Predicted and Measured Creatinine Clearance for the Estimation of Renal Graft Function: New Tools from Body Composition Analysis

Aim of this study was to evaluate, in Renal Transplant Recipients (RTR), a new method to predict Creatinine Clearance (Ccr) from Plasma Creatinine (Pcr) and from the value of Body Cell Mass (BCM). The values of BCM were obtained, from body impedance analysis (BIA) using an impedance plethysmograph, in 87 RTR with different graft function. The ratios of 24-hour Urinary Creatinine Excretion (Ucr) over BCM were calculated in 30 RTR. In the remaining 57 RTR, Ccr was predicted from Pcr and individual values of BCM (BCM Ccr), using the mean ratio Ucr/BCM found in the first group of patients. In the same patients, Ccr was predicted according to Cockcroft and Gault (CG Ccr). The mean of triplicate measurement of 24-hour Ccr (24 h Ccr), obtained by the standard formula Ucr x Vol/min/Pcr, was used as the reference value of renal graft function. BCM Ccr had a better agreement with 24 h Ccr than CG Ccr, particularly in patients with graft failure. Thanks to its simplicity, accuracy and reproducibility, BCM Ccr is more suitable than 24-hour Ccr to estimate graft function. In the meantime, the body composition data gives useful information for the evalutation of nutritional status and of the equilibrium of body fluid compartments.