CYP27A1 and postmenopausal osteoporosis: In a 3-year research on male osteoporosis, SHBG positively correlated with C-telopeptide of type I collagen (CTx) and free deoxypyridinoline (D-Pyr) which were bone absorption markers after adjustment for age, BMI, and sex steroids in both health controls and postmenopausal osteoporosis (PMOP) patients.