Association between appendicular skeletal muscle index and bone turnover markers and bone mineral density in postmenopausal osteoporotic women

Abstract

This was a cross-section study of postmenopausal women with osteoporosis/fractures. In multivariate analysis, P1NP was independently and negatively correlated with appendicular skeletal muscle index (ASMI). ASMI was positively correlated with body mass index and bone mineral density and negatively associated with smoking. ASMI assessment is crucial for postmenopausal osteoporotic women.

Purpose: To evaluate the relationship between appendicular skeletal muscle index (ASMI) and bone turnover markers and bone mineral density (BMD) in postmenopausal women with osteoporosis.

Methods: This cross-sectional study recruited 313 postmenopausal osteoporosis/fracture women from the Osteoporosis Prevention and Treatment Center of Keeling Chang Gung Memorial Hospital. Assessment included anthropometric data, medical history, lifestyle factors, 25-hydroxyvitamin D, parathyroid hormone, procollagen type 1 amino-terminal propeptide (P1NP), carboxy-terminal collagen crosslinks (CTX), lateral thoracolumbar spine x-rays, BMD, and ASMI.

Results: The prevalence of low ASMI in postmenopausal women with osteoporosis was 30.0%. The mean value of P1NP (66.2 ± 38.7 ng/mL) and CTX (0.45 ± 0.25 ng/mL) were both higher than the cutoff values proposed as treatment targets. Univariate linear regression analysis showed that ASMI was positively correlated with age, body mass index (BMI), and total hip, femoral neck, and lumbar spine BMD. Smoking and P1NP levels were negatively associated with ASMI. In all multivariable models adjusted for potential confounders, P1NP was consistently and significantly inversely associated with ASMI. Smoking was also negatively associated with ASMI. ASMI showed significant positive correlations with total hip and femoral neck BMD, but not with lumbar spine BMD. BMI and ASMI showed a consistently strong positive correlation.

Conclusion: ASMI not only showed a significant positive correlation with BMD, but also had similar risk factors as BMD. The significant negative correlation between ASMI and P1NP further confirmed the connection between muscle and bone.

Keywords: Bone turnover markers; Appendicular skeletal muscle index; Bone mineral density; Osteoporosis.