Problems in the metabolic evaluation of renal stone disease: audit of intra-individual variation in urine metabolites.

Preliminary metabolic assessment of patients with renal stones includes measurement of urine metabolites. This paper reports on the degree of intra-individual variation in some key urine metabolites. Over 80 medically untreated patients under initial metabolic investigation were audited from whom 24-h urine results were available as three separate urine pairs collected at intervals not less than 1 month apart.