Effect of diuretic drugs on creatinine clearance determination.

Diuretic drugs have been reported to alter the glomerular filtration rate and possibly the creatinine excretion by the kidneys. We evaluated the effects of single doses of diuretic drugs on creatinine clearance determination. Ten healthy volunteers were randomized to receive either oral hydrochlorothiazide, oral furosemide, intravenous furosemide, or no treatment in a cross-over fashion during four separate test days with 6-day washout periods. Urine and blood specimens were collected during 24 h after the treatments. Specimens were assayed for creatinine, and the creatinine clearance corresponding to the 4-, 6-, 12-, and 24-h urine collections were calculated. Analysis of variance did not show a statistically significant effect of the diuretic regimens on creatinine clearance over these periods. This study demonstrates that single doses of diuretic drugs do not have significant effect on creatinine clearance determination using urine collected during 4-24-h periods.