PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ACIDOSIS, RENAL TUBULAR”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 757 records · Page 42Linked to original sources
PubMed1992

On the mechanism of impaired distal acidification in hyperkalemic renal tubular acidosis: evaluation with amiloride and bumetanide.

It has been postulated that a distinctive type of hyperkalemic distal renal tubular acidosis (DRTA), referred to as voltage-dependent DRTA, results from diminished potassium and hydrogen ion secretion in the distal nephron, which is due to a suboptimal voltage (lumen negative) as a result of impaired sodium reabsorption. To test for the presence of a voltage-dependent DRTA, we used amiloride (20 mg oral, single dose) and bumetanide (2 mg oral, single dose) to inhibit and to stimulate voltage-dependent potassium and hydrogen ion secretion, respectively. Eighteen patients with hyperkalemic DRTA and seven controls with a comparable degree of renal impairment were studied. Patients were subdivided in two groups on the basis of their ability to lower their urine pH during spontaneous acidosis. Patients in Group I lowered their urine pH to the level of controls (5.29 +/- 0.06 and 5.37 +/- 0.11, respectively) whereas patients in Group II could not lower their urine pH below 5.5 (6.38 +/- 0.11). Patients in Group I and Group II had a similar degree of metabolic acidosis and hyperkalemia whereas controls had neither acidosis or hyperkalemia. Most patients in Group II and all patients in Group I had low plasma aldosterone levels. The administration of amiloride resulted in an increase in urine pH and a decrease in potassium excretion in all three groups. The finding that amiloride, presumably by obliterating the transtubular voltage as a result of blockade of sodium transport, inhibited potassium excretion to about the same extent in both groups of patients and in controls argues against the existence of a voltage-dependent defect. Bumetanide produced a fall in urine pH below 5.5 and an increase in potassium excretion in controls and Group I patients. In Group II patients, bumetanide failed to elicit a fall in urine pH below 5.5 but resulted in an increase in potassium excretion similar to that seen in controls and Group I patients. These findings suggest that a derangement other than a voltage-dependent defect is responsible for the inability, characteristic of Group II patients, to lower their urine pH. It was concluded that the impairment in urinary acidification observed in patients with this subtype of hyperkalemic DRTA is due to a defect in collecting tubule hydrogen secretion that results from H+ ATPase dysfunction rather than from a voltage-dependent defect.

Acidosis, Renal Tubular↗
PubMed2003

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.

Acidosis, Renal Tubular↗
PubMed2000

Acid and mineral balances and bone in familial proximal renal tubular acidosis.

BACKGROUND: Metabolic acidosis caused by increased rates of fixed acid production is associated with increased urinary excretion of Ca and negative Ca balances. Metabolic acidosis caused by a reduced capacity of the kidneys to excrete acid contributes to the development of bone disease in the course of chronic renal failure and may be associated with bone disease among some patients with renal tubular acidosis. METHODS: To assess the effects of life-long metabolic acidosis alone in the absence of other physiological disturbances, we measured the net balances of fixed acid and minerals in two brothers in a Costa Rican family with hereditary proximal renal tubular acidosis. Bone radiographs were assessed, and radial bone densities were measured. On a subsequent occasion, transiliac bone biopsies, following double-tetracycline labeling, were obtained from these two patients and an unaffected brother. RESULTS: During the balance studies, serum [HCO3-] concentrations of the two affected patients were stable at 12.5 +/- 0.9 and 19.2 +/- 0.7 mmol/L, respectively. Their rates of net fixed acid production were normal and appropriate for their body weights, averaging 0.90 and 1.02 mEq/kg/day. Because their distal renal tubular function was normal, they were capable of acidifying their urine maximally, allowing sufficient urinary excretion of titratable acid and ammonium to maintain net acid excretion at a level that matched acid production. Thus, their acid balances were near zero, as observed among healthy subjects, at -1.9 +/- 2.3 and -2.2 +/- 2.2 mEq/day, respectively. Their rates of urinary Ca excretion were normal at 1.6 +/- 0.3 and 2.7 +/- 2.4 mmol/day, and the their balances of Ca and other minerals were close to zero so that ongoing bone loss was not occurring despite the acidosis. Nevertheless, their heights, relative to their ages, were shorter than the heights of their unaffected relatives. Their radial bone densities were lower than normal for their age and sex, and their iliac cortices were thinner than that of their unaffected brother. However, they had no histomorphometric evidence of osteomalacia or osteitis fibrosa, and their rates of bone mineralization were normal. CONCLUSIONS: The results indicate that this chronic metabolic acidosis reduces growth, including that of bone. We speculate, without direct supporting evidence, that bone stores of HCO3-/CO3= are reduced, as has been observed in patients with the metabolic acidosis of chronic renal failure and in experimental metabolic acidosis in animals.

Absorptiometry, Photon↗