Plasma Free Metanephrines
- Also Known As:
- Plasma Metanephrines
- Formal Name:
- Fractionated Plasma Free Metanephrines (Metanephrine and Normetanephrine)

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At a Glance
Why Get Tested?
To help diagnose or rule out a rare tumor of the adrenal gland called a pheochromocytoma or a rare tumor occurring outside the adrenal glands called a paraganglioma; these tumors (PPGL) produce excess hormones called catecholamines, which are broken down to metanephrines.
When To Get Tested?
When your healthcare provider either suspects that you have a tumor that produces catecholamines or wants to rule out the possibility; when you (especially if you are younger than age 40) have sudden bursts (paroxysms) of signs and symptoms, such as high blood pressure (especially if it doesn’t respond to standard treatment), severe headaches, rapid heart rate (palpitations), sweating, tremors and flushing; when you have a hereditary (genetic) risk for developing PPGL; when a tumor has been treated or removed, to monitor for recurrence; occasionally, when an adrenal tumor is detected by chance, such as during an imaging test for another condition
Sample Required?
A blood sample drawn from a vein
Test Preparation Needed?
Blood for plasma metanephrine testing is collected by inserting a needle into a vein in your arm. Although you may be seated for the collection, it is recommended that you be lying down. The health care practitioner or the collection site will instruct you as to their specific requirements.
These tests are affected by certain drugs, foods, and stresses. Inform your healthcare practitioner of any medications you are taking and follow any preparation instructions you are given before sample collection.
You may be able to find your test results on your laboratory’s website or patient portal. However, you are currently at Testing.com. You may have been directed here by your lab’s website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab’s website or portal, or contact your healthcare practitioner in order to obtain your test results.
Testing.com is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.
The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.
If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.
Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.
While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”
For more information, please read the article Reference Ranges and What They Mean.
What is being tested?
The metanephrines – metanephrine and normetanephrine – are breakdown products (metabolites) of the catecholamines epinephrine (adrenaline) and norepinephrine. The plasma free metanephrines test measures the amount of metanephrine and normetanephrine in the blood.
Catecholamines are produced by the adrenal glands (as hormones), small triangular organs located on top of each kidney, and by cells of the sympathetic nervous system (called neurotransmitter substances or neurotransmitters). The primary catecholamines are dopamine, epinephrine (adrenaline), and norepinephrine. Catecholamines are released 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 the rate at which the body uses energy (metabolism).
After completing their actions, catecholamines are metabolized to inactive compounds. Epinephrine breaks down into metanephrine and vanillylmandelic acid (VMA) and norepinephrine becomes normetanephrine and VMA. Both the hormones and their metabolites are eliminated from the body in the urine.
Catecholamines and their breakdown products are normally found in small fluctuating quantities in the blood and urine and only increase appreciably during and shortly after a stressful situation.
However, rare tumors of the adrenal glands called pheochromocytomas and rare tumors that occur outside the adrenal glands called paragangliomas can produce large amounts of the hormones, resulting in significantly increased concentrations in both the blood and urine. (These syndromes are often grouped together and abbreviated as PPGL.) This can cause persistent or episodic periods of high blood pressure, which may lead to severe headaches. Other symptoms include palpitations, sweating, nausea, anxiety, and tingling in the hands and feet.
Pheochromocytomas and paragangliomas are rare. While a few are cancerous, most are benign and do not spread beyond their original location. Left untreated, however, these tumors may continue to grow and the symptoms may worsen. Over time, hypertension caused by the excess hormones may cause kidney damage, heart disease, and raise the risk of a stroke or heart attack.
Although they are rare, it is important to diagnose these tumors because they cause a potentially curable form of hypertension. In most cases, the tumors can be surgically removed and/or treated to eliminate or significantly reduce the amount of catecholamine being produced and to eliminate their associated symptoms and complications.
How is the sample collected for testing?
Blood for plasma free metanephrines testing is collected by inserting a needle into a vein in the arm. Although you may be seated for the collection, it is recommended that you be lying down. Your healthcare practitioner or the collection site will instruct you as to their specific requirements.
Is any test preparation needed to ensure the quality of the sample?
Catecholamine levels and by extension the levels of their metabolites are affected by various drugs, foods, and stresses. Preparation for the test is important to ensure that an appropriate sample is collected and for correct interpretation of results. Follow any instructions given by your health care practitioner or the collection site or laboratory.
- You should talk to your health care provider about any prescription medications and over-the-counter drugs and supplements that you are taking. It may be necessary to discontinue medications for some time prior to the test.
- However, you should not stop taking any medications without consulting your healthcare provider. Your health practitioner will work with you to identify potentially interfering substances and drug treatments and to determine which of them can be safely interrupted and which must be continued for your well-being.
- You will also be instructed on what foods to avoid. Fasting may also be required prior to the sample being drawn.
- Avoid emotional and physical stresses and vigorous exercise prior to and during sample collection as they can increase catecholamine release and therefore affect metanephrine levels.
Common Questions
View Sources
Sources Used in Current Review
2019 review performed by Ghaith Altawallbeh, PhD, Clinical Chemistry Fellow.
(August 10, 2018) Blake, MA. Pheochromocytoma Workup, Medscape. Available online at https://emedicine.medscape.com/article/124059-workup. Accessed on 07/05/19.
Lenders JWM and Eisenhofer G (2017). Update on modern management of pheochromocytoma and paraganglioma. Endocrinol Metab (Seoul) 32:152–161. Available online at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5503859/. Accessed on 07/05/19.
Metanephrines, Fractioned, Free, Plasma. Mayo Medical Laboratories. Available online at https://www.mayomedicallaboratories.com/test-catalog.org/show/PMET. Accessed on 07/05/19.
(January 4, 2018) Pacak K, Tella SH. Pheochromocytoma and Paraganglioma. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available online at https://www.ncbi.nlm.nih.gov/books/NBK481899/. Accessed on 07/05/19.
Sources Used for 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. Pp (900-903).
(© 2004). 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.
(© 2004). Metanephrines, Plasma. ARUP’s User’s Guide [On-line test information]. Available online at http://www.aruplab.com/guides/ug/tests/0050184.jsp.
Eisenhofer, G. et. al. (© 2003). Biochemical Diagnosis of Pheochromocytoma: How to Distinguish True- from False-Positive Test Results. The Journal of Clinical Endocrinology & Metabolism Vol. 88, No. 6 2656-2666 [On-line journal]. Available online at http://jcem.endojournals.org/cgi/content/full/88/6/2656.
Yogish, C. (2003 October). The Laboratory Diagnosis of Adrenal Pheochromocytoma: The Mayo Clinic Experience. The Journal of Clinical Endocrinology & Metabolism Vol. 88, No. 10 4533-4539 [On-line journal]. Available online at http://jcem.endojournals.org/cgi/content/full/88/10/4533.
(1999 June 16). Researchers Develop Better Means to Diagnose Adrenal Gland Tumors. NIH News Release [On-line press release]. Available online at http://www.nih.gov/news/pr/jun99/ninds-16.htm.
Sadovsky, R. (2003 September 15). Management of the Clinically Inapparent Adrenal Mass. American Family Physician, Tips from Other Journals [On-line journal]. Available online at http://www.aafp.org/afp/20030915/tips/9.html.
(2003 December 18). Pheochromocytoma (PDQ®): Treatment, Health Professional Version. National Cancer Institute [On-line information]. Available online at http://www.cancer.gov/cancertopics/pdq/treatment/pheochromocytoma/HealthProfessional.
Howard, S. (2002 August 29). heochromocytoma. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000340.htm.
(2002 September). Pheochromocytoma. NIH, Warren Grant Magnuson Clinical Center, Patient Information Publications [On-line information]. PDF available for download at http://www.cc.nih.gov/ccc/patient_education/pepubs/pheo.pdf.
Schwartz, G. and Sheps, S. (2004 May 6). Hypertension. Medscape from ACP Medicine 2004. © 2004 WebMD Inc. [On-line article]. Available online at http://www.medscape.com/viewarticle/474790.
(© 2004). Pheochromocytoma. The Merck Manual Second Home Edition [On-line information]. Available online at http://www.merck.com/mmhe/sec13/ch164/ch164f.html.
Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 728-279.
(2008 June 18, Modified). Pheochromocytoma Treatment, Patient Version. National Cancer Institute [On-line information]. Available online at http://www.cancer.gov/cancertopics/pdq/treatment/pheochromocytoma/patient/allpages. Accessed on 7-28-08.
(2007 April 17, Updated). Pheochromocytoma. National Institute of Child Health and Human Development [On-line information]. Available online at http://www.nichd.nih.gov/health/topics/pheochromocytoma.cfm. Accessed on 7-27-08.
Nanda, R. (2006 September 11, Update). Pheochromocytoma. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000340.htm. Accessed on 7-28-08.
Sweeney, A. et. al. (2007 September 11, Updated). Pheochromocytoma. eMedicine [On-line information]. Available online at http://www.emedicine.com/med/TOPIC1816.HTM. Accessed on 7-28-08.
(© 2006-2008). Pheochromocytoma. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/OncologicDz/NeuroendocrineTumors/Pheochromocytoma.html. Accessed on 7-28-08.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby’s Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 673-675.
Vuguin, P. M. (Updated 2011 October 4). Pediatric Pheochromocytoma. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/988683-overview. Accessed December 2011.
(Reviewed 2011 January). Pheochromocytoma. American Urological Association AUA Foundation [On-line information]. Available online at http://www.urologyhealth.org/urology/index.cfm?article=14. 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. 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. Accessed December 2011.
Blake, M. and Sweeney, A. (2014 June 16, Updated). Pheochromocytoma. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/124059-overview. Accessed on 4/25/15.
Vuguin, P. (2013 June 27 Updated). Pediatric Pheochromocytoma. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/988683-overview. Accessed 04/25/15.
Baldwin, E. et. al. (2015 April, Updated). Pheochromocytoma. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Pheochromocytoma.html?client_ID=LTD. Accessed 4/25/15.
(© 1995–2015). Metanephrines, Fractionated, Free, Plasma. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/81609. Accessed 04/25/15.
(2015 April 10, Updated). Unusual Cancers of Childhood Treatment (PDQ®). National Cancer Institute [On-line information]. Available online at http://www.cancer.gov/cancertopics/pdq/treatment/unusual-cancers-childhood/Patient/page7. Accessed 04/25/15.
Pagana, K. D., Pagana, T. J., and Pagana, T. N. (© 2015). Mosby’s Diagnostic & Laboratory Test Reference 12th Edition: Mosby, Inc., Saint Louis, MO. Pp 636-637.
National Cancer Institute: PDQ® Pheochromocytoma and Paraganglioma Treatment. Bethesda, MD: National Cancer Institute. Date last modified 04/30/2015. Available online at http://www.cancer.gov/types/pheochromocytoma/hp/pheochromocytoma-treatment-pdq. Accessed 07/21/2105.
Lenders, J.W.M. et al. Guidelines on Pheochromocytoma and Paraganglioma. J Clin Endocrinol Metab, June 2014, 99(6): 1915-42
Eisenhofer, G. and Peitzch, M. Laboratory Evaluation of Pheochromocytoma and Paraganglioma. Clinical Chemistry, 2014, 60(12) 1486–1499.
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