Relationships between upper-arm anthropometry and soft-tissue composition in postmenopausal women.

The value of upper-arm anthropometry as a measure of lean- and fat-tissue masses in 140 normal postmenopausal white women was assessed by studying the relationships of these measures to total and regional fat, and lean masses measured by dual-energy x-ray absorptiometry. Midarm circumference (MAC) was highly correlated with total and regional fat masses (r = 0.85-0.89, P less than 0.0001) but less so with lean-tissue masses (r = 0.26-0.34). Triceps-skinfold thickness was also correlated with fat masses (r = 0.70-0.74, P less than 0.0001) but not with lean mass (r = 0.02-0.09). The derived index, arm muscle area (AMA), was less closely correlated with fat mass than was MAC (r = 0.59-0.61), but its correlation with lean-tissue mass was comparable to that for MAC (r = 0.37-0.43). Multiple-regression analysis confirmed that the anthropometric indices were more closely correlated with fat than with lean mass. It is concluded that all these indices are useful measures of fat mass but that none, including AMA, is a specific index of lean-tissue mass in normal postmenopausal women.