The Type and Time of Menopause As Decisive Factors for Bone Mass Changes

Background: Early menopause, whether it be natural or surgical, is one of the established risk factors for osteoporosis. Surgical menopause, however, differs from natural menopause owing to the abrupt cessation of estrogen secretion. This study attempts to investigate the influence of menopause type on bone mineral density (BMD) changes.

Methods: Four groups, each consisting of 30 women, were compared: early menopause (EMP), surgical menopause (SUMP) and two groups of natural menopause. The two groups share a similar number of years since menopause (YSM) but have a different chronological age (NMPO), or share a similar age but different YSM (NMPY) to the EMP and SUMP. BMD was measured by the DXA method at L2-L4 vertebrae and proximal femur.

Results: Mean vertebral BMD of EMP was lower than that of SUMP (P < 0.05) and of NMPY (P < 0.001) women. Femoral neck BMD did not differ between SUMP and EMP women but both exhibited significantly lower BMD than either natural menopause groups. BMD of SUMP and vertebral BMD of NMPY women was inversely correlated to chronological age and to number of YSM. Pertaining to T-score values according to the osteoporotic range, NMPO, EMP and SUMP women being homogeneous exhibited significantly lower values than NMPY in the vertebrae (F-ratio = 7.84, P < 0.001). Whereas, in the femoral neck and the trochanter major, EMP and SUMP categories presented significantly lower T-score values than the NMPO and NMPY (F = 3.61, P < 0.01 and 2.8, P < 0.05 respectively).

Conclusion: Women with early menopause exhibit lower vertebral BMD than women of similar age after either surgical or natural menopause. In women of similar age, surgical menopause results in lower vertebral and femoral neck densities compared to natural menopause. Chronological age and the interval after menopause negatively affects bone density in women with similar age whether in surgical or natural menopause.