Skeletal involvement in eating disorders

The effect of an eating disorder (ED) on bone health and the integrity of the skeletal structure, is an area of significant concern in terms of potential long-lasting, adverse consequences. Adolescence, in particular, represents a crucial developmental stage during which bone density accrues and peak bone mass is achieved. For this reason, EDs elevate the risk for bone loss among adolescents and young adults, and may jeopardize their ability to attain appropriate peak bone mass. Though some patients with EDs may not present with conspicuous symptomatology related to bone health, it is not uncommon for adolescents to develop stress fractures, kyphoscoliosis, or evidence height loss and for adults with EDs to suffer from bone pains and an increased incidence of fractures. In this chapter, we give an overview of the impact of eating disorder symptomatology on the skeletal system for both adults and adolescents with AN. A key characteristic of patients with AN is bone loss, which is evidenced by low bone turnover, greater osteoclastic (bone resorptive) activity as compared to osteoblasic (bone formation) activity, and deterioration in both trabecular and cortical bone, though particularly in the former. Factors that influence bone loss in AN include malnutrition and low weight, reduced fat mass, glucocorticoid excess, impairment of the GH-IGF1 axis, and insufficient levels of estrogen and androgen. On the other hand, in cases of bulimia nervosa (BN), bone loss occurs far less often and usually in patients with a history of low body weight or amenorrhea. From a treatment perspective, the most effective treatment for improving bone mineral density (BMD) is an increase in caloric intake, resulting in weight gain and resumption of menses. Other treatment modalities, such as those involving hormonal therapies, have not been found to have significant efficacy. Still, even in weight-restored patients with AN, long-lasting effects and permanent bone loss may result.