Anthropometric measurement-based estimates of body water in children on peritoneal dialysis

Abstract

Total body water (TBW) is a critical body component in healthy children and those with disease, particularly those with kidney failure. There are gold standard methods to measure TBW directly, but they are expensive and cumbersome. Some require exposure to ionizing radiation. The ability to accurately and precisely estimate TBW from anthropometric data offers an opportunity to be more cognizant of TBW. Such estimates have been published and updated over the past 50 years, and are reviewed. They each perform well in the subjects in which they were developed, but do not seem to work as well when applied to different populations. An aggregate approach may be the most precise way to estimate TBW based upon anthropometric measures. Estimating TBW, accepted to also be the volume of distribution of urea, in patients on dialysis is also emphasized. The measure of dialysis adequacy, Kt / V requires the ability to estimate or measure V, which is essentially TBW. For patients on peritoneal dialysis, V must be estimated to determine Kt / V. TBW estimating formulas developed in healthy children do not perform well at all in children on peritoneal dialysis. Formulas to estimate TBW in children on PD have been developed. They have been validated in a separate cohort of children. Still, these formulas are not precise in children who are at the extremes of hydration or degree of body fat. The ideal approach to estimate TBW in children on PD is yet to be determined.