Patient Education
5-Hydroxyindoleacetic Acid Test
Why am I having this test?
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Help detect some types of tumors called carcinoid tumors. These are tumors that can start in any part of the body but especially in the stomach, intestines, or lungs.
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Monitor the treatment of carcinoid tumors.
What is being tested?
This is a 24-hour urine collection test that measures a product of serotonin called 5-HIAA. It is done to check the amount of 5-HIAA that your body is removing. High amounts of 5-HIAA may indicate the presence of disease.
What kind of sample is taken?
A urine sample is required for this test. The sample is collected in a germ-free (sterile) container that is given to you by the lab. You will use this container to collect all the urine you produce over 24 hours.
How do I do a 24-hour urine collection?
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When you get up in the morning, urinate in the toilet and flush. Write down the time. This will be your start time on the day of collection and your end time on the next morning.
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From the start time on, all of your urine should be kept in the collection jug that you received from the lab.
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If the jug that is given to you already has liquid in it, that is okay. Do not throw out the liquid or rinse out the jug. Some tests need the liquid to be added to your urine.
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Urinate into a specimen container, such as a urinal or pan that sits over the toilet. Pour the urine from the container into the collection jug. Be careful not to spill any of the urine. Use the equipment provided by the lab.
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Do not let any toilet paper or stool (feces) get into the jug. This will contaminate the sample.
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Stop collecting your urine 24 hours after you started. Collect the last specimen as close as possible to the end of the 24-hour period.
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Keep the jug cool in an ice chest or keep it in the refrigerator during collection.
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When the 24-hour collection is complete, bring the jug to the lab. Keep the jug cool in an ice chest while you are bringing it to the lab.
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Write your information on the label of the container. Use ink that will not smear. To do this:
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Write your full legal name. Do not write a nickname.
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Write your date of birth.
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Write the dates and times that you started and completed the sample.
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How do I prepare for this test?
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Do not eat foods that contain the hormone serotonin. This includes foods such as bananas, plantains, pineapple, kiwi, walnuts, plums, pecans, eggplant, tomatoes, and avocados. Also, do not eat these foods while taking the test.
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Do not drink alcohol.
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Do not take prescription and over-the-counter medicines that interfere with the test. Ask your health care provider about which medicines may interfere with the test and whether you need to change or stop your regular medicines.
How are the results reported?
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2–8 mg per 24-hour period, or 10–40 micromoles per day (SI units).
What do the results mean?
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The presence of a carcinoid tumor.
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Cystic fibrosis and other conditions that decrease the ability of your bowels to absorb food (intestinal malabsorption).
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Non-carcinoid illness.
If you already are being treated for a carcinoid tumor, an increased level of 5-HIAA may indicate that your treatment is not working.
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Depression.
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Migraine.
If you already are being treated for a carcinoid tumor, a decreased level of 5-HIAA may indicate that your treatment is working.
Talk with your health care provider about what your results mean.
Questions to ask your health care provider
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When will my results be ready?
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How will I get my results?
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What are my treatment options?
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What other tests do I need?
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What are my next steps?
Summary
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The 5-hydroxyindoleacetic acid (5-HIAA) test is used to detect carcinoid tumors and to monitor their treatment.
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This is a 24-hour urine collection test that measures a product of serotonin called 5-HIAA.
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Follow your health care provider’s instructions regarding foods and medicines to avoid before and during the test.
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High amounts of 5-HIAA may indicate the presence of disease.
This information is not intended to replace advice given to you by your health care provider. Make sure you discuss any questions you have with your health care provider.
