Osteoporosis: prevention and treatment in anorexia nervosa.

One of the most serious and potentially permanently disabling medical complications of anorexia nervosa is osteoporosis, which greatly increases the long-term risk of bone fractures. The decreased bone density in patients with anorexia nervosa (AN) is due to the many effects on bone metabolism of amenorrhea, reduced levels of insulin growth factor-1 (IGF-1), high cortisol levels and weight loss. Although estrogen replacement therapy is clearly efficacious in preventing postmenopausal osteoporosis, its efficacy in AN is uncertain. Clinicians caring for patients with AN need to be aware of this because, despite such therapy, there may be an inexorable decline in bone mineral density in what is a relatively young group of patients. AN frequently has its onset during adolescence, when peak bone mass is normally reached, and an anorectic episode in youth may permanently impair skeletal integrity and lead to debilitating fractures and pain. It is important to recognise this formidable risk, counsel AN patients about the longterm and possibly permanent sequelae of low body weight, use densitometry to screen for bone loss and treat it accordingly. The most effective treatment is still early weight restoration and the resumption of menses.