title: Methodological aspects of examination of 24 hour urinary excretions in outpatients with recurrent urolithiasis.
abstract: In 85 recurrent stone formers, 2 consecutive 24 h urinary excretions were subjected to chemical examination for calcium, uric acid, magnesium and creatinine. 23 patients had hypercalciuria (greater than 6 mmol/24 h), 22 hyperuricosuria (greater than 3.5 mmol/24 h) and 5 hypomagnesuria (less than 2.4 mmol/24 h). In 1/3 of the cases, the diagnosis would have been missed if based on only one of the two collections, rather than on the mean values from both. Calcium-restricted diet 3 days before and during the sampling is not recommended. Hydrochloric acid appeared to be useful as a preservative and to prevent calcium and magnesium precipitation. No significant seasonal variations were found. Heating of the urine sample before analysis of uric acid did not influence the result.
mesh_terms: D000328:Adult; D002118:Calcium / Q000652:urine; D005260:Female; D006801:Humans; D008274:Magnesium / Q000652:urine; D008297:Male; D012008:Recurrence; D013048:Specimen Handling; D014527:Uric Acid / Q000652:urine; D014545:Urinary Calculi / Q000652:urine*
chemical_list: D014527:Uric Acid; D008274:Magnesium; D002118:Calcium