At a Glance
Why Get Tested?
When to Get Tested?
When you have symptoms of increased catecholamines release, such as persistent or episodic high blood pressure, severe headaches, rapid heart rate, and sweating
Test Preparation Needed?
Foods such as coffee (including decaf), tea, chocolate, vanilla, bananas, oranges and other citrus fruits should be avoided for several days prior to the test and during collection. There are also many medications that can potentially affect test results. Talk to your doctor about any prescriptions and over-the-counter drugs and supplements that you are taking. Wherever possible, those that are known to interfere should be discontinued prior to and during sample collection. Emotional and physical stresses and vigorous exercise should be minimized prior to and during test collection as they can increase catecholamines secretion.
The Test Sample
What is being tested?
This test measures the amounts of metanephrine and normetanephrine that are excreted in the urine over a 24-hour period. Metanephrine and normetanephrine are the inactive metabolites of the catecholamines epinephrine (adrenaline) and norepinephrine. Catecholamines are a group of similar hormones produced in the medulla (central portion) of the adrenal glands. The adrenal gland is a small, triangular organ located on top of each kidney.
The primary catecholamines are dopamine, epinephrine (adrenaline), and norepinephrine. These hormones are released into the bloodstream in response to physical or emotional stress. They help transmit nerve impulses in the brain, increase glucose and fatty acid release for energy, dilate small air passages in the lungs called bronchioles, and dilate the pupils. Norepinephrine also constricts blood vessels, which increases blood pressure, and epinephrine increases heart rate and metabolism. After completing their actions, the catecholamines are metabolized to form inactive compounds. Dopamine becomes homovanillic acid (HVA), norepinephrine breaks down into normetanephrine and vanillylmandelic acid (VMA), and epinephrine becomes metanephrine and VMA. Both the hormones and their metabolites are excreted in the urine.
Urine metanephrines testing measures the amount of both metanephrine and normetanephrine. These metabolites are usually present in the urine in small fluctuating amounts that increase appreciably during and shortly after the body is exposed to a stressor. Rare pheochromocytomas and other neuroendocrine tumors, however, can produce large amounts of catecholamines, resulting in greatly increased concentrations of the hormones and their metabolites in both the blood and urine. The catecholamines that a pheochromocytoma produces can cause persistent hypertension (high blood pressure) and episodes of severe hypertension. Other symptoms of catecholamine release include headaches, palpitations, sweating, nausea, anxiety, and tingling in the extremities.
About 90% of pheochromocytomas are located in the adrenal glands. While a few are cancerous, most are benign – they do not spread beyond their original location – although most do continue to grow. Left untreated, the symptoms may worsen as the tumor grows and, over a period of time, the hypertension from a pheochromocytoma may cause kidney damage, heart disease, and raise the risk of a stroke or heart attack.
The metanephrines test can be used to help detect the presence of pheochromocytomas. Although, according to the National Cancer Institute, only about 800 cases a year are diagnosed in the U.S., it is important to diagnose and treat these rare tumors because they cause a potentially curable form of hypertension. In most cases, the tumors can be surgically removed and/or treated to significantly reduce the amount of catecholamines being produced and to reduce or eliminate associated symptoms and complications.
How is the sample collected for testing?
For the 24-hour urine collection, all urine should be saved for a 24-hour period. It is important that the sample be refrigerated during this time period.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
Foods such as coffee (including decaf), tea, chocolate, vanilla, bananas, oranges and other citrus fruits should be avoided for several days prior to the test and during collection. There are also many medications that can potentially affect test results. People being tested should talk to their doctor about prescriptions and over-the-counter drugs and supplements that they are taking. Wherever possible, substances that are known to interfere should be discontinued prior to and during sample collection. However, it is important to consult with the doctor before stopping any medications. Emotional and physical stresses and vigorous exercise should be minimized prior to and during sample collection as they can increase catecholamines secretion.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby’s Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 1023-1026.
(Reviewed 2011 January). Pheochromocytoma. American Urological Association AUA Foundation [On-line information]. Available online at http://www.urologyhealth.org/urology/index.cfm?article=14 through http://www.urologyhealth.org. Accessed December 2011.
(© 1995-2011). Test ID: METAR83005, Metanephrines, Fractionated, Random, Urine. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/83005 through http://www.mayomedicallaboratories.com. Accessed December 2011.
Blake, M. and Sweeney, A. (Updated 2011 October 19). Pheochromocytoma. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/124059-overview through http://emedicine.medscape.com. Accessed December 2011.
Frank, E. et. al. (Updated 2011 June). Pheochromocytoma. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Pheochromocytoma.html?client_ID=LTD through http://www.arupconsult.com. Accessed December 2011.
Sources Used in Previous Reviews
Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].
Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.
Sawka, A., et. al. (2003 February). A Comparison of Biochemical Tests for Pheochromocytoma: Measurement of Fractionated Plasma Metanephrines Compared with the Combination of 24-Hour Urinary Metanephrines and Catecholamines. The Journal of Clinical Endocrinology & Metabolism Vol. 88, No. 2 553-558 [On-line journal]. Available online at http://jcem.endojournals.org/cgi/content/full/88/2/553 through http://jcem.endojournals.org.
Brose, M. Updated (2004 August 3, Updated). Pheochromocytoma. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000340.htm.
(© 2005). Metanephrines, Plasma. ARUP's Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_a76b.jsp#2461156 through http://www.aruplab.com.
(© 2005). Metanephrines, Urine. ARUP's Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.aruplab.com/guides/clt/tests/clt_a77b.jsp#1141889 through http://www.aruplab.com.
(© 1995-2005). Pheochromocytoma. The Merck Manual of Diagnosis and Therapy, Section 2. Endocrine And Metabolic Disorders, Chapter 9. Adrenal Disorders [On-line information]. Available online at http://www.merck.com/mrkshared/mmanual/section2/chapter9/9d.jsp through http://www.merck.com.
Vogin, G. Reviewed (2002). Plasma Metanephrines Best to Diagnose Pheochromocytoma. Medscape Medical News [On-line news article]. Available online at http://www.medscape.com/viewarticle/430266?src=search through http://www.medscape.com.
Schwartz, G. and Sheps, S. (2004 May 06). Hypertension. MedScape Today from ACP Medicine [On-line information]. Available online at http://www.medscape.com/viewarticle/474790?src=search through http://www.medscape.com.
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Pagana, Kathleen D. & Pagana, Timothy J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference. 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 987-990.
Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry. AACC Press, Washington, DC. Pp 382-383.
Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 724-731.
Pacak, K. et. al. (2007 March 21). Pheochromocytoma: Recommendations for Clinical Practice from the First International Symposium. Medscape from Nat Clin Pract Endocrinol Metab. 2007;3(2):92-102. [On-line information]. Available online at http://www.medscape.com/viewarticle/553428 through http://www.medscape.com. Accessed on 9/29/08.
Sweeney, A. et. al. (2007 September 11, Updated). Pheochromocytoma. EMedicine [On-line information]. Available online at http://www.emedicine.com/med/TOPIC1816.HTM through http://www.emedicine.com. Accessed on 9/29/08.
Vilar, L. (2008 June 17). Adrenal Incidentalomas: Diagnostic Evaluation and Long-Term Follow-up. Medscape from Endocr Pract. 2008;14(3):269-278 [On-line information]. Available online at http://www.medscape.com/viewarticle/574415 through http://www.medscape.com. Accessed on 9/29/08.
(2007 December). Pheochromocytoma. UrologyHealth.org [On-line information]. Available online at http://urologyhealth.org/adult/index.cfm?cat=02&topic=114 through http://urologyhealth.org. Accessed on 9/29/08.
Grossman, A. (2007 November Reviewed). Pheochromocytoma. Merck Manual for Professionals [On-line information]. Available online at http://www.merck.com/mmpe/print/sec12/ch153/ch153h.html through http://www.merck.com. Accessed on 9/29/08.