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Carcinoid syndrome


This group of symptoms is typically associated with carcinoid tumor (see also Bronchial adenoma ).

Causes, incidence, and risk factors

Carcinoid syndrome is the pattern of symptoms which are exhibited by people with carcinoid tumors. These tumors can occur in the small intestine, colon, bronchial tubes, and appendix.

Carcinoid tumors secrete excessive amounts of the hormone serotonin as well as other chemicals that cause the blood vessels to dilate (widen). These tumors can also cause diarrhea and wheezing (asthma).

There are wide variations in the chemicals secreted by these tumors, and the symptoms depend on the mix of chemicals made by the particular tumor.

Normally, an amino acid, called tryptophan, is used by the body to manufacture niacin and certain proteins , but in carcinoid syndrome, it gets diverted to form serotonin. Most serotonin is converted by the body to 5-hydroxy indole acetic acid ( 5-HIAA ).

The most bothersome symptoms include bright red facial flushing , diarrhea (which may be explosive and severe) and occasionally wheezing . A specific type of heart valve damage can occur, as well as other cardiac problems.

In children, carcinoid tumors usually occur in the appendix, and removal of the appendix usually results in a complete cure.


  • Abdominal pain , intermittent
  • Flushing
  • Diarrhea
  • Wheezing
  • Heart palpitations
  • Low blood pressure

Signs and tests

  • 5-HIAA levels in urine are elevated in 75% of cases. Certain foods and medicines must be avoided for a day or two before this test, and on the day the urine is collected. These include bananas, pineapple and its juice, red plums, avocado, walnuts, kiwi fruit, tomatoes, various cough medicines, muscle relaxing medicines, acetaminophen (Tylenol), caffeine, fluorouacil, iodine solutions, phenacetin, MAO inhibitors (certain anti-depressant drugs), isoniazid, and phenothiazine drugs (Compazine, Thorazine).
  • Serotonin levels in blood may be elevated.
  • Chromogranin A in blood may be elevated.
  • Tryptophan in blood may be decreased.
  • The OctreoScan -- a radio-isotope scanning test -- has been approved by the U.S. Food and Drug Administration. This test will identify most carcinoids and any other neuroendocrine tumors.
  • A CT and MRI scan may be done along with the OctreoScan to monitor the progress of treatment of the carcinoid tumor.
  • Less frequent tests may include histamine, bradykinin, neurone-specific enolase, calcitonin, Substance-P, neurokinin-A, and pancreatic polypeptide.

An examination may indicate heart valve lesions or signs of niacin-deficiency disease ( pellagra ). Signs of pellagra develop when most of the available tryptophan is used by the tumor to produce serotonin , which then prevents the body from manufacturing niacin .


Surgery with complete removal of the tumor tissue is usually the first line treatment. It can result in permanent cure if it is possible to remove the tumor entirely.

Even when the entire tumor cannot be removed, removing large portions of the tumor (debulking) can effectively relieve the symptoms by decreasing the amount of harmful hormones being produced and flooding the circulation.

There are also some new procedures for treating tumors that have spread or metastasized to the liver.

The mainstay of treatment for advanced carcinoid tumors that cannot be removed surgically is Sandostatin (octreotide) injections. In many cases, this anti-hormone drug inhibits and sometimes reverses the growth of the tumors.

This is given by injection 2-3 times per day, and then the injection may be changed to once a month using a long acting release (LAR) dosage after a 2-4 week period. This often improves symptoms of the carcinoid syndrome, and decreases tumor progression.

Interferon is another drug often given with octreotide. It is referred to as an immuno modulator. Its effect is to suppress or stop the growth of the tumor.

Chemotherapy can be given by intravenous injection or by mouth for carcinoid syndrome. Many combinations have been used. If one combination is ineffective, another combination may be effective, and overall about one-third of patients benefit from chemotherapy.

Increased protein and a low-fat diet are often recommended. Multivitamin mineral and low dose nicotinic acid (niacin) supplements may be prescribed. Other items sometimes recommended are fish oil capsules, electrolyte supplements, and in some cases, large portions of nutmeg. Avoid ingestion of alcohol, large meals, and foods high in tyramine, as these may provoke symptoms.

A serotonin antagonist may be prescribed to control diarrhea and inadequate absorption of nutrients from the intestines ( malabsorption ).

Sandostatin and similar medications may be effective in reducing the episodes of flushing and diarrhea and in reversing the blood pressure changes. There are other medications that may be prescribed for symptoms as well.

Some common medicines, like selective serotonin reuptake inhibitors (SSRIs, such as Paxil, Serzone, and Prozac) may make symptoms worse by increasing levels of serotonin. However, these medicines should be discontinued only on the advice of your doctor, since stopping them abruptly may cause withdrawal symptoms and since depression can cause health problems as well.

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Last updated: Tue, 06 Jan 2009 00:20:03 GMT