Bone health in anorexia nervosa.

PURPOSE OF REVIEW

Anorexia nervosa is associated with low bone mineral density (BMD), concerning for an increased risk of fractures, and decreased bone accrual in adolescents, concerning for suboptimal peak bone mass. This review discusses causes of impaired bone health in anorexia nervosa and potential therapeutic strategies.

RECENT FINDINGS

Low BMD in anorexia nervosa is consequent to decreased lean mass, hypogonadism, low insulin-like growth factor-1 (IGF-1), relative hypercortisolemia and alterations in hormones impacted by energy availability. Weight gain causes some improvement in bone accrual, but not to the extent observed in controls, and vitamin D supplementation does not increase BMD. Oral estrogen is not effective in increasing BMD, likely from IGF-1 suppressive effects. In contrast, transdermal estrogen replacement is effective in increasing bone accrual in adolescents with anorexia nervosa, although not to the extent seen in controls. Recombinant human IGF-1 increases bone formation in adolescents, and with oral estrogen increases BMD in adults with anorexia nervosa. Bisphosphonates increase BMD in adults, but not in adolescents, and should be used cautiously given their long half-life.

SUMMARY

Further investigation is necessary to explore therapies for low BMD in anorexia nervosa. Weight gain is to be encouraged. Transdermal estrogen in adolescents, and bisphosphonates in adults, have a potential therapeutic role.