The accuracy of creatinine clearance with and without urine collection as a measure of glomerular filtration rate

Conventional creatinine clearances involving urine collections over 2, 4 and 24 hours and creatinine clearance predicted from plasma creatinine concentrations without urine collection were compared to glomerular filtration rate (GFR) estimated by 99mTc DTPA clearance in 171 patients with a wide range of GFR. All creatinine clearance methods involving urine collection had standard errors of the estimate of GFR greater than predictions from formulae. Predictions of creatinine clearance by formulae had coefficients of variation of the estimate of approximately 23% when compared to isotopically determined GFR. Creatinine clearances determined by these equations in patients with stable renal function are an easier and at least as accurate a guide to GFR as methods involving urine collection.