[Effect of early menopause by ovariectomy on bone loss]

Early menopause is a well-known risk factor for osteoporosis. It could be an aggravating factor when induced ovariectomy. This study was conducted to compare vertebral bone density and biochemical markers of bone remodelling in patients with spontaneous and induced early and "normal" menopause.

The main biochemical markers of bone remodelling (serum calcium, albumin, alkaline phosphatase, osteocalcin and urinary calcium/creatinine) together with bone density (L2-L4) were measured in 55 women (age 46-77 at inclusion) with spontaneous (n = 16) or surgically induced (n = 39) early menopause (before age 40) and in 227 women (age at inclusion 47-67 years) with normal menopause (after 40 years) either spontaneous (n = 136) or surgically induced (n = 91).

At equivalent ages, vertebral bone density was 7 to 12% lower (p < 0.05) in women with early menopause than in women menopaused after 40. However, the serum levels of alkaline phosphatase and osteocalcin as well as the Nordin index were similar in the two groups. After adjusting for the duration of menopause, women with early menopause did not have a higher bone density than their "normal" menopause counterparts despite their younger age (9 years younger). No differences were observed between spontaneous and surgically induced menopause.

These results suggest that bone loss is more rapid or more long lasting after precocious menopause. Surgically induced menopause does not appear to aggravate bone loss independently of age. Effective prevention of this hormone dependent bone loss is required.