What is unexplained weight loss?

Your weight sometimes changes, depending on how much you eat and exercise. However, drastic weight loss, losing more than 20 pounds when you're not trying to, requires medical attention because it may be a sign of disease.

How does it occur?

If you're not trying to lose weight, the loss may be a symptom, alone or with other symptoms, of disease.

Unexplained weight loss can be caused by:

• decreased appetite

• impaired absorption, which means that food eaten can't be processed properly because of problems in the intestine or pancreas

• loss of nutrients, the chemical and energy sources of the body

• excess demand by the body for energy (calories).

Decreased appetite can be caused by the following:

• poorly fitting dentures or pain in the teeth or mouth

• psychological disorders that upset eating habits (anorexia nervosa and bulimia)

• depression and/or anxiety

• drugs such as digitalis, amphetamines, and antitumor medications

• a high level of calcium in the blood (hypercalcemia)

• a low level of potassium in the blood (hypokalemia)

• alcohol abuse

• viral hepatitis, an inflammation of the liver

• accumulation of body wastes in the blood (uremia)

• congestive heart failure

• cancer of the pancreas, the cancer most commonly associated with weight loss

• cancer or disease of the esophagus, stomach, or digestive tract.

Impaired absorption can be caused by:

• problems with bile and gallbladder (cholestasis)

• not enough enzymes for digestion (pancreatic insufficiency)

• surgery on the stomach (gastrectomy)

• disease of the small intestine

• parasitic infection such as trichinosis, caused by uncooked pork

• drugs such as cholestyramine and cathartics (cause the bowel to empty).

Loss of nutrients can be caused by:

• unchecked diabetes mellitus, when the blood sugar is too high

• long-lasting diarrhea

• vomiting

• proteins or ketones in the urine, related to some kidney diseases.

Excess demand for energy can be caused by:

• overactivity of thyroid glands and excess of thyroid hormones, which speeds up the body's metabolism (hyperthyroidism)

• fever

• cancer

• emotional states, such as manic disease, that cause increased physical activity

• hyperactivity

• amphetamine or other drug abuse.

How is it diagnosed?

To diagnose the underlying cause of weight loss, the doctor will ask about your medical history and give you a physical exam. In addition, the doctor may order various lab tests such as blood tests and x-rays. For example, to determine whether the cause of weight loss is too great a demand for energy by the body, the doctor may order tests for hyperthyroidism.

How is it treated?

First your doctor will work to correct the underlying problem. Then the doctor will also help you with your symptoms. Here are some examples of treatment:

• For severe anorexia, the doctor may prescribe phenothiazines or appetite stimulants.

• For decreased appetite due to hepatitis, the doctor will suggest eating small, frequent meals, especially in the morning when nausea is milder.

• For decreased appetite associated with depression, the doctor may suggest antidepressant medication.

• For impaired absorption caused by pancreatic insufficiency, the doctor may prescribe pancreatic enzyme preparations.

• For bacterial infections, the doctor may prescribe antibiotics.

• For loss of nutrients, the doctor may prescribe fat-soluble vitamins A, D, and K. He or she may give vitamin B-12 injections monthly. The doctor may give medication to help severe diarrhea and vomiting.

How can I take care of myself?

To help take care of yourself, follow your doctor's instructions. Also, you should eat nutritious foods and try to maintain a healthy weight. If you suspect you are losing weight, weigh yourself once a month for three months. If you have lost more than 15 pounds without trying, you should consult your doctor. Give your doctor a record of everything you ate for three days.

What can be done to help prevent unexplained weight loss?

Call the doctor if you lose more than 20 pounds or 10% of your body weight when you're not trying to lose weight.