ELEVATED PLASMA-LEVELS OF INTERLEUKIN-6 IN POSTMENOPAUSAL WOMEN DO NOT CORRELATE WITH BONE-DENSITY

OBJECTIVE: To determine if plasma levels of Interleukin-6 (IL-6) across the lifespan correlate with bone density or plasma osteocalcin. DESIGN: Cross-sectional study. PARTICIPANTS: Forty-five healthy community-dwelling volunteers aged 25-74 years. Exclusion criteria were smoking, use of medications known to affect bone metabolism (corticosteroids, heparin, thyroxine, thiazides, and anticonvulsants), and presence of chronic inflammatory disease. MEASUREMENTS: Bone density was measured by dual-energy X-ray absorptiometry at the femoral neck and lumbar spine. Plasma levels of IL-6 and osteocalcin were determined by ELISA and RIA, respectively. RESULTS: Plasma levels of IL-6 increased with advancing age (P < .0001) and correlated with postmenopausal status (P < .0001). No correlation was observed between plasma IL-6 level and bone mineral density at either the lumbar spine or femoral neck, and none was observed with plasma osteocalcin. CONCLUSIONS: The elevation of plasma IL-6 observed following menopause is consistent with the proposed importance of estrogen in the regulation of IL-6. These findings do not provide support for a role of IL-6 in determination of peak bone density or subsequent development of osteoporosis. However, it is possible that plasma levels of IL-6 differ from those in the bone microenvironment.