Concomitant increase in muscle strength and bone mineral density with decreasing IL-6 levels after combination therapy with alendronate and calcitriol in postmenopausal women.

OBJECTIVE: The aims of this study were to assess changes in muscle mass and strength according to changes in bone mineral density (BMD) after alendronate-calcitriol therapy and to assess subsequent changes in common biomarkers for osteoporosis and sarcopenia to establish a common strategy against these coexisting conditions.
METHODS: Thirty-eight women with osteopenia and without conditions affecting calcium metabolism, inflammatory cytokines, acute and chronic medical conditions, and regular endurance exercise completed the study. Appendicular lean mass and BMD were measured, and relative skeletal mass index was determined. Grip strength was measured with a JAMAR hand dynamometer. Serum interleukin-6 (IL-6), protein carbonyl, and parathyroid hormone (PTH) were measured as biomarkers related to bone and muscle mass before and after a 6-month combination therapy with alendronate (5 mg) and calcitriol (0.5 μg).
RESULTS: Baseline serum IL-6 showed significant negative correlations with lumbar BMD and handgrip strength (r = -0.458, P = 0.01, and left hand; r = -0.387, P = 0.03, respectively), whereas serum 25-hydroxy vitamin D level was 13.97 (5.65) ng/mL, compatible with vitamin D insufficiency and inversely correlated with PTH level (r = -0.481, P = 0.005). The observation of secondary hyperparathyroidism in association with 25-hydroxy vitamin D deficiency was absent, in contrast with previous reports. After treatment, the mean IL-6 level decreased by 56.5% (8.9%) (P = 0.0032), lumbar BMD increased by 2.62% (2.87%; P = 0.0002), and average handgrip strength increased by 33.52% (8.34%; P = 0.0001). Posttherapy IL-6 level was not significantly correlated with posttherapy BMD and handgrip strength (r = 0.06, P = 0.76, and r = 0.156, P = 0.45, respectively). However, the degree of IL-6 changed by treatment displayed a significant negative correlation with initial lumbar BMD and a positive correlation with PTH levels.
CONCLUSIONS: Improvement not only in lumbar BMD but also in handgrip strength (a representative parameter for sarcopenia) has been observed with 6 months of alendronate-calcitriol combination therapy. Initial IL-6 levels display an inverse relationship with pretreatment lumbar BMD and handgrip strength. The degree of change in IL-6 levels induced by the combination therapy is correlated with the initial degree of the catabolic status of the bone, indicated by markers such as PTH and the severity of lumbar BMD derangements.