Anorexia nervosa and related eating disorders

Bone health in eating disorders

Eating disorders (EDs) put adolescents and young adults at risk for impaired bone health. Low bone mineral density (BMD) with ED is caused by failure to accrue peak bone mass in adolescence and bone loss in young adulthood. Although ED patients diagnosed with bone loss may be asymptomatic, some suffer bone pains and have increased incidence of fractures. Adolescents with ED are prone to increased prevalence of stress fractures, kyphoscoliosis and height loss. The clinical picture of the various EDs involves endocrinopathies that contribute to impaired bone health. Anorexia nervosa (AN) is characterized by low bone turnover, with relatively higher osteoclastic (bone resorptive) than osteoblastic (bone formation) activity. Bone loss in AN occurs in both the trabecular and cortical bones, although the former is more vulnerable. Bone loss in AN has been shown to be influenced by malnutrition and low weight, reduced fat mass, oestrogen and androgen deficiency, glucocorticoid excess, impaired growth hormone-insulin-like growth factor 1 axis, and more. Bone loss in AN may not be completely reversible despite recovery from the illness. Treatment modalities involving hormonal therapies have limited effectiveness, whereas increased caloric intake, weight gain and resumption of menses are essential to improved BMD.

Endocrine manifestations of eating disorders

CONTEXT

The endocrinopathies associated with eating disorders involve multiple systems and mechanisms designed to preserve energy and protect essential organs. Those systems that are most affected are in need of significant energy, such as the reproductive and skeletal systems. The changes in neuropeptides and in the hypothalamic axis that mediate these changes also receive input from neuroendocrine signals sensitive to satiety and food intake and in turn may be poised to provide significant energy conservation. These adaptive changes are described, including the thyroid, GH, and cortisol axes, as well as the gastrointestinal tract.

EVIDENCE ACQUISITION

Articles were found via PubMed search for both original articles and reviews summarizing current understanding of the endocrine changes of eating disorders based on peer review publications on the topic between 1974 and 2009.

CONCLUSION

The signals that control weight and food intake are complex and probably involve multiple pathways that appear to have as a central control the hypothalamus, in particular the medial central area. The hypothalamic dysfunction of eating disorders provides a reversible experiment of nature that gives insight into understanding the role of various neuropeptides signaling nutritional status, feeding behavior, skeletal repair, and reproductive function.

Menstrual irregularity and stress fractures in collegiate female distance runners

From 240 questionnaires, we investigated the prevalence of stress fractures in competitive collegiate female long distance runners and its relationship to menstrual history. The runners were divided into three groups according to their menstrual history: very irregular 69/240 (0 to 5 menses/year), irregular 51/240 (6 to 9 menses/year), and regular 120/240 (10 to 13 menses/year). Stress fractures occurred in 49% of the very irregular runners, 39% of the irregular runners, and 29% of the regular runners. The majority of the stress fractures occurred in the tibia. Runners who had never used oral contraceptives were over twice as likely to have had a stress fracture when compared with runners who had used oral contraceptives for more than 1 year. These data suggest that female distance runners who have a history of irregular or absent menses and who have never used oral contraceptives may be at an increased risk for developing a stress fracture. When amenorrheal runners were separated from the very irregular group, an alarming trend was noted in eating behavior disorders. Forty-seven percent of the amenorrheal group, 20% of the one to five menses/year group, 10% of the irregular group, and 7% of the regular group admitted to an eating behavior disorder.