Relation of body mass and sex steroid hormone levels to hot flushes in a sample of mid-life women

Objective: Previous studies indicate that obesity is associated with a higher risk of experiencing hot flushes in mid-life women. The reasons for this association are unknown, although altered hormone levels have been associated with both hot flushes and obesity. Thus, this current study tested the hypothesis that obesity is associated with hot flushes in mid-life women through a mechanism involving levels of total and free androgen, free estrogen, progesterone, and sex hormone binding globulin (SHBG). Methods: Women aged 45-54 years were recruited from Baltimore and its surrounding counties. Each participant (n = 628) was weighed, measured, completed a questionnaire, and provided a blood sample that was used to measure estradiol, estrone, testosterone, androstenedione, dehydroepiandrosterone sulfate, progesterone, and SHBG. Results: Obese mid-life women (body mass index (BMI) ≥ 30.0 kg/m2) had significantly higher testosterone, and lower estradiol, estrone, progesterone, and SHBG levels than normal-weight mid-life women (BMI ≤ 24.9 kg/m2) after adjustment for age, race, smoking, and number of days since last menstrual period. The association between obesity and hot flushes was no longer significant after adjustment for estrogens and progesterone, and/or SHBG. Conclusion: These data suggest that obesity may be associated with hot flushes through a mechanism involving multiple hormones and SHBG.