Bone mineral density in estrogen-deficient young women.

Abstract

Osteoporosis primarily affects postmenopausal women. However, young women with estrogen deficiency also are at increased risk for low bone density. The aim of the study was to assess bone density and associated risk factors for reduced bone density in young, estrogen-deficient women using primary ovarian insufficiency (POI) as the disease model. We conducted a cross-sectional study at a tertiary care research center. We studied women with POI (n = 442), concurrent controls (n = 70), and matched controls from NHANES III (n = 353). We measured bone mineral density (BMD) using dual-energy x-ray absorptiometry. Patients on average had 2-3% lower BMD at L1-L4, femoral neck, and total hip (P < 0.01 at all sites). The modifiable risk factors for BMD below the expected range for age (Z-score <-2) were: more than 1-yr delay in diagnosis of estrogen deficiency (P = 0.018), low (<32 ng/ml) vitamin D levels (P = 0.002), estrogen replacement nonadherence (P = 0.002), low calcium intake (P = 0.005), and lack of exercise (P = 0.005). As compared to Caucasians, African-American and Asian women with POI were 3.18 and 4.34 times more likely, respectively, to have Z-scores below -2 (P = < 0.0001 for both). Race was an overall risk factor, but on regression modeling, not an independent predictor of low bone density. Women with POI have lower bone density compared to regularly menstruating women. Compared to Caucasians, minority women with estrogen deficiency are more likely to have BMD below the expected range for age. This racial disparity appears to be related to a combined effect of several modifiable risk factors. Delay in diagnosis of POI also contributes to reduced bone density by delaying proper therapy.