IGF-1 and Bone Loss in Women Anorexia Nervosa

II. SPECIFIC AIMS

Severe osteopenia is a prevalent complication of anorexia nervosa (AN), affecting over half of all women with this disease. Loss of 25-50% of total bone mass occurs frequently and is often permanent. Although anorexia nervosa affects from 0.5-1.0% of college age women, no successful therapeutic interventions have been developed for osteoporosis in this population. Bone loss in anorexia nervosa is characterized by reduced bone formation coupled with increased bone resorption. Anorexia nervosa results in a deficiency of testosterone. Testosterone administration reduces bone resorption and data suggest that low-dose testosterone replacement therapy can increase surrogate markers of bone formation. Bisphosphonates are now well established to decrease bone resorption and improve bone density in severely osteopenic postmenopausal women. However, there are few data regarding the use of this antiresorptive therapy in women with severe pre-menopausal bone loss. Our preliminary data demonstrate that administration of a bisphosphonate decreases bone resorption and increases bone mass in women with AN after 6 and 9 months. These are the first data to demonstrate a striking increase in bone density in such women. We will test the hypothesis that a combined strategy to increase bone formation and decrease bone resorption by combining testosterone with a bisphosphonate will increase bone mass in anorexia nervosa.

The following hypotheses will be tested:

Specific Aim 1. Testosterone, a nutritionally dependent bone trophic factor, is a critical determinant of decreased bone formation in anorexia nervosa, and administration of physiologic testosterone will increase bone formation and lean body mass in this disease

We will investigate in women with anorexia nervosa whether: