Objective: Data concerning bone mineral density (BMD) in bulimia nervosa are contradictory and include both low and normal values. The aim of the present study was to elucidate possible endocrine-and nutrition-related factors predicting BMD in bulimic women.
Design: Cross-sectional study.
Methods: Seventy-seven bulimic patients and 56 age- and body mass index (BMI)-matched healthy controls were examined with respect to BMD (dual energy X-ray absorptiometry) and to serum levels of hormones and metabolic factors.
Results: Bulimics had significantly lower spinal BMD and higher frequency of osteopenia in the total body than controls. Furthermore, bulimic women had significantly lower levels of estradiol-17beta and free thyroxine and significantly higher cortisol levels compared with controls. Among the bulimics, 31.2% had present menstrual disturbance, 51.9% had a history of amenorrhea and 23.4% had previous anorexia nervosa. Subgroups of bulimics with a history of amenorrhea and previous anorexia nervosa had significantly lower total and spinal BMD than controls, whereas those without such history did not differ from the controls. In univariate analysis, a history of amenorrhea, cortisol, testosterone, previous anorexia nervosa, and BMI showed significant associations with spinal BMD. Multiple regression analysis including all significant variables revealed previous anorexia nervosa to be the strongest determinant of spinal BMD, accounting for 34% of the variance, while associations between endocrine factors and BMI disappeared.
Conclusions: Low bone mass in bulimics may be explained by previous anorexia nervosa, whereas endocrine variables related to BMD seem to be secondary determinants that are dependent on previous anorexia nervosa and BMI.