Bone density patterns after normal and premature menopause.

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