8. Anorexia / M.C. Champion  

Anorexia is the lack (or loss) of appetite. Anorexia is a common and important, but nonspecific, symptom. It can be a presenting feature in patients with organic or psychological disease. Anorexia and weight loss may be the early signs of malignancy.

The hypothalamus plays a major role in regulating the intake of food. At one time it was generally held that a "satiety center" and a "feeding center" in the hypothalamus exerted the fundamental control over food intake. Stimulation of the satiety center was believed to inhibit the feeding center and gastric hunger contractions. The feeding center was considered to be an integrative station that coordinates complex reflexes associated with food intake. However, it is now believed that control of appetite is best considered as multiple neuropharmacologic interactions in the hypothalamus rather than the effect of a distinct satiety center and feeding center. 

The history should detect other symptoms that may suggest underlying organic or psychological disease. A calorie count is also helpful to assess the actual intake of food. The amount and duration of weight loss should also be documented. 

Physical examination may be normal except for evidence of weight loss. It may point to the underlying organic problem, such as cardiac failure or malignancy.

Many (and perhaps most) illnesses feature a loss of appetite. These range from gastrointestinal disease to malignancy, chronic renal failure, congestive heart failure and many psychiatric diseases, such as depression and anorexia nervosa.

Investigation should exclude organic disease. The approach depends upon the patient’s symptoms and signs. If no physical ailment is discovered, careful screening may be necessary to exclude psychiatric disease.