Racette S B, Schoeller D A, Luke A H, Shay K, Hnilicka J, Kushner R F
Department of Medicine, University of Chicago, Illinois 60637.
Am J Physiol. 1994 Oct;267(4 Pt 1):E585-90. doi: 10.1152/ajpendo.1994.267.4.E585.
The doubly labeled water method for measuring energy expenditure can be very sensitive to small differences in the ratio of the 2H to 18O isotope dilution spaces. Recently it has been suggested that the average ratio is higher than the 1.03 we previously recommended. We therefore combined the data from 99 recently studied subjects. Subjects (85 females and 14 males) were between the ages of 4 and 78 yr (mean = 34 yr) and between 10 and 52% (mean = 35%) fat. The average 2H-to-18O dilution space ratio was 1.034 +/- 0.014, which was very similar to the original assumption. As in recent reports, we did find that most of the variance (60%) was due to random analytic error and that there was no correlation between the dilution space ratio and age or body fat. However, in contrast to recent reports we found no evidence of a gender difference. Use of the constant dilution space ratio of 1.034 to recalculate CO2 product in published validation studies demonstrated improved accuracy, and thus the value of 1.034 is suggested for use in future studies.
用于测量能量消耗的双标水法对2H与18O同位素稀释空间比率的微小差异可能非常敏感。最近有人提出，平均比率高于我们之前建议的1.03。因此，我们合并了最近研究的99名受试者的数据。受试者（85名女性和14名男性）年龄在4至78岁之间（平均 = 34岁），体脂率在10%至52%之间（平均 = 35%）。2H与18O稀释空间的平均比率为1.034±0.014，这与最初的假设非常相似。与最近的报告一样，我们确实发现大部分方差（60%）是由于随机分析误差，并且稀释空间比率与年龄或体脂之间没有相关性。然而，与最近的报告不同的是，我们没有发现性别差异的证据。在已发表的验证研究中，使用1.034的恒定稀释空间比率重新计算二氧化碳产量，结果显示准确性有所提高，因此建议在未来的研究中使用1.034这个值。
