The Association of Muscle Mass Measured by D3-Creatine Dilution Method with Dual Energy X-ray Absorptiometry and Physical Function in Postmenopausal Women.

Background The D3-creatine (D3Cr) dilution method provides a direct measure of skeletal muscle. The aim of this study was to compare the association of D3Cr muscle mass with lean body mass (LBM) measured by dual energy x-ray absorptiometry (DXA) and examine its relation with physical function in postmenopausal women. Methods 74 community dwelling women (mean age 82.3±5.4) participated in this pilot study from the Buffalo, New York clinical site of the Women's Health Initiative (WHI). Participants attended a clinic visit which included anthropometric measures, blood draw, DXA scan, measures of physical function, and initiated the D3Cr protocol. Physical function was evaluated using hand grip strength, short physical performance battery (SPPB), and RAND-36 physical function scale. Descriptive statistics and logistic regression models were used to examine the associations of D3Cr muscle mass with functional outcomes. Results D3Cr muscle mass was moderately correlated with DXA LBM (r = 0.50) and DXA appendicular lean mass (ALM) (r = 0.50). Individuals with high D3Cr muscle mass (%) had higher physical function compared to individuals with low muscle mass (%), indicated by high scores on SPPB (OR =5.24; 95% CI: 1.40, 19.58). We observed stronger relationships between high D3Cr and physical function than either DXA-LBM (OR=3.40; 95% CI: 0.88, 13.11) or DXA-ALM (OR=4.15; 95% CI: 1.10, 15.68) and physical function. Conclusions Our findings provide strong preliminary data for the associations of D3Cr muscle mass with measures of physical function in older women. These findings support and extend prior work on D3Cr muscle mass in older men.