The medical term for decreased appetite is anorexia – this is a symptom, not a disorder. Anorexia is usually associated with involuntary weight loss.
Often, it is the weight loss and general malaise which trouble the patient more than the loss of appetite. Depending on the underlying cause of the decreased appetite, additional symptoms may be present, such as nausea, or pulse abnormalities (see under Causes).
Causes and associated disorders
Significant weight loss is loss of more than 5 percent of baseline weight over 6-12 months. When associated with decreased appetite, it is nearly always a sign of a serious medical or psychiatric condition. Some of the important causes are:
- Cancer – often the first sign of cancer is involuntary weight loss. This can progress to a wasting syndrome called cachexia. In some cases, the cancer directly causes decreased appetite by involving the intestines, for example causing pain on eating or difficulty swallowing.
- HIV infection often leads to decreased appetite.
- Hormone disturbances:
- Adrenal gland disorders,
- Hypercalcaemia of cancer patients, and
- Heart and lung disease, for instance congestive heart failure.
- Any chronic illness like kidney and liver disorders.
- Gastro-intestinal disease can cause pain, vomiting and other problems leading to decreased appetite.
- Psychiatric disorders: depression, manic-depression, Munchausen syndrome, delusional disorders, withdrawal of long-term medications, and eating disorders such as anorexia nervosa.
- Substance abuse involving long-term used of alcohol, opiates, nicotine and non-prescription medications.
- Prescription medication side-effects: includes
- Some anti-diabetic agents,
- Ant-cancer drugs, and
- Non-steroidal anti-inflammatories.
The diagnosis of anorexia is clinical. Clues to the underlying cause are usually found on examining the patient, and these will determine which special tests are needed. Useful tests include:
- Blood sugar levels and glucose tolerance tests;
- Thyroid function tests;
- Liver and kidney function tests;
- Full blood count for anaemia, infection, and dietary deficiencies; and
- X-rays or other studies, such as endoscopy or MRI of any body region thought to have cancer.
Underlying causes must be treated, and this may restore appetite to normal.
There are no really effective medications which exclusively stimulate appetite. Some medications used with limited success are:
- Megestrol acetate, and
- In cancer patients, steroids, and serotonin antagonists.
Much depends on the underlying cause. If this is treatable, the outcome is good. Anorexia associated with psychiatric disorders needs special treatment. Anorexia and weight loss associated with cancer is usually a bad sign, with a poor prognosis.
(Dr AG Hall, Health24)