The role of lean body mass as a nutritional index in Chinese peritoneal dialysis patients - Comparison of creatinine kinetics method and anthropometric method

Objective: To compare, in Chinese continuous ambulatory peritoneal dialysis (CAPD) patients, the creatinine kinetics method (LBM-CK) and the anthropom etric method (LBM-AM) for determining lean body mass (LBM). Design: Single-center cross-sectional study. Patients and Methods: We studied 151 unselected CAPD patients (78 males, 73 females). We calculated LBM-CK and LBM-AM using standard formulas. The res ults of the two methods were then compared by the Bland and Altman method. Dialysis adequacy and other nutritional indices, including total Kt/V,weekl y creatinine clearance (CCr), residual glomerular filtration rate (GFR), pr otein nitrogen appearance (PNA), subjective global assessment (SGA), and se rum albumin, were measured simultaneously. Results: The mean age of the patients was 55.6 +/- 12.2 years, and the mean duration of dialysis was 33.6 +/- 28.5 months. The mean body mass index (B MI) was 22.7 +/- 3.7. The average LBM-AM was 43.6 +/- 8.0 kg; the average L BM-CK was 33.0 +/- 9.3 kg. The difference between the calculated LBM-AM and LBM-CK was 10.7 kg, with LBM-AM always giving a higher value; the limits o f agreement were -5.8 kg and 27.1 kg. The difference between the two measur es correlated with residual GFR (Pearson r = 0.629, p < 0.001). After norma lizing for desired body weight, LBM-AM was only modestly correlated with se rum albumin level. No correlations were found between overall SGA score or normalized protein nitrogen appearance (nPNA) and LBM-AM or LBM-CK. Conclusions: In Chinese patients at least, a substantial discrepancy exists between LBM-AM and LBM-CK. The difference is especially marked in patients with significant residual renal function. The optimal method for determini ng LBM remains obscure in Chinese CAPD patients. Moreover, LBM correlated p oorly with other nutritional indices. Multiple parameters should be taken i nto consideration in an assessment of nutritional status of CAPD patients.