Diagnosing Carcinoid Tumors

The early stages of carcinoid syndrome are difficult to diagnose for various reasons. Most symptoms are quite common and wide-ranging. For example, flushing can be a symptom of carcinoid syndrome but it may also be indicative of menopause, an alcoholic reaction, or an aftereffect of the drug, which can make differential diagnosis difficult.

Diagnosing Procedure for Carcinoid Tumors

Physical checkup and medical history: The doctor will inquire about lifestyle, general health, symptoms, and risk factors. Patients may be asked to describe the symptoms of carcinoid syndrome and a tumor in intestines, stomach, or rectum. Benign or cancerous tumors of other organs can also be found in the patients who have neuroendocrine tumors.

Barium X-ray: In this test, the lining of the esophagus, abdomen, and intestines is coated with a barium solution. By examining the barium lining, abnormalities of these organs can be detected. Gastrointestinal (GI) carcinoid tumors are diagnosed using this method.

Upper GI series: The upper part of the small intestine and the lining of the stomach are examined using this test. When a patient consumes the solution, barium coats the lining of the stomach. The upper part of the small intestine is coated once coating of the stomach is finished. For the next few hours, barium travels through the small intestine, helping the physician to take more X-rays.

Tumor marker test: Chromogranin A produced by organs, tumor cells, and tissues is a tumor marker in higher concentration and is measured to quantify its amount by testing the sample of urine, blood, and tissue.

Twenty-four-hour urine test: To test 5-hydroxyindoleacetic acid (5-HIAA) or serotonin (hormone), urine is collected for 24 hours. Abnormal levels of the hormones can be a sign of the disease and used as a diagnostic tool for carcinoid.

MIBG scan: In this test, a mild dosage of a radioactive element called metaiodobenzylguanidine (MIBG) is injected into the bloodstream. These radioactive elements affect carcinoid tumors and are treated by a radiation device.

CT scan (CAT scan): Accurate pictures of internal body areas are taken from different angles using this procedure. The X-ray machine is linked with a computer to take pictures. For this procedure, patients might be asked to consume or be injected with a dye into the vein for viewing the tissues or organs more clearly. This procedure is also known as computerized axial/computed/computerized tomography.

MRI (magnetic resonance imaging): A sequence of accurate pictures of internal body areas is taken by using a magnet, a computer, and radio waves in this procedure.

PET (positron emission tomography) scan: Malignant tumor cells in the body can be found with the help of this method. It involves injection of radioactive glucose or sugar and a PET scanner, which rotates around the body and takes photos of specific parts of the body where glucose is absorbed. The normal cells absorb less radioactive glucose than malignant tumor cells, which are proactive and appear more intensely.

Endoscopic ultrasound (EUS): An endoscope is inserted through the mouth or rectum into the body in this procedure. A thin, tube-like instrument with a lens and a light for the spot is known as an endoscope. The ultrasound waves (high-energy sound waves) reflected by organs such as the small intestine, colon or rectum, stomach, and internal tissues are sensed and echoes are made by a probe at the end of the endoscope. A sonogram is a picture of the body tissues that are formed from the echoes. This method is also termed as endosonography.

Capsule: In this method, the patient is asked to consume a capsule that contains a tiny camera. This is able to capture images as it moves through the GI tract and sends them to the external receiver so that the entire small intestine can be viewed.

Double balloon enteroscopy: The small intestine is too long (20 feet) to examine with regular endoscopy; moreover, it has too many curves, which makes examination even more difficult. In this method, a special endoscope made up of two tubes, one over the other, is used to overcome this issue.

Blood and urine tests: Carcinoid syndrome can be diagnosed by testing the blood and urine of patients. 5-HT or serotonin compounds are formed by the carcinoid tumors which are found in the small intestine and cause symptoms of carcinoid syndrome. 5-HIAA breaks down and discharges in urine.

Urine samples are collected for 24 h and a common test to examine the carcinoid syndrome is to measure 5-HIAA levels. Measuring the level of serotonin in the blood can be very useful. Normal serotonin levels in the blood with high serotonin and 5-HTP levels in urine are found in patients with these types of tumors. The doctor may prescribe other blood tests depending on the symptoms and the tumor-affected area.

Reviewed by Yolanda Smith, BPharm

Further Reading

Last Updated: Sep 12, 2017

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