Osteopenia and osteoporosis in adult patients with anorexia nervosa: role of nutritional factors

Abstract Objective: to assess the prevalence and predictive factors of bone mineral loss in adult patients with anorexia nervosa (AN). Methods: bone mineral density (BMD) was assessed by DEXA at femoral and lumbar site in 90 adult patients with AN, consecutively admitted to the Unit for Eating Disorders of Padua University. A series of univariate regressions and then stepwise multiple regression models were used to evaluate the effects on BMD of BMI, BMI before illness, fat mass, fat-free mass, muscle mass, muscle strength, calcium and energy intake, IGF-1, physical activity, smoking, duration of illness, age at onset of AN, age of menarche, presence of sporadic menses, and AN subtype. Results: 80% of patients showed a reduced BMD at any site: 51.1% had osteopenia, and 28.9% osteoporosis. In the subgroup of patients with short duration of illness (<2y), 61.3% had osteopenia, and 6.5% osteoporosis. Univariate assessment in the whole group of patients showed a strong association of BMD at any site with BMI, fat-mass, fat-free mass, muscle mass, IGF-1, and duration of illness. Femoral BMD was also associated with smoking, and lumbar BMD with muscle strength. In the stepwise multiple regression analysis, duration of illness and BMI were identified as independent predictors of femoral BMD, accounting for 44% of variance. The independent predictors of lumbar BMD were duration of illness and fat-mass, accounting for 28% of variance. Conclusions: bone mineral loss represents a common complication of AN, also in adult patients with short duration of illness (< 2 years). Nutritional parameters and duration of illness independently predict bone mineral loss.