Assessment of total body water and lean body mass from anthropometry, Watson formula, creatinine kinetics, and body electrical impedance compared with antipyrine kinetics in peritoneal dialysis patients.

Background. Indirect methods such as anthropometry ( A), Watson formula ( W ), creatinine kinetics (CK ), and body electrical impedance (BEI ) are increasingly applied to determine total body water ( TBW ) and lean body mass (LBM ) in dialysis patients. These Introduction methods share the disadvantage that they have been validated for healthy men only. We studied which of In every nutritional survey of maintenance dialysis these four commonly applied methods can best be used patients, protein and energy malnutrition and wasting routinely in CAPD patients. are mentioned, affecting at least one-third of this Methods. TBW estimates obtained from A, W, CK, population [1 ]. A large proportion of patients on and BEI were compared with those obtained by a gold chronic ambulatory peritoneal dialysis (CAPD) show standard (antypirine distribution volume, ADV) in signs of malnutrition, possibly due to losses of protein eight CAPD patients. In addition, several BEI equa- and decreasing dietary intake of protein and energy: tions to derive lean body mass (LBM ) were compared for instance 41.6% of 224 CAPD patients from six with LBM estimated by ADV in order to determine centres in an international study on nutritional assesswhich equation is the most valuable for the assessment ment [2 ]. No significant differences between the nutriof LBM by BEI in CAPD patients. tional status of haemodialysis and CAPD patients have Results. TBW as ADV was 41.4±6.6 (mean±SD) L. been found [3 ]. TBW estimated by W, A and CK underestimated ADV Malnutrition is associated with an increased morbidby a mean±SD of 2.3±13, 5±8.4 and 12.3±10.9% ity [4]. The same holds true for Kt/V [5 ], a urea respectively. TBW as measured by BEI overestimated kinetic parameter of dialysis adequacy, which is a ADV by 2.5±8.8%. The correlation coefficients strong predictor of serum albumin concentration and between ADV‐TBW and TBW estimated by the indir- hence a powerful predictor of death in CAPD [6 ]. ect methods were r=0.88 ( A), r=0.87 (BEI ), r=0.82 Accurate determination of total body water in dialysis (CK ), and 0.68 ( W ). patients is important for assessment of fluid excess, for LBM estimated by ADV was 56.7±8.9 dialysis prescription by Kt/V, and for assessment of (mean±SD) kg; LBM by different BEI equations body composition or nutritional status. Calculation of ranged from 49.9±7 to 58.1±10.7 kg. total body water ( TBW ) or volume of distribution The correlation coefficient between LBM by ADV ( V ) as 0.6 times body weight is inaccurate, and deterand LBM according to the various BEI equations mination of these variables by a tracer dilution method ranged from 0.81 to 0.93. is laborious, invasive, and not well suited for routine Conclusion. A and BEI: can be used to estimate TBW, patient care. Therefore, non-invasive and indirect but the considerable SD (or inaccuracy) makes indi- methods such as anthropometry ( A), Watson formula vidual predictions hazardous. Considering the correla- ( W ), creatinine kinetics (CK), and bioelectrical impedtion coefficients and difference between LBM by ADV ance ( BEI) are increasingly applied for this purpose. and LBM according to different BEI equations, In order to study which of these methods can routinely Deurenberg’s formula can be advocated for use in the best be used for estimation of TBW and lean body estimation of LBM by BEI. mass in peritoneal dialysis patients, we compared estimations obtained by these methods with antipyrine distribution volume. The use of antipyrine in the