Bone density patterns after normal and premature menopause

The investigation of the effect of time and type of menopause on bone mineral density (BMD) at different ages.

Five hundred and fourteen women, who had never received any hormonal substitution were studied in a cross-sectional design: 177 with normal (NMP), 210 with surgical (SUMP) and 127 with premature natural (EMP) menopause. Age at menopause was 49.1+/-3.9, 38.3+/-4.7 and 38.1+/-4.2 years (mean+/-1 S.D.), respectively. BMD was measured at L2-L4 vertebrae and proximal femur by the DEXA method.

EMP women presented significantly lower vertebral BMD than NMP women in the 45-55-years segments (P<0.001), but did not differ from SUMP women. This group exhibited lower vertebral BMD than NMP between 45 and 50 years (P<0.001). Regarding femoral neck, EMP women exhibited lower values than SUMP in the 45-50 and 55-65 age segments (P<0.001) whereas SUMP women presented significantly higher BMD values than NMP women after 55 years of age (P<0.001). The percentages of women with vertebral BMD (T-score values) in the osteoporotic range were significantly greater in EMP compared with either NMP or SUMP groups (both P<0.001) whereas in femoral neck lower in SUMP than the other two categories.

Women with either natural or surgical premature menopause exhibit lower BMD of trabecular bone compared with normal menopause women at the age segments 45-55 and 45-50, respectively. However, surgical menopause women exceed normal menopause women in their mixed bone BMD values after 60 years as well as premature natural menopause women at almost all age segments.