Virgili F, D'Amicis A, Ferro-Luzzi A
National Institute of Nutrition, Rome, Italy.
Ann Hum Biol. 1992 Jan-Feb;19(1):57-66. doi: 10.1080/03014469200001922.
In this study a group of 30 women and 30 men aged 60-90 years was examined. Body density was predicted from the sum of four skinfold thickness (SFT) as described by Durnin and Womersley (1974). Body composition, expressed as a percentage of total body weight as fat mass (FM) and fat free mass (FFM) was calculated by means of Siri's formula (Siri 1961). Total body water (TBW) was measured from the dilution of an oral deuterium dose and FFM calculated assuming a hydration of 73.2%. The FM% predicted from SFT showed a slight but not significant decreasing age trend from 28.3% to 25.4% in men, and from 40.3% to 37.8% in women. Body hydration (about 50% of body weight in men and 44% in women) remained constant throughout the age range. FFM obtained from TBW assuming a constant hydration of FFM, was found to be unchanged with age. FM% predicted from SFT was correlated with values obtained from TBW on an individual basis (R2 = 0.38; p less than 0.0001 in men and R2 = 0.31; p less than 0.002 in women), but the scatter was large. The Bland and Altman statistical analysis (Bland and Altman 1986) suggests that the discrepancy between the two estimates tends to be significantly more positive with increasing fatness of the subject. The assumption of a constant hydration of FFM between individuals and with advancing age was tested. The hydration of FFM was calculated as the ratio between TBW (from deuterium dilution) and FFM (estimated from SFT). The wide range of values (50% to 90%) suggests large inter-individual differences. The mean values were lower than commonly reported, and differed with age and sex. In men, FFM hydration steadily decreases with age from the 7th decade (70.2 +/- 7.7%) to the 10th decade (65.9 +/- 8.2%). Women showed higher average figures than those of men and a lower age-associated decline (72.5% and 68.5% respectively). Our results suggest that FFM hydration decreases with age, and this indicates the need to develop age-related correction factors in order to derive FFM from TBW in an elderly population.
在本研究中，对一组30名年龄在60至90岁之间的女性和30名男性进行了检查。按照Durnin和Womersley（1974年）所述，根据四处皮褶厚度（SFT）之和预测身体密度。通过Siri公式（Siri，1961年）计算身体成分，以脂肪量（FM）和去脂体重（FFM）占总体重的百分比表示。通过口服氘剂量的稀释测量全身水含量（TBW），并假设水合率为73.2%来计算FFM。由SFT预测的FM%在男性中呈现出轻微但不显著的随年龄下降趋势，从28.3%降至25.4%，在女性中从40.3%降至37.8%。身体水合率（男性约为体重的50%，女性约为44%）在整个年龄范围内保持恒定。假设FFM水合率恒定，从TBW获得的FFM被发现随年龄没有变化。由SFT预测的FM%与个体从TBW获得的值相关（男性R2 = 0.38；p小于0.0001，女性R2 = 0.31；p小于0.002），但离散度较大。Bland和Altman统计分析（Bland和Altman，1986年）表明，随着受试者肥胖程度增加，两种估计值之间的差异往往显著更偏向正值。对个体之间以及随着年龄增长FFM水合率恒定的假设进行了检验。FFM的水合率计算为TBW（来自氘稀释）与FFM（由SFT估计）的比值。广泛的数值范围（50%至90%）表明个体间差异很大。平均值低于通常报道的值，并且随年龄和性别而不同。在男性中，FFM水合率从第7个十年（70.2 +/- 7.7%）到第10个十年（65.9 +/- 8.2%）随年龄稳步下降。女性的平均数值高于男性，且与年龄相关的下降幅度较小（分别为72.5%和68.5%）。我们的结果表明，FFM水合率随年龄下降，这表明需要制定与年龄相关的校正因子，以便在老年人群中从TBW得出FFM。
