Effects of Anorexia Nervosa on Bone Mass in Adolescents

Adolescence is a critical time for bone mineral accretion as between 60-90% of peak bone mass is established during this period, and peak bone mass is a major determinant of bone density and osteoporosis risk during adulthood. Anorexia nervosa (AN) is the third most common chronic illness among adolescent girls, with a prevalence of 0.2-1.0%. Therefore, AN occurs at a time during which patients are the most vulnerable to disruption of bone mineral accretion. Osteopenia is a major co-morbid complication of AN in 50-75% of female adolescents and adult women with this eating disorder. Women with the onset of the disorder during adolescence have more severe osteopenia than women with onset during adulthood. Little is known about the pathogenesis of osteopenia in this adolescent population and there are no established therapies. Improved understanding of bone mineral metabolism and factors which predict recovery of bone mineral accretion are critical in the development of therapeutic strategies to preserve and maximize bone mass in girls with the onset of AN during adolescence. Estrogen is known to be a critical factor in the development of peak bone mass. Although AN is associated with profound estrogen deficiency, there are no controlled studies investigating the effects of estrogen administration in this population. This research proposal will address critical unanswered questions regarding bone abnormalities in adolescents with anorexia nervosa. Defining changes in bone formation with weight recuperation and hormonal variables would provide insight into the factors essential for bone mineral accretion during adolescence, as well as those that predict recovery. Determination of dose-dependent estrogen effects in this population will be key in targeting interventions during the time of active disease, with the long-term goal of preserving peak bone mass accretion in this vulnerable group of patients. Data obtained from women with post-menopausal osteoporosis or from women with AN cannot be extrapolated to adolescent patients who are in an active period of bone growth and mineralization as well as remodeling. Given the increasing prevalence of AN and its profound consequences on bone health, these studies will provide much needed data to enable treatment strategies for this severe co-morbid disease.