Most physicians I've talked to find eating disorders confusing, and would rather pass the patient onto an eating disorder program or psychotherapist. This is the worst thing you can do!
A typical patient may come to you for assessment, severely malnourished, with amenorrhea, who may have been exercising and dieting in an effort to get fit or to lose weight. Her mother may say she's been refusing to eat, throwing her school lunches away, or vomiting after meals and using laxatives or diuretics. Your immediate impression might be that this would be a classic case of anorexia nervosa, and that after a routine physical exam and blood tests, she should be referred to an eating disorder specialist.
I would urge you to reconsider this initial impression and make yourself aware that these behaviors may be the result of a chronic digestive tract disorder. Many patients have ended up in eating disorder programs who were finally correctly diagnosed with cholecystitis, gallstones, Chron's disease, Addison's disease, parasitic infections, etc. The morbidity and mortality rates for AN are very high and therefore the patient deserves a thorough medical investigation before making a diagnosis.
It is important not to assume that any abnormality seen in blood tests are simply due to malnutrition. Abnormal enzyme levels may hint at underlying biological disorders.
In our duaghter's case, we found many flawed beliefs held by physicians, such as: "Gallstones would have nothing to do with your daughter's refusal to eat", or "the constipation is a result of her not eating enough", or "her yellow complexion is due to malnutrition", or "her stomach hurts because it has shrunk from not eating enough", or "don't listen to her complaints of stomach pain, she's just being manipulative", or "we occasionally find gallstones in teenagers; it likely has nothing to do with the eating disorder", or "if she's not gaining weight, she must be vomiting after eating",or "she's certainly in no condition to have her gallbladder out".
It is important to understand that if a serious digestive disorder is treated with psychotherapy, the results can be disasterous, not only for the patient, but for the family as well. Mealtimes can become a living hell, with arguing and yelling, trying to get the anorexic child to eat. The anorexic person's life basically falls to pieces, leading often to extreme depression or even suicide. As the attending physician, you have the responsibilty to ensure that there is no underlying illness causing the problem. Remember that what may seem like bizarre behaviors are simply human nature, so don't let that confuse your diagnosis.
Remember also that the diagnostic criteria outlined in DSM-IV are totally inadequate and subjective, and prone to misinterpretation. Many of the behaviors associated with AN are often misinterpreted due to no consideration being given to physical illness.
Of course the top priority is the welfare of the patient, and hospitalization for force feeding may be required; however, it is pertinent to consider that these hospitalizations are extremely traumatizing for the patient, and will likely trigger severe depression and post-traumatic stress disorders. The cognitive-behavioral therapy will also be very traumatizing, since in most programs, few visitors are allowed, and the patient is often placed on a psych ward, which is stigmatizing.
I don't believe anyone desires to be emaciated and malnourished, or wants to kill themselves through starvation. Anorexia can have many biological causes, and you play the most vital role in discovering that cause, and treating the underlying illness.