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Paraganglioma (adrenaline-producing tumor outside the adrenal gland)

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Diagnosis and Radiological Tests

Biochemical Tests

In patients who are thought to have a paragangliomaParaganglioma - a disease where too much adrenaline is being made by a tumor outside the adrenal glands, biochemical tests should be done to measure the levels of catecholamines (adrenalineAdrenaline - the hormone that helps control the "fight or flight" response and puts the body on "high alert" (also known as epinephrine), noradrenaline, and dopamine) and metanephrines (i.e. the molecules that catecholamines break down into). The reason that many physicians rely on the metanephrines levels more than the catecholamine levels is that adrenaline only lasts a short time in the body before it is broken down, while metanephrines last much longer in the body. Catecholamine and metanephrines levels may be measured in either the plasma (i.e. blood) or in a 24 hour urine collection. It is not clear if the urine test or the blood test is "better" so you should work with your physician to determine which is better for you. In general, plasma tests are better for children with whom a 24 hour urine collection is not possible. In addition, plasma metanephrines is a very sensitive study (i.e. identifies all patients with the disease, but may have false positives—i.e. positive test in someone who does not have a paraganglioma) and is therefore good for patients with known disease and for patients with a known family history of pheochromocytomaPheochromocytoma - a disease where too much adrenaline is being made by an adrenal tumor/paraganglioma or associated genetic syndromes. Although the National Institute of Health recommends plasma metanephrines for patients with an incidentally discovered adrenal tumor, many physicians feel that the 24 hour urine test is better than the plasma test because it has fewer false positives. Levels that are at least twice the upper limit of normal levels confirm that the patient has a paraganglioma. Certain medications and certain conditions can lead to false positive results (i.e. a positive test in someone who does not have pheochromocytoma:

Check with your doctor before being tested and be sure he or she knows all of your medications. Other available tests include suppression and provocative testing that are rarely, if ever, needed. Provocative tests can cause life-threatening high blood pressure. The diagnosis of a paraganglioma should be suspected in any patient in whom imaging reveals a tumor that is next to the vertebral region of the abdomen or adjacent to the aorta.

Radiological Tests

Paraganglioma (adrenaline-producing tumor outside the adrenal gland) On CAT scan
Figure 13: Paraganglioma On CAT scan

When the diagnosis is confirmed with plasma or urine studies, the patient should have a CAT scan or MRI to identify the location of the paraganglioma. Paragangliomas usually have a very distinct appearance on CAT scan and MRI. Since patients can have multiple paragangliomas, it is typically recommended to use a number of tests to localize the disease, especially in cases of familial paraganglioma syndrome. Nuclear medicine tests like an MIBG scan (i.e. metaiodobenzylguanidine scan) or PET scan (i.e. positron emission tomography scan) can be helpful. These tests use a weakly radioactive particle to home into the tumor so that it "lights up" on X-ray. The MIBG scan is specific for adrenaline-producing tumors while the PET scan identifies any very metabolically active tumors. There are many types of PET scans available for pheochromocytoma and paraganglioma including 18Fluoro-2-deoxy-glucose (18F-FDG PET-CT) or 18Fluorodopamine (18F DOPA-PET). In one recent study of 52 patients with paragangliomas, all were localized by imaging with CAT scan and /or MRI. Of the functioning imaging studies, 18F-FDG PET-CT provided the greatest sensitivity for identifying paragangliomas (88% sensitivity).12

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