AGE-RELATED (TYPE-II) FEMORAL-NECK OSTEOPOROSIS IN MEN - BIOCHEMICAL-EVIDENCE FOR BOTH HYPOVITAMINOSIS-D-INDUCED AND ANDROGEN DEFICIENCY-INDUCED BONE-RESORPTION

The problem of osteoporosis in men has recently been recognized as an important public health issue, To test the hypothesis that endocrine d eficiency-mediated alterations in bone metabolism might contribute to osteoporotic fracture risk in elderly men, serum levels of 25-hydroxyc holecalciferol (25(OH)D), 1,25-dihydroxycholecalciferol (1,25(OH)(2)D) , intact parathyroid hormone (PTH), testosterone, and estradiol were m easured in 40 males (mean age 73 years) who were consecutively recruit ed within 18 h following a fracture of the proximal femur, and in an e qual number of community-living older men (mean age 72 years) who serv ed as controls, In addition, circulating osteocalcin and urinary excre tion of (deoxy)pyridinoline were determined as markers of bone formati on and resorption, respectively, No differences were observed between the mean serum concentrations of osteocalcin and estradiol, Serum leve ls of 25(OH)D, 1,25(OH)(2)D, and testosterone, however, were decreased in hip fracture patients, When correcting for differences in vitamin D binding protein, differences in 1,25(OH)(2)D did not persist, wherea s serum 25(OH)D was still significantly lower in patients than in cont rols (6.1 +/- 4.3 vs, 7.6 +/- 2.8, p = 0.01), Similarly, a highly sign ificant deficit was observed in the free testosterone index, calculate d from total testosterone and the level of sex hormone binding globuli n (2.6 +/- 1.3 vs, 8.2 +/- 2.9, p < 0.001), Serum PTH and urinary pyri dinium cross-links, however, were markedly increased in the fracture g roup, Moreover, in fracture patients, free 25(OH)D and free testostero ne were both significant and mutually independent negative predictors of (deoxy)pyridinoline excretion, Although limited by its cross-sectio nal design, the present study suggests that both hypovitaminosis D and androgen deficiency may predispose to hone resorption in elderly men and in turn to remodeling imbalance and fracture risk.