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By Mayo Clinic staffTests and procedures used to diagnose carcinoid tumors include:
- Blood test. If you have a carcinoid tumor, your blood may contain high levels of a protein caused by hormones secreted by a carcinoid tumor.
- Urine test. People with carcinoid tumors have excess levels of a chemical in their urine that's produced when the body breaks down hormones secreted by carcinoid tumors.
- Imaging tests. Imaging tests, including a computerized tomography (CT) scan, magnetic resonance imaging (MRI), positron emission tomography (PET), ultrasound, octreotide scan and X-ray, may help your doctor pinpoint the carcinoid tumor's location.
- Using a scope or camera to see inside your body. Your doctor may use a long, thin tube equipped with a lens or camera to examine areas inside your body. An endoscopy, which involves passing a scope down your throat, may help your doctor see inside your gastrointestinal tract. Bronchoscopy, using a scope passed down your throat and into your lungs, can help find lung carcinoid tumors. Passing a scope through your rectum (colonoscopy) can help diagnose rectal carcinoid tumors. To see inside your small intestine, your doctor may recommend a test using a pill-sized camera that you swallow (capsule endoscopy).
- Biopsy. A sample of tissue from the tumor (biopsy) may be collected to confirm your diagnosis. What type of biopsy you'll undergo depends on where your tumor is located. In some cases a surgeon may use a needle to draw cells out of the tumor. In other cases, a biopsy may be collected during surgery. The tissue is sent to a laboratory for testing to determine the types of cells in the tumor and how aggressive those cells appear under the microscope.