Creatinine clearance in the elderly: a comparison of direct measurement and calculation from serum creatinine.

In 53 patients, aged over 70 years and admitted as urgent cases, creatinine clearance was determined biochemically in 24-hour urine and serum. The adjusted creatinine clearance value was compared with the values obtained by the formulas of Cockcroft and Gault [Nephron 16: 31-41, 1976], Kampmann et al. [Acta med. scand. 196: 517-520, 1974] and Hallynck et al. [Clin. Pharmacol. Ther. 30: 414-421, 1981] where creatinine clearance can be estimated from the serum creatinine concentration. A significant connection was found between the adjusted creatinine clearance and the values by the formula of Cockcroft and Gault (r = +0.46), compared with the formula of Kampmann et al. (r = +0.53), although only a small correlation was seen in comparison with the formula of Hallynck et al. (r = +0.30). A very high correlation of the obtained values was found by the formulas of Cockcroft and Gault and Kampmann et al. (r = +0.99) and also a significant correlation with the formula of Hallynck et al., (r = +0.56). By comparing the values according to formulas of Kampmann et al. and Hallynck et al. a significant connection was obtained (r = +0.59). The method of Cockcroft and Gault could be used as a fast analysis of creatinine clearance in older patients with great individual variation, as could the formula of Kampmann et al., but the determination of creatinine clearance by a biochemical method is a reliable reference.