Fig. 2. Bone-specific biochemical turnover markers (BTMs), such as (A) osteocalcin and (B) C-terminal telopeptide of type I collagen (CTX) according to the plasma macrophage migration inhibitory factor quartiles after adjusting for confounding variables. Confounding variables included age, body mass index, current smoking, alcohol intake (≥3 units/day), exercise status (≥30 min/day), parental history of osteoporotic fracture, years since menopause, and 25-hydroxyvitamin D₃. The mean estimated BTMs (95% confidence interval) were calculated using analysis of covariance (ANCOVA). The P values for the trends were generated using multiple linear regression analysis. ^aStatistically significantly different from the lowest quartile (Q1) by ANCOVA.