Wells J C, Strickland S S
Dunn Nutrition Unit, Cambridge.
Eur J Clin Nutr. 1996 Oct;50(10):668-71.
To evaluate the effect of different methods (plateau or back extrapolation) of calculating total body water (TBW) from deuterium dilution in an environment characterised by high water turnover. The back extrapolation model is assumed to be more accurate when water turnover is high.
Cross-sectional study with measurement of body composition by deuterium dilution and conventional anthropometry.
Rural Sarawak, Malaysia.
24 adults of the Iban population.
TBW was significantly different by method of calculation (P < 0.0001), and mean fat free mass was lower by 1.3 kg using the back extrapolation technique, equivalent to a mean 3.1 (s.d. 0.8)% reduction. The same 1.3 kg difference was equivalent to a mean 16.6 (s.d. 12.3)% increase in fat mass using the back extrapolation technique. Back extrapolation values were used in subsequent analyses. Percentage fat correlated significantly with BMI and skinfold thicknesses in females, but only with BMI in males. Fat mass was significantly correlated with skinfolds and BMI in both sexes. Fat free mass was correlated with BMI in both sexes.
The back extrapolation method produced values for fat mass that differed substantially from those obtained by the plateau method. The difference between calculation methods could be lessened by using saliva samples in place of urine. Back extrapolation values for body fat correlated well with anthropometric measurements in females, less well in males. This difference is due to characteristics of the study population.
评估在水周转率较高的环境中，通过氘稀释法采用不同方法（平台法或反向外推法）计算总体水（TBW）的效果。当水周转率较高时，假定反向外推模型更为准确。
采用氘稀释法和传统人体测量法测量身体成分的横断面研究。
马来西亚砂拉越农村。
24名伊班族成年人。
计算方法不同，TBW存在显著差异（P < 0.0001），采用反向外推技术时，平均去脂体重低1.3千克，相当于平均降低3.1（标准差0.8）%。同样1.3千克的差异，采用反向外推技术时，相当于脂肪量平均增加16.6（标准差12.3）%。后续分析采用反向外推值。女性的体脂百分比与BMI和皮褶厚度显著相关，而男性仅与BMI显著相关。男女的脂肪量均与皮褶厚度和BMI显著相关。男女的去脂体重均与BMI相关。
反向外推法得出的脂肪量值与平台法得出的值有很大差异。用唾液样本代替尿液样本可减少计算方法之间的差异。女性身体脂肪的反向外推值与人体测量指标相关性良好，男性则相关性较差。这种差异是由于研究人群的特征所致。
