The complex impedance phase angle of dominant arm: a useful parameter in bone mineral density (BMD) assessment of group 1 post-menopausal women.

Abstract

For widespread osteoporosis (OP) screening, portable and cost-effective screening devices are needed. With 45 menopaused women, when body mass index was below 30 kg.m- 2, the phase angle (PhA) of complex bioimpedance at 5 kHz, measured from the dominant arm, was correlated with dual-energy X-ray absorptiometry (DEXA) measured central bone mineral densities (BMD), for total hip r = 0.493 and for total lumbar r = 0.411, P< 0.05, and the strength of correlation decreased with increasing measurement frequencies. ANOVA tests showed that, below 15 kHz, PhA was a descriptive marker for bone mineral deficiency. By correlating to hip and lumbar bone mineral densities simultaneously, the dominant arm segment PhA was superior to the characteristic frequency fc of the body impedance spectroscopy (BIS) and the PhA of whole-body impedance measurements, of the earlier research works. Due to its medium correlation strength with central BMDs, a PhA measuring device could be considered as a complementary tool to the gold standard (DEXA), for OP screening of group 1 post-menopausal women only. For group 2, with 44 subjects with body mass indices over 30 kg.m- 2, i.e., obese population, the PhA was not correlated with BMD and was no longer a descriptive marker for reduced BMD.