LEAN BODY-MASS ESTIMATION BY CREATININE KINETICS

A new technique for estimating lean body mass (LBM) from creatinine ki netics has been developed. It is based on the principle that creatinin e production is proportional to LBM and that, in the steady state, cre atinine production is equal to the sum of creatinine excretion (urinar y and dialytic) and metabolic degradation. This technique was applied to 17 normal subjects, 26 stable, chronic hemodialysis (HD) patients, and 71 stable, chronic peritoneal dialysis (PD) patients. In the HD gr oup, LBM was also determined by bioimpedance in II patients and calcul ated from total body water, measured as the volume of urea distributio n of a sterile urea infusion, in 15 patients. In normal subjects and i n the PD group, LBM was assessed by creatinine kinetics as well as by bioimpedance, near infrared, and anthropometric techniques. In the HD patients, LBM by creatinine kinetics correlated significantly with LBM from total body water and the bioimpedance technique. There was no st atistical difference between the total body water and creatinine kinet ics techniques, but the bioimpedance values were systematically higher than those obtained by the kinetic technique. In the PD group and in normal volunteers, LBM values creatinine kinetics correlated significa ntly with the other methods but were lower. Forty-seven percent of the HD patients and 66% of the PD patients had significantly lower LBM by creatinine kinetics than expected for their sex and age. Estimation o f LBM by creatinine kinetics is proposed as a simple and convenient te chnique for the routine nutritional assessment of dialysis patients.