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By Mayo Clinic staffTell your doctor about your signs and symptoms. He or she will want to rule out other causes of flushing and diarrhea. If no other causes are found, your doctor may suspect carcinoid syndrome. To confirm your diagnosis, your doctor may recommend further tests, including:
- Urine test. Your urine may contain a certain substance made when your body breaks down serotonin. An excess amount of this substance could indicate that your body is processing extra serotonin, the chemical most commonly excreted by carcinoid tumors.
- Blood test. Your blood may contain high levels of the protein chromogranin A, which is released by some carcinoid tumors.
Your doctor may conduct other tests and imaging procedures to diagnose carcinoid syndrome. Imaging tests may also be used to locate the primary tumor and determine whether it has spread. Your doctor may start with a computerized tomography (CT) scan of your abdomen, because most carcinoid tumors are in the gastrointestinal tract. Other tests may be necessary.