Evaluation of bone mass in young amenorrheic women with anorexia nervosa

BACKGROUND: In the last 10 years an impressive increase in the frequency of food disorders (bulimia and anorexia) in teenagers has been recorded. Food disorders, present especially in girls, (part of more complex relational-familiar disorders) cause progressive repercussions on the general endocrine structure and in particular on the reproductive system of the subject. The most visible effect of this endocrine perturbation is the block of the ovarian function with secondary amenorrhoea and low levels of gonadotropins and estrogens due to the food disorder. In fact the qualitative and quantitative food deficit is responsible for the interruption of the normal hypothalamic and pituitary pulses regulating the correct monthly process of follicular growth. As in the physiological postmenopausal period, very low plasma levels of 17-b-estradiol (<30 pg/ml) can start the bone resorption with bone loss and/or osteoporosis related to the amount and the time of exposure to low levels of estrogens. Objectives: in our study we evaluate the influence of anorexia and amenorrhoea on bone mineral density. METHODS: We evaluate bone mineral density (BMD) with computerised bone mineralometry (MOC), a dual-energy-X-Ray (DEXA), in 18 women with anorexia nervosa and weight loss, 9-12 months amenorrhoea and with low plasma levels of 17-b-estradiol. The BMD was measured at the lumbar spine (L2-L4) and on total body in all subjects enrolled for this study. RESULTS: All the patients showed a decrease on the lumbar BMD with bone loss (49%) or osteoporosis (51%). On the other side the values of total body BMD were around the normal levels (86%) or showed bone loss (14%). CONCLUSIONS: Our data support the hypothesis that lower estrogenic levels associated with anorexia nervosa have an impact on BMD, especially at lumbar level, with early incidence for quantitative and qualitative lower food intake.