicarbonate, intravenous administration of fluids, and oral administration of mineral oil and docusate sodium. Acidosis improved, and ventricular tachycardia resolved with resolution of acidosis. Oral administration of bicarbonate was continued after discharge. The mare had several relapses, which were associated with anorexia and low intake of supplemental bicarbonate. The mare was found dead 2 months after discharge.

Acidosis, Renal Tubular↗

Renal tubular acidosis type 2 with Fanconi's syndrome, osteomalacia, osteoporosis, and secondary hyperaldosteronism in an adult consequent to vitamin D and calcium deficiency: effect of vitamin D and calcium citrate therapy.

OBJECTIVE: To describe a unique example of renal tubular acidosis type 2 (RTA 2) in conjunction with Fanconi's syndrome and osteomalacia consequent to vitamin D and calcium deficiency in an adult without underlying gastrointestinal disease. METHODS: We review the clinical, hormonal, histomorphometric, and micro-computed tomographic findings and the response to therapy with vitamin D and calcium in our patient. RESULTS: On admission, a 33-year-old African American woman had the following laboratory findings: serum ionized calcium 3.8 mg/dL (0.95 mmol/L), venous pH 7.26, bicarbonate 20 mEq/L, chloride 111 mEq/L, alkaline phosphatase 1,192 U/L (20.26 microkat/L) (normal, 40 to 136 U/L), 25-hydroxyvitamin D <5 ng/mL (<12 nmol/L) (normal, 10 to 60 ng/mL), parathyroid hormone 1,620 pg/mL (165.2 pmol/L) (normal, 10 to 60 pg/mL), aldosterone 68.4 ng/dL (1,894.7 pmol/L) (normal, 4.5 to 35.4 ng/dL), supine plasma renin activity 19.8 ng/mL per hour (5.35 ng/L per second) (normal, 0.5 to 1.8 ng/mL per hour), and aminoaciduria. A lumbar spine bone density T-score was -4.6, and a femoral neck T-score was -4.9. An undecalcified tetracycline-labeled bone biopsy specimen showed severe osteomalacia, severe osteoporosis, and peritrabecular fibrosis. A small intestinal biopsy revealed normal findings. Results of an ammonium chloride loading test and a bicarbonate infusion test were consistent with RTA 2. After 24 months of vitamin D and calcium therapy, results of serum and urine chemistry studies and bicarbonate infusion normalized. The lumbar spine T-score improved to -2.0, and the femoral neck T-score improved to -2.7. Bone biopsy specimens demonstrated resolution of the osteomalacia. CONCLUSION: Nutritional vitamin D and calcium deficiency may cause RTA 2, Fanconi's syndrome, and osteomalacia in adults as well as in children.

Acidosis, Renal Tubular↗

Sjögren's syndrome presenting as hypokalemic paralysis due to distal renal tubular acidosis.

A 57-year-old woman presented with a flaccid paralysis, muscle tenderness, and respiratory depression. Laboratory results demonstrated severe hypokalemia with hyperchloremic metabolic acidosis and abnormally acidified urine. The urinary anion gap was positive in the presence of acidemia, thus establishing the diagnosis of distal renal tubular acidosis (DRTA). The patient fully recovered after potassium and alkali replacement. Further investigation revealed Sjögren's syndrome as the underlying cause of DRTA.

Acid-Base Equilibrium↗

[Multiple calcium oxalate stone formation in a patient with glycogen storage disease type I (von Gierke's disease) and renal tubular acidosis type I: a case report].

A case of multiple urinary stones in a patient with glycogen storage disease type 1 (GSD-1) is reported. In spite of the presence of hyperuricemia, these stones did not consist of uric acid, but mainly of calcium oxalate. Laboratory studies revealed distal renal tubular acidosis and hypocitraturia, but no significant abnormality in calcium metabolism. We discussed the mechanism of calcium stone formation in our case, and its prophylactic treatment by oral administration of citrate compound.

Acidosis, Renal Tubular↗

Cell-mediated immunity to human Tamm-Horsfall glycoprotein in autoimmune liver disease with renal tubular acidosis.

Cell-mediated immune responses to Tamm-Horsfall glycoprotein isolated from human urine were investigated using the leucocyte migration test. Abnormal responses were found in 91% of patients with active chronic hepatitis or primary biliary cirrhosis with an associated renal tubular acidosis (R.T.A.) but in only 19% of those without R.T.A. In nearly all of a group of patients without autoimmune liver disease and in a control group of normal subjects results were within normal limits. In addition, using an immunofluorescent technique with rabbit antibody to human Tamm-Horsfall glycoprotein, it was possible to show the presence in human liver cell membrane of material reacting immunologically as Tamm-Horsfall. These findings suggest that the development of an immune response to this glycoprotein, initiated by release of cross-reacting antigens from damaged hepatocytes, could be the mechanism underlying the occurrence of R.T.A. in some patients with autoimmune liver disease.

Acidosis, Renal Tubular↗

A novel neurological disorder with progressive CNS calcification, deafness, renal tubular acidosis, and microcytic anemia.

Progressive calcification of the brain and the spinal cord at early infantile onset was observed in two siblings. They showed growth failure, psychomotor deterioration, deafness, vestibular dysfunction, microcytic hypochromic anemia, abnormal ratios of lymphocyte subpopulations, and slightly decreased bicarbonate on blood gas analysis. Distal renal tubular acidosis was demonstrated in one of them. Carbonic anhydrase II activity was normal. This new hereditary disease might have a defect in a molecule that is present in brain, spinal cord, kidney and hematocytes and is involved in H+/HCO3- production or transport.

Acidosis, Renal Tubular↗

Missense mutations in Na+:HCO3- cotransporter NBC1 show abnormal trafficking in polarized kidney cells: a basis of proximal renal tubular acidosis.

The kidney Na(+):HCO(3)(-) cotransporter NBC1 is located exclusively on the basolateral membrane of kidney proximal tubule cells and is responsible for the reabsorption of majority of filtered bicarbonate. Two well-described missense mutations in NBC1, R510H and S427L, are associated with renal tubular acidosis (RTA). However, the exact relationship between these mutations and NBC1 dysregulation remains largely unknown. To address this question, cDNAs for wild-type kidney NBC1 and its mutants R510H and S427L were generated, fused in frame with NH(2) terminally tagged GFP, and transiently expressed in Madin-Darby canine kidney cells. In parallel studies, oocytes were injected with the wild-type and mutant NBC1 cRNAs and studied for membrane expression and activity. In monolayer cells grown to polarity, the wild-type GFP-NBC1 was exclusively localized on the basolateral membrane domain. However, GFP-NBC1 mutant R510H was detected predominantly in the cytoplasm. GFP-NBC1 mutant S427L, on the other hand, was detected predominantly on the apical membrane with residual cytoplasmic retention and basolateral membrane labeling. In oocytes injected with the wild-type or mutant GFP-NBC1 cRNAs, Western blot analysis showed that wild-type NBC1 is predominantly localized in the membrane fraction, whereas NBC1-R510H mutant was predominantly expressed in the cytoplasm. NBC1-S427L mutant was mostly expressed in the membrane fraction. Functional analysis of NBC1 activity in oocytes by membrane potential recording demonstrated that compared with wild-type GFP-NBC1, the GFP-NBC1 mutants H510R and S427L exhibited significant reduction in activity. These findings suggest that the permanent isolated proximal RTA in patients with H510R or S427L mutation resulted from a combination of inactivation and mistargeting of kidney NBC1, with H510R mutant predominantly retained in the cytoplasm, whereas S427L mutant is mistargeted to the apical membrane.

Acidosis, Renal Tubular↗

Canine distal renal tubular acidosis and urolithiasis.

Distal RTA is characterized by decreased distal renal tubular hydrogen ion secretion, decreased ability to acidify urine, hypercalciuria, hyperphosphaturia, hypocitraturia, and metabolic acidosis. Because of the resulting alterations in urine composition and pH, patients with distal RTA are predisposed to urolithiasis and renal calcification. Diagnosis of distal RTA is important because it is a potentially reversible disorder that, left untreated, may cause nephrocalcinosis, recurrent urolith formation, moderate to severe metabolic acidosis, and renal failure.

Acidosis, Renal Tubular↗

Hashimoto thyroiditis, distal renal tubular acidosis, pernicious anaemia and encephalopathy: a rare combination of auto-immune disorders in a 12-year-old girl.

A case of a 12-year-old girl with a multiple auto-immune disorder is reported. She showed Hashimoto thyroiditis which subsequently developed to hashitoxicosis and distal renal tubular acidosis at 5 years of age, pernicious anaemia at the age of 9 and severe encephalopathy at the age of 12. Laboratory studies revealed very high titres of anti-microsomal and anti-thyroglobulin antibodies and positive gastric parietal cell antibody. As to the encephalopathy, positive oligoclonal IgG bands and high values of IgG index and IgG synthesis ratio in CSF were observed with aggravation of her neurological symptoms. High-dose steroid therapy was effective toward the encephalopathy. Paediatricians should pay careful attention to patients with Hashimoto thyroiditis for association with other autoimmune disorders.

Acidosis, Renal Tubular↗

Case report 668. Carbonic anhydrase II deficiency syndrome (osteopetrosis associated with renal tubular acidosis and cerebral calcification).

A 4-month-old infant with bronchiolitis was found to have hyperdense bones on chest roentgenograms. The diagnosis of osteopetrosis was demonstrated by generalized increased radiological bone density and by a bone biopsy showing persistence of calcified cartilage. The infant also had a mixed proximal and distal renal tubular acidosis requiring as much as 12 mEq/kg per day of sodium bicarbonate. Measurement of his erythrocyte carbonic anhydrase activity revealed a deficiency of CA II. His parents showed values of CA activity that were intermediate between controls and the proband. Thus, this is a patient with the CA II deficiency syndrome; he is the youngest reported case without any family history of osteopetrosis to be diagnosed initially on the basis of his radiographic features.

Acidosis, Renal Tubular↗

Human anion exchanger1 mutations and distal renal tubular acidosis.

The human anion exchanger 1 (AE1 or SLC4A1) gene encodes anion exchanger 1 (or band 3) protein in erythrocytes and in alpha-intercalated cells of the kidney. Thus, AE1 mutations show pleiotrophic effects resulting in two distinct and seemingly unrelated defects, an erythrocyte abnormality and distal renal tubular acidosis (dRTA). Southeast Asian ovalocytosis (SAO), a well-known red blood cell (RBC) defect, which is widespread in Southeast Asian regions, is caused by AE1 mutation due to a deletion of 27 base pairs in codons 400-408 (delta400-408) leading to an in-frame 9 amino-acid loss in the protein. Co-existence of SAO and dRTA is usually not seen in the same individual. However, the two conditions can co-exist as the result of compound heterozygosities between delta400-408 and other mutations. The reported genotypes include delta400-408/G701D, delta400-408/R602H, delta400-408/deltaV850, and delta400-408/A858D. The presence of dRTA, with or without RBC abnormalities, may occur from homozygous or compound heterozygous conditions of recessive AE1 mutations (eg G701D/G701D, V488M/V488M, deltaV850/deltaV850, deltaV850/A858D, G701D/S773P) or heterozygous dominant AE1 mutations (eg R598H, R589C, R589S, S613F, R901X). Codon 589 of this gene seems to be a 'mutational hot-spot' since repeated mutations at this codon occurring in different ethnic groups and at least two de novo (R589H and R589C) mutations have been observed. Therefore, AE1 mutations can result in both recessive and dominant dRTA, possibly depending on the position of the amino acid change in the protein. As several mutant AE1 proteins still maintain a significant anion transport function but are defective in targeting to the cell surface, impaired intracellular trafficking of the mutant AE1 is an important molecular mechanism involved in the pathogenesis of dRTA associated with AE1 mutations.

Acidosis, Renal Tubular↗