RAPID AND ACCURATE ESTIMATION OF CREATININE CLEARANCE IN THE MUSCLE-WASTED ELDERLY BY COMPUTED-TOMOGRAPHY

To develop a new method for accurately predicting creatinine clearance (Ccr) in the debilitated elderly without urine collections, the total muscle volume of both thighs (MV thigh), as a new predictive parameter, was calculated using computed tomography in 68 debilitated patients aged 61-92 years. A regression line between 24-hour urinary creatinine excretion and MV thigh was divided by serum creatinine (Scr), and then the following formula was derived: Ccr (ml/min) = 9 x [MV thigh (cm(3)) - 100]/[1,000 x Scr(mg/dl)] Predicted Ccr by the new method more closely correlated with measured Ccr (r = 0.862) than did predicted Ccr by Cockcroft and Gault's method (the C-G method) (r = 0.727), Statistical analysis of prediction error (= predicted Ccr-measured Ccr) suggested that the new method could provide more accurate and less biased estimations of Ccr than did the C-G method, even in patients with renal insufficiency, By using computed tomography, we have proposed a more accurate method for predicting Ccr of the debilitated elderly than the C-G method, although the new method has inherent disadvantages of radiation exposure and high cost.