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Query: UMLS:C0451641 (urolithiasis)
 3,973 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The diurnal urinary oxalate excretion has been determined in 11 patients with urolithiasis and in 7 normal subjects. Increased excretion following meals was observed. The variation from hour to hour was most pronounced in the stone patient group. The relation between oxalate concentration and urinary volume was found to follow a biphasic exponential course. Pyridoxine administration increased oxalate excretion in 9 out of 12 subjects and decreased the excretion in 3 subjects. Ascorbate administration increased oxalate excretion in all 7 subjects studied.
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PMID:The diurnal urinary excretion of oxalate and the effect of pyridoxine and ascorbate on oxalate excretion. 55 87

The serum vitamin A level of the lithiasis patients was found to be low, although vitamin A intake was not different from control subjects. Vitamin C level in blood was not significantly different in the patients as compared with control subjects. The control subjects and urolithiasis patients were also subjected to the oral supplementation of L-tryptophan and glycine. It was observed that neither oxalate nor xanthurenic acid increased in urine after loading. It was concluded that vitamin B6 deficiency does not exist in these cases.
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PMID:Role of vitamins in urolithiasis. 307 83

The present study was undertaken to determine the effect of ingestion of large doses of vitamin C on urinary oxalate excretion and on a number of other biochemical and physicochemical risk factors associated with calcium oxalate urolithiasis. A further objective was to determine urinary ascorbate excretion and to relate it qualitatively to ingested levels of the vitamin and oxalate excretion. Ten healthy males participated in a protocol in which 4 g ascorbic acid was ingested for 5 days. Urines (24 h) were collected prior to, during and after the protocol. The urine collection procedure was designed to allow for the analysis of oxalate in the presence and absence of an EDTA preservative and for the analysis of ascorbic acid by manual titration using 2,6 dichlorophenolindophenol. Physicochemical risk factors such as the calcium oxalate relative supersaturation and Tiselius risk index were calculated from urine composition. The results showed that erroneously high analytical oxalate levels occur in the asence of preservative. In the preserved samples there was no significant increase in oxalate excretion at any stage of the protocol. Ascorbate excretion increased when vitamin C ingestion commenced but levelled out after 24 hours suggesting that saturation of the metabolic pool is reached within 24 hours after which ingested ascorbic acid is excreted unmetabolized in the urine. While transient statistically significant changes occurred in some of the biochemical risk factors, they were not regarded as being clinically significant. There were no changes in either the calcium oxalate relative supersaturation or Tiselius risk index. It is concluded that ingestion of large doses of ascorbic acid does not affect the principal risk factors associated with calcium oxalate kidney stone formation.
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PMID:The effect of ascorbic acid ingestion on the biochemical and physicochemical risk factors associated with calcium oxalate kidney stone formation. 958 1