Cases reported "Acidosis, Renal Tubular"

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1/36. Distal renal tubular acidosis with severe hypokalaemia, probably caused by colonic H( )-K( )-ATPase deficiency.

    We describe a 21 month old male infant who presented with failure to thrive associated with severe hypokalaemia and metabolic acidosis, together with hypomagnesaemia. Evaluation revealed marked renal and probable faecal potassium wasting, distal renal tubular acidosis, mild urinary magnesium wasting, and a normal gastric pH (gastric H( )-K( )-ATPase). Hypokalaemic forms of metabolic acidosis, such as diabetic ketoacidosis and proximal renal tubular acidosis were ruled out from the clinical picture. The hypokalaemia of distal renal tubular acidosis usually improves with alkali therapy, but this was not observed: despite correction of acidosis with 5 mmol/kg potassium citrate per day, an additional 5 mmol/kg potassium chloride was required to bring serum potassium to 3.5 mmol/l. At 3 years of age potassium was provided in the absence of potential alkali and acidosis ensued; serum bicarbonate fell to 10 mmol/l. Although a specific genetic analysis is not yet possible, the abnormalities are consistent with a novel form of distal renal tubular acidosis. The pathophysiology probably does not stem from defects in the vacuolar H( )-ATPase but more likely from deficient activity of the colonic isoform of H( )-K( )-ATPase that is resident in the medullary collecting duct and mediates potassium absorption and proton secretion.
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2/36. Distal renal tubular acidosis associated with isolated large vestibular aqueduct and sensorineural hearing loss.

    Distal renal tubular acidosis (dRTA) is characterized by a defect in urinary acidification with various degrees of metabolic acidosis; it can be inherited either as an autosomal dominant trait or as a recessive trait. The recessive form is associated in about one third of cases with progressive sensorineural hearing loss (SNHL). We performed a neuroradiological study in 3 consecutive unrelated pediatric patients affected with sporadic dRTA and progressive SNHL that disclosed an enlarged vestibular aqueduct (VA) and endolymphatic sac (ES) in each. The presence of an enlarged VA in our patients with dRTA and SNHL could contribute to the development, or at least the progression, of the hearing impairment. We suppose that the same molecular defect present in both the kidney and the inner ear could be the cause of dRTA and of the development of the enlarged VA and ES.
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ranking = 1883.4390871968
keywords = aqueduct, duct
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3/36. ATP6B1 gene mutations associated with distal renal tubular acidosis and deafness in a child.

    A large proportion of autosomal recessive distal renal tubular acidosis (RTA) is associated with mutations in the ATP6B1 gene encoding the B1 subunit of H -ATPase. H -ATPase is one of the key membrane transporters for net acid excretion in the alpha-intercalated cells of the medullary collecting duct. Sensorineural hearing loss frequently accompanies this type of distal RTA. Mutational analysis of the ATP6B1 gene in a 9-year-old Korean boy with distal RTA and sensorineural hearing loss found 2 heterozygous missense point mutations. Although a single case report, this is the second report documenting ATP6B1 mutations in recessive distal RTA with sensorineural hearing loss after the original report by Karet et al and confirms the novelty of these mutations.
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4/36. A phenocopy of CAII deficiency: a novel genetic explanation for inherited infantile osteopetrosis with distal renal tubular acidosis.

    The rare bone thickening disease osteopetrosis occurs in various forms, one of which is accompanied by renal tubular acidosis (RTA), and is known as Guibaud-Vainsel syndrome or marble brain disease. Clinical manifestations of this autosomal recessive syndrome comprise increased bone density, growth failure, intracerebral calcification, facial dysmorphism, mental retardation, and conductive hearing impairment. The most common cause is carbonic anhydrase ii (CAII) deficiency. Several different loss of function mutations in CA2, the gene encoding CAII, have been described. To date, there have been no exceptions to the finding of CAII deficiency in patients with coexistent osteopetrosis and RTA. Most often, the RTA is of mixed proximal and distal type, but kindreds are reported in which either distal or proximal RTA predominates. We report the molecular genetic investigation of two consanguineous kindreds where osteopetrosis and distal RTA (dRTA) were both manifest. One kindred harbours a novel homozygous frameshift alteration in CA2. In the other, CAII levels were normal despite a similar clinical picture, and we excluded defects in CA2. In this kindred, two separate recessive disorders are penetrant, each affecting a different, tissue specific subunit of the vacuolar proton pump (H( )-ATPase), providing a highly unusual, novel genetic explanation for the coexistence of osteopetrosis and dRTA. The osteopetrosis is the result of a homozygous deletion in TCIRG1, which encodes an osteoclast specific isoform of subunit a of the H( )-ATPase, while the dRTA is associated with a homozygous mutation in ATP6V1B1, encoding the kidney specific B1 subunit of H( )-ATPase. This kindred is exceptional firstly because the coinheritance of two rare recessive disorders has created a phenocopy of CAII deficiency, and secondly because these disorders affect two different subunits of the H( )-ATPase that have opposite effects on bone density, but which have only recently been determined to possess tissue specific isoforms.
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5/36. Absence of H( )-ATPase in cortical collecting tubules of a patient with sjogren's syndrome and distal renal tubular acidosis.

    Distal urinary acidification abnormalities may arise from transepithelial voltage defects, permeability defects, or proton-secretory defects, but tests to determine the cellular mechanisms underlying secretory abnormalities have not previously been reported. A patient with sjogren's syndrome and distal renal tubular acidosis due to a secretory defect is described, whose kidney biopsy was examined by fluorescent immunocytochemistry with an antibody to the M(r) 31,000 subunit of the mammalian kidney vacuolar H( )-ATPase and was compared with normal human kidney. Staining with the anti-H( )-ATPase antibody in normal human kidney was detected in the brush border microvilli and subvillar invaginations of the proximal tubule and in intercalated cells in the collecting duct. A biopsy sample from the patient was devoid of any anti-H -ATPase staining in the intercalated cells. Staining was also absent from the proximal tubule brush border microvilli but was present in the subvillar invaginations. Although autoantibodies to normal human kidney membrane proteins were detected in the serum by immunoblot analysis, no immunocytochemical evidence for anti-intercalated cell autoantibodies was observed in the patient's serum. This report demonstrates that the basis for the proton secretory defect in some patients with distal renal tubular acidosis is likely the absence of H( )-ATPase in the intercalated cells. It also illustrates the potential diagnostic utility of anti-H( )-ATPase antibodies in the classification of distal renal tubular acidoses.
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6/36. Distal renal tubular acidosis associated with large vestibular aqueduct and sensorineural hearing loss.

    CONCLUSIONS: hearing loss and equilibrium dysfunction have different etiologies in patients with large vestibular aqueduct syndrome. We suggest that all children with distal renal tubular acidosis (dRTA) should be subjected to an equilibrium study and audiological evaluation, as well as to a CT or MRI scan. OBJECTIVE: dRTA has been described in association with sensorineural hearing loss, but there are no reported cases that have been examined in detail using audiological and equilibrium studies. We report here a case of progressive sensorineural hearing loss with a large vestibular aqueduct and dRTA, and the results of audiological and equilibrium studies. MATERIAL AND methods: A 31-year-old female presented with hearing loss, tinnitus and vertigo. She had been treated with oral sodium citrate, potassium citrate and potassium chloride supplementation because of dRTA since the age of 1 month. RESULTS: The pure-tone audiogram of the patient was off the scale for the right ear and showed progressive sensorineural hearing loss for the left ear. ice-water caloric testing showed canal paresis on the left side. temporal bone CT and inner ear MRI revealed a large vestibular aqueduct and a large endolymphatic sac on both sides.
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ranking = 2636.8147220755
keywords = aqueduct, duct
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7/36. Distal renal tubular acidosis: alkali heals osteomalacia and increases net production of 1,25-dihydroxyvitamin D.

    In 2 women with distal renal tubular acidosis and osteomalacia, alkali treatment cured the bone disease and was accompanied by marked increases in the serum 1,25 dihydroxyvitamin D concentration, without a significant change in the 25-hydroxyvitamin D concentration.
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8/36. Molecular investigation and long-term clinical progress in Greek Cypriot families with recessive distal renal tubular acidosis and sensorineural deafness due to mutations in the ATP6V1B1 gene.

    The spectrum of distal renal tubular acidosis (dRTA) includes a genetically heterogeneous group of inherited conditions of both autosomal-dominant and recessive mode of inheritance. The basic defect is linked to the renal part of acid-base homeostasis, which is partly achieved by the regulated luminal secretion of H at the apical surface of the alpha-intercalated cells of renal collecting ducts. This is coupled to bicarbonate reabsorption with chloride counter transport across the basolateral membranes. Here, we describe the molecular findings of the first two Greek Cypriot families with recessive dRTA and the long-term clinical findings in four of five affected members. dna linkage analysis with four polymorphic markers flanking the ATP6V1B1 gene on chromosome 2 gave evidence for positive linkage; direct dna analysis by automated dna sequencing revealed that patients in one family were homozygous for mutation 229 1G>T (IVS7 1G>T) and that patients in the second family were compound heterozygous for 229 1G>T and R157C. The mutations were found on four different haplotypes. Both the mutations were previously reported in patients of Turkish origin. Three known polymorphic variants were also identified. The five patients demonstrated the whole clinical spectrum of the disease including death in infancy, failure to thrive, rickets, nephrocalcinosis, nephrolithiasis, and episodes of hypokalemic paralysis. Some of the family members are now in their mid 30s and late 20s, and nephrolithiasis with recurrent renal colics is their main problem. Renal function has remained normal. In conclusion, early diagnosis in infancy and prompt treatment with alkali and potassium supplements is of great benefit to the patient with dRTA and ensures normal growth. The identification of responsible mutations facilitates antenatal or postnatal diagnosis in concerned families and improves the prognosis.
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9/36. 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.
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10/36. Should the urine PCO2 or the rate of excretion of ammonium be the gold standard to diagnose distal renal tubular acidosis?

    A high rate of excretion of ammonium (NH4 ) during chronic metabolic acidosis should rule out the diagnosis of distal renal tubular acidosis (RTA). Bearing this in mind, the purpose of this report is to demonstrate that a low urine minus blood PCO2 difference in alkaline urine (U-B PCO2) is a less reliable indicator of the diagnosis of distal RTA. The patient who is the subject of this report sniffs glue on a chronic, but intermittent basis. He presented with metabolic acidosis (pH 7.20; bicarbonate, 10 mmol/L) and an anion gap in plasma of 20 mEq/L. The urine anion gap (-14 mEq/L) and osmolal gap (185 mmol/L [mOsm/kg] H2O) suggested that there was a high, rather than a low, rate of excretion of NH4 . This was confirmed by direct measurement of NH4 in the urine (101 mumol/min). The high rate of excretion of NH4 suggested that the metabolic acidosis was due, in large part, to an abnormally high rate of production of acid (hippuric acid, because the rate of excretion of hippurate was 76 mumol/min). The U-B PCO2 was low (10 mm Hg) on the second hospital day, after the acidosis was corrected. Potential reasons for the discrepancy between the high rate of excretion of NH4 and the low U-B PCO2 are discussed.
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