Compromised bone density 11.4 years after diagnosis of anorexia nervosa

This investigation evaluated bone density in 36 premenopausal women (X +/- SD age = 29.5 +/- 8.4 years) an average of 11.4 years after diagnosis for anorexia nervosa. Twenty-nine women were aged 20-45 years, and seven were aged 16-19 years. Body composition, age of menarche, length of amenorrhea, estrogen exposure, and lumbar spine and proximal femur bone density were determined. Average appendicular bone density for those greater than or equal to 20 years was found to meet World Health Organization T score criteria for osteopenia: total femur T = -1.22 and femoral neck T = -1.33. The average total lumbar Z score for all 36 participants was -0.95, which was 90% of the mean for their age, and the mean Z scores for adolescent subjects were within 91% of the mean for their age (Z = -0.84). Years of estrogen exposure were correlated with lumbar mineral content (r = 0.50, p = 0.002). A modest but significant inverse relationship was observed between length of amenorrhea and femoral and lumbar bone density. The total proximal femur and trochanteric bone densities were best predicted, using stepwise regression, by the number of years after diagnosis and years of amenorrhea, respectively (R-2 = 0.23, p = 0.02 and R-2 = 0.21, p = 0.04). Lumbar density was best predicted by years of amenorrhea and current percent of ideal body weight (%IBW) (R-2 = 0.25, P = 0.02). Length of amenorrhea, estrogen exposure, and %IBW independently contribute to axial and appendicular bone density. Because of risk for compromised bone density, women with a history of anorexia nervosa should be followed longitudinally to maximize premenopausal bone replacement.