307.1 Anorexia Nervosa - Associated laboratory findings
Although some individuals with Anorexia Nervosa exhibit no laboratory abnormalities, the semistarvation characteristic of this disorder can affect most major organ systems and produce a variety of disturbances. The induced vomiting and abuse of laxatives, diuretics, and enemas can also causea number of disturbances leading to abnormal laboratory findings.
Hematology: Leukopenia and mild anemia are common; thrombocytopenia occurs rarely.
Chemistry: Dehydration may be reflected by an elevated blood urea nitrogen (BUN). Hypercholesterolemia is common. Liver function tests may be elevated. Hypomagnesemia, hypozincemia, hypophosphatemia, and hyperamylasemia are occasionally found. Induced vomiting may lead to metabolic alkalosis (elevated serum bicarbonate), hypochloremia, and hypokalemia, and laxative abuse may cause a metabolic acidosis. Serum thyroxine (T) levels are usually in the low-normal range; triiodothyronine (T) levels are decreased. Hyperadrenocorticism and abnormal responsiveness to a variety of neuroendocrine challenges are common.
In females, low serum estrogen levels are present, whereas males have low levels of serum testosterone. There is a regression of the hypothalamic-pituitary-gonadalaxis in both sexes in that the 24-hour pattern of secretion of luteinizing hormone (LH) resembles that normally seen in prepubertal or pubertal individuals.
Electrocardiography: Sinus bradycardia and, rarely, arrhythmias are observed.
Electroencephalography: Diffuse abnormalities, reflecting a metabolicencephalopathy, may result from significant fluid and electrolyte disturbances.
Brain imaging: An increase in the ventricular-brain ratio secondary to starvation is often seen.
Resting energy expenditure: This is often significantly reduced.