Influence of sex, age, and menopause in serum osteocalcin (BGP) levels.

Osteocalcin (bone Gla protein) is a promising marker of bone turnover useful in the diagnosis and follow-up of high turnover osteoporosis. Conflicting results have been reported about its physiological variations according to sex, age, and menopause. Several, but not all, authors have found increased levels in males, with aging, and after menopause. We measured serum osteocalcin in 126 healthy subjects, 57 males and 69 females, aged between 45 and 88 years. Osteocalcin was higher (P less than 0.01) in males (6.24 +/- 0.36) than in females (4.32 +/- 0.34). This sexual difference was significant, too, in subjects younger and older than 60 years. Osteocalcin increased with age, linearly in males (P less than 0.05), and exponentially in females (P less than 0.05). Although there was a difference in age (P less than 0.05), no difference in osteocalcin levels between premenopausal women and women in their first two postmenopausal years was detected, while osteocalcin was significantly increased in women more than two years into menopause. We conclude that osteocalcin in healthy subjects is higher in males than in females and increases with age after 45 years in both sexes. Osteocalcin levels increase in women more than two years beyond menopause, but not only as an effect on aging.