The effects of racial differences on body composition and total body water measured by multifrequency bioelectrical impedance analysis influence delivered Kt/V dialysis dosing.

INTRODUCTION Haemodialysis dosing is traditionally based on urea clearance (Kt/V). Aiming for the same Kt/V target, some racial groups have better survival. We investigated whether body composition differs with ethnicity and may lead to differences in Kt/V delivered. METHODS We compared total body water (TBW) measured by multifrequency bioelectrical impedance analysis (MF-BIA) that calculated from standard anthropometric equations. RESULTS Three hundred and seventy-one adult patients, with a mean age of 58.2 ± 16.6 years, 60.6% of whom were male, 29.1% diabetic, 38.5% Caucasoid, 29.4% African/Afro-Caribbean, 24.8% South Asian and 5.4% East Asian, were studied. TBW measured by MF-BIA differed significantly from that predicted by anthropometric equations. Body fat of women and diabetics was greater, and muscle mass in South Asians was reduced. The difference between the TBW MF-BIA measurement and that of the equation by Watson et al. [11] was associated with % muscle mass (β -10.8, p < 0.001), age (β 0.23, p < 0.001), serum albumin (β -0.24, p < 0.001), body mass index (β 0.91, p = 0.001) and racial origin (β -9.86, p = 0.04). CONCLUSIONS Variation in body composition between ethnic groups potentially leads to over-estimation of delivered dose for some ethnic groups and underestimation for others when using anthropometric equations. MF-BIA assessments of body water should be evaluated as a method for dosing dialysis patients.