Carcinoid Syndrome and the Benefits of the 5-Hydroxyindoleacetic Acid Test

Carcinoid Syndrome is a disease that can go undiagnosed for some time as the symptoms may not be noticed until the tumors have spread to the liver. Unfortunately, the problem with this is a Carcinoid tumor is a slow-growing tumor and is often malignant.

You may visit your doctor because you are suffering from flushing, diarrhea, wheezing, abdominal cramping and peripheral edema (the swelling of tissue usually in the lower limbs). These are all symptoms that could give a clue that you might be suffering from Carcinoid Syndrome, but these symptoms all present themselves in other and less chronic medical issues, and therefore, a correct diagnosis can be missed.

If it is suspected that you may be suffering from Carcinoid Syndrome it is probable that your Doctor will run a test known as a 5-Hydroxyindoleacetic acid (5-HIAA) test. Which is simply a 24 hour urine collection and is certainly not painful just a little inconvenient.

Carcinoid tumors contain argentaffin staining (enter endocrine) cells which means that they produce serotonin and other powerful neuro-hormones that are metabolized by the liver to 5-HIAA and are excreted in the urine. Therefore a quantitive analysis of urine levels can detect the presence of Carcinoid tumors.

Once it has been decided that you require a 5-HIAA you will be required to have 3-4 preparation days before taking the 24 hour urine collection. The prep days aren't too horrendous it just means that during these days you need to refrain from eating or drinking anything that could interfere with the test. You will need to avoid things which contain serotonin such as plums, pineapples, bananas, eggplant, tomatoes, avocadoes, walnuts, kiwi fruits and pecans (your Doctor will give you the full list).

On the day of the collection (try and aim for a day when you can stay home..) you will need to discard the first output of urine and then start timing and collecting. Collect all urine for the next 24 hours and store the container either on ice or in a refrigerator (the main thing is to keep the collection cool). Be sure to collect the last sample as close to the end of the 24 hours as possible.

Once you have done your part return the container to the Doctor who will label it listing on the laboratory slip any medications that may affect the test results. There are certain drugs which can cause increased or decreased 5-HIAA levels.

The 5-Hydroxyindoleacetic Acid test is not only useful in diagnosing Carcinoid Syndrome but it is also relevant in re-evaluating patients with known Carcinoid tumors by using serial levels of 5-HIAA. Should a patient show rising levels of 5-HIAA it would indicate a progression of the tumor whereas falling levels of 5-HIAA will indicate a therapeutic response of the tumor to antineoplastic therapy.

Source:
Mosby's Diagnostic and laboratory test Reference by Pagana and Pagana