[Assessment of formulas of predicted creatinine clearance from serum creatinine]

Much effects have offered to make formulas of predicted creatinine clearance (Ccr) from serum creatinine, sex, age, body weight and height. In this study, we examined 13 kinds of predicted formulas of Ccr that have been previously published. And instead of an actual body weight, we have attempted to use 4 kinds of ideal body weight (two of them reported in Japan, the others in United States) or a lean body weight. A total of 13 subjects were studied (2 healthy males and 11 males with chronic renal disease) to determine Ccr with urine collection for one hour and simultaneous measurement of inulin clearance (Cin). A highly statistical correlation between determined Ccr and predicted Ccr was observed. From predicted formula with one hour urine collection, standard error of estimation (SEE) was smallest. According to determined Cin, the subjects examined was divided into two groups (group A; Cin > or = 50 ml/min, group B; Cin < 50 ml/min). In most formulas, B group had higher correlation than A group, and each regression line got nearer to the identical line (Y = X) and SEE became smaller. The subjects examined were divided into two groups by body mass index (BMI). One is an obese and the other is a nonobese. In an obese group, SEE became smaller when an ideal body weight or a lean body weight were used in formulas instead of actual body weight. We could conclude that the clearance time and ideal or lean body weight of the patients are most important factors to assess predicted Ccr.