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Biochemical Monitoring

To track your disease, your health care provider will use biochemical monitoring. Biochemical monitoring involves measuring the amount of certain body substances that are released by carcinoid tumors. The substances that are monitored on an ongoing basis are the same ones that are measured to diagnose carcinoid syndrome. On this page, you can learn more about the monitoring of these substances, which include:

It is very important that levels of these substances be checked regularly by your health care provider.

Chromogranin A (CgA) Testing

CgA is a protein found in carcinoid tumor cells. The protein may be released into the bloodstream. Therefore, CgA levels are measured by a blood test. The CgA test is considered an accurate test available both for detecting carcinoid tumors and for monitoring their activity.This includes carcinoid tumors that secrete certain hormones that are associated with carcinoid syndrome as well as carcinoid tumors that do not cause carcinoid syndrome. High levels of CgA are found in 80% to 100% of people with carcinoid syndrome.

Preparing for the CgA test

Your CgA level can be measured using a simple blood test. Your level will vary depending upon what you have eaten, so your health care provider will tell you to fast—that is, not to eat or drink anything for a certain number of hours—before you take the test.

How often to take the CgA test

Your health care provider will tell you how often to get a CgA test. Most people who are being treated for carcinoid syndrome need to have the test every 3 to 6 months.

What the results mean

The target number for your CgA test varies with the laboratory running the test. In general, though, if your numbers go down, it means your disease is under control. CgA levels that are very high (up to 1000 times normal levels) may indicate that carcinoid tumors have spread.

5-Hydroxyindoleacetic Acid (5-HIAA) Testing

5-HIAA—more specific to carcinoid syndrome than CgA—is a by-product that is produced when the body breaks down serotonin. Serotonin is one of the key body chemicals released by carcinoid tumors that are associated with carcinoid syndrome and plays a role in many of the signs and symptoms of carcinoid syndrome. The body gets rid of 5-HIAA in the urine. Therefore, 5-HIAA levels are measured in the urine. By measuring the level of 5-HIAA in the urine, health care providers can calculate the amount of serotonin in the body. The 5-HIAA test is the most common biochemical test for carcinoid syndrome.

Preparing for the 5-HIAA test

Certain foods have a high serotonin content, and eating them before a 5-HIAA test can increase your levels. Therefore, your health care provider will probably tell you not to eat the following foods for 24 hours before you take the test:

  • Bananas
  • Walnuts
  • Plantains
  • Hickory nuts
  • Pineapple
  • Pecans
  • Kiwi fruit
  • Avocados
  • Plums
  • Tomatoes
  • Eggplant

Several drugs can also affect the level of 5-HIAA in your urine, so your health care provider will probably tell you to avoid taking any of these drugs for 24 hours before you begin collecting urine for a 5-HIAA test.

Consult with your physician about which medications are appropriate to take before this test.

How often to take the 5-HIAA test

Your health care provider will tell you how often to get a 5-HIAA test. Most people who are being treated for carcinoid syndrome need to have the test every 3 to 6 months. The test is performed using urine samples collected during a 24-hour period.

What the results mean

In general, if your numbers go down, it means your disease is under control. Elevated 5-HIAA levels may indicate carcinoid heart disease.

Keeping Track of Your Levels

Keeping records of your CgA or 5-HIAA level (or both) over time can help you keep track of how well your treatment is working.