JIMD Reports, Volume 42

Maureen Evans, Kay Nguo, Avihu Boneh, Helen Truby, Evans, Maureen, Nguo, Kay, Boneh, Avihu, Truby, Helen

To compare the measurement of total body water (TBW) and fat-free mass (FFM) using the criterion method of deuterium dilution space ((2)H2O) with bioelectrical impedance analysis (BIA) using a portable QuadScan 4000, Bodystat(®) in children and adolescents with phenylketonuria (PKU). Sixteen patients with PKU, median age is 12.5 (range 5-20.6) years, were recruited into this cross-sectional study. TBW was measured by both deuterium dilution and BIA on the same occasion as per a standard protocol. FFM was estimated from predictive equations. There was no significant difference between TBWDeut and TBWBIA (p = 0.344) or FFMDeut and FFMBIA (p = 0.111). TBWDeut and TBWBIA were highly correlated (r = 0.990, p < 0.0001), as were FFMDeut and FFMBIA (r = 0.984, p < 0.0001). Bland-Altman plots demonstrated that there was no proportional bias between the criterion method, TBWDeut, and the test method TBWBIA, in estimating TBW (β = -0.056, adjusted r (2) = 0.069, p = 0.169) or FFM (β = -0.089, adjusted r (2) = 0.142, p = 0.083). Our results suggest that when compared with the criterion method, the QuadScan 4000, Bodystat(®) can reliably be used to predict TBW and FFM in patients with PKU. We suggest that due to the portability and non-invasive approach, this method can reliably be used to monitor body composition in the outpatient clinic setting, to further improve the monitoring and assessment of nutritional status in PKU.