Anorexia nervosa
Anorexia nervosa can have serious implications if its duration and severity are significant and if onset occurs before the completion of growth, pubertal maturation or prior to attaining peak bone mass. Both height gain and pubertal development are dependent on the release of growth hormone and gonadotrophins (LH and FSH) from the pituitary gland. Suppression of gonadotropins in patients with anorexia nervosa has been frequently documented. In some cases, especially where onset is pre-pubertal, physical consequences such as stunted growth and pubertal delay are usually fully reversible. Height potential is normally preserved if the duration and severity of anorexia nervosa are not significant and/or if the illness is accompanied with delayed bone age (especially prior to a bone age of approximately 15 years), as hypogonadism may negate the deleterious effects of undernutrition on stature by allowing for a longer duration of growth compared to controls. In such cases, appropriate early treatment can preserve height potential and may even help to increase it in some post-anorexic subjects due to the aforementioned reasons in addition to factors such as long-term reduced estrogen-producing adipose tissue levels compared to premorbid levels.