Bone turnover markers and sex hormones in men with idiopathic osteoporosis

Background In contrast to osteoporosis in postmenopausal women, osteoporosi s in men has received much less attention. Patients and Methods We determined various biochemical parameters of bone m etabolism and sex hormones in 31 men with idiopathic osteoporosis and 35 ag e matched control subjects. Results In the men with osteoporosis, a significantly increased urinary exc retion of deoxypyridinoline (5.3 +/- 0.2 vs. 4.6 +/- 0.2 nmol mmol(-1) crea tinine; P = 0.033) in addition to increased serum levels of the c-terminal telopeptide of type I collagen (2677 +/- 230 vs. 2058 +/- 153 pmol; P = 0.0 37) were found. While parameters of bone formation were not significantly d ifferent in the patients and controls, serum bone sialoprotein levels were significantly decreased in the patients (3.7 +/- 0.8 vs. 12.4 +/- 4.0 ng mL (-1); P = 0.021). Moreover, in men with idiopathic osteoporosis, lower leve ls of estradiol (91.3 +/- 5.8 vs. 114.6 +/- 7.8 pmol L-1; P = 0.044), highe r levels of sex hormone binding globulin (31.5 +/- 3.1 vs. 24.2 +/- 1.4 nmo l L-1; P = 0.034) and a decreased free androgen index (42.6 +/- 5.2 vs. 56. 4 +/- 5.9; P = 0.016) were seen. Serum estradiol levels correlated negative ly with several parameters of bone resorption. Conclusions In men with idiopathic osteoporosis, bone resorption is increas ed and exceeds bone formation. The excessive bone resorption seen in idiopa thic male osteoporosis may be due to decreased estradiol levels and low lev els of bioavailable testosterone.