Gender differences in bone mineral density in epilepsy

Purpose: Bone accrual in adolescence is a major determinant of peak bone mass and risk of osteoporotic fractures later in life. Postmenopausal women are at highest risk, although, both men and premenopausal women with epilepsy experience adverse bone effects. We examined gender differences in bone density in epilepsy. Methods: Cross-sectional study examining age and gender-specific z-score total bone mineral density (z-BMD) in 108 ambulatory children with epilepsy between 6 and 18 years of age (61 females 12.8 +/- 3.6 years; 47 males 12.4 +/- 3.1 years) compared to 35 healthy controls who were first-degree cousins of patients (21 females 13.8 +/- 2.5 years and 14 males 11.7 +/- 2.5 years). Results: Patients with epilepsy accrued lower z-BMD compared to controls (0.27 +/- 0.77 vs. 0.53 +/- 1.1, p < 0.05), and were reduced for both females (0.23 +/- 1.1 vs. 0.47 +/- 0.76; p = 0.14, NS) and males (0.3 +/- 1.1 vs. 0.8 +/- 0.5; p = 0.11, NS). Increasing duration of epilepsy was associated with lower BMD in males (correlation coefficient = 0.06; p = 0.05). Males with >= 6 years of epilepsy experienced the lowest z-BMD compared to controls (-0.89 +/- 0.80 vs. 0.62 +/- 0.80; p = 0.45). Fractures occurred in two females with epilepsy for >= 6 years and z-BMD of -1.5 and -2.7. Conclusions: BMD in both males and females with epilepsy is reduced. Young males with more chronic epilepsy (>= 6 years) had the lowest BMD. Age at onset of epilepsy, growth trends, and hormonal differences may underlie these gender differences. Lower bone accrual in adolescence may contribute to increased fracture risk for both men and women with epilepsy.