Also Known As
Plasma Metanephrines
Formal Name
Fractionated Plasma Free Metanephrines (Metanephrine and Normetanephrine)
This article was last reviewed on
This article waslast modified on February 18, 2020.
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 healthcare 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 Lab Tests Online. 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.

Lab Tests Online 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 hypertension, 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 healthcare practitioner or the collection site or laboratory.

  • You should talk to your healthcare 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 healthcare 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.
See More
See Less
Common Questions
  • How is it used?

    The plasma free metanephrines test is used to help diagnose or rule out the presence of a rare tumor called a pheochromocytoma or a paraganglioma (PPGL) that releases excess metanephrines. Testing also may be used when a tumor has been treated or removed to monitor for recurrence.

    The Endocrine Society, the American Association for Clinical Chemistry, and the European Society of Endocrinology have released clinical practice guidelines for the diagnosis and management of pheochromocytoma and paraganglioma. The guidelines recommend using a test for plasma free metanephrines or urine metanephrines to evaluate an individual for PPGL.

    • The blood test may be most useful when you have persistent hypertension or are currently experiencing a sudden burst (paroxysm) of hypertension. This is because the hormones do not stay long in the blood; they are used by the body and rapidly broken down (metabolized) and/or then eliminated.
    • Urine testing measures the total amount of metanephrines released into the urine in 24 hours. Since the hormone levels may fluctuate significantly during this period, the urine test may detect excess production that is missed with a blood test.

    However, your healthcare practitioner may select any one (or more than one) of these tests depending on your signs and symptoms, family history, and/or genetic profile.

  • When is it ordered?

    The plasma free metanephrines test is primarily ordered when your healthcare practitioner either suspects that you have a tumor that produces catecholamines or wants to rule out the possibility. It may be ordered when you (especially if you are younger than age 40) have sudden bursts (paroxysms) of signs and symptoms, such as:

    • High blood pressure (hypertension), especially when you have hypertension that is not responding to treatment (people with these tumors are frequently resistant to standard therapies)
    • Severe headaches
    • Excessive sweating
    • Flushing
    • Rapid heart rate (palpitations)
    • Tremor

    Testing may also be ordered when a tumor that releases catecholamines has been treated or removed to monitor for recurrence.

    Occasionally, the test may be ordered when an adrenal tumor is detected incidentally, such as during a scan conducted for another purpose, or when you have an inherited (genetic) risk or family history of pheochromocytomas.

  • What does the test result mean?

    Normal metanephrine and normetanephrine blood levels mean it is unlikely that you have a tumor that produces catecholamines. The plasma free metanephrines test is very sensitive and these tumors are rare, making it the best test for excluding PPGL.

    High levels of metanephrine and normetanephrine when you have signs and symptoms suggest the presence of a tumor. It is recommended that patients with a positive result receive appropriate follow-up according to the test values noted and the clinical presentation. Imaging scans, such as MRI, should be done to locate the tumor.

    If levels are elevated after you have been treated for one of these tumors, it may be an indication that the treatment was not fully effective or that the tumor is recurring and appropriate follow-up is needed.

    The test for metanephrines is very sensitive and false positives do occur. The test is affected by stress, drugs, smoking and various foods. If you have only moderately elevated metanephrines, then your healthcare provider may re-evaluate your medications, diet, and stress level to look for interfering substances or conditions. Once these are resolved, you may be tested again to determine whether the metanephrines are still elevated. Sometimes the plasma free metanephrines test will be done along with 24-hour urine metanephrines testing and/or followed by catecholamines testing or imaging procedures to help decide if a catecholamine-secreting tumor is present.

  • Is there anything else I should know?

    While the plasma free metanephrines test can help detect and diagnose the presence of a tumor that produces catecholamines, it cannot tell the healthcare provider the location of the tumor or whether it is benign or malignant (although most are benign). Imaging studies may be used to locate the tumor and genetic testing may be used to determine potential malignancy.

    About 25% of PPGL occur in the setting of a hereditary syndrome associated with alterations in specific genes. These genetic syndromes have thus been identified as carrying an increased tumor risk. Examples include von Hippel-Lindau [VHL] disease and multiple endocrine neoplasia type 2 [MEN2] syndrome. (For more information on these, see Genetics Home Reference: Multiple Endocrine Neoplasia.)

  • Can I have more than one pheochromocytoma at once?

    Yes. Usually a single adrenal tumor will arise in one gland or the other, but multiple tumors can form. This is more likely in people with a strong family history of pheochromocytomas. You may have a tumor in each adrenal gland or occasionally in other locations.

  • Does the amount of plasma free metanephrines detected correspond to the size of the tumor?

    No, it has more to do with the characteristics of the tumor. Even a very small tumor can produce large amounts of catecholamines.

  • Is it really necessary to follow the dietary restrictions?

    The level of catecholamines (and their metabolites) in blood is affected by diet. For test accuracy, interfering substances need to be avoided. Various foods, including caffeine-containing foods such as coffee and energy drinks, and chocolate, as well as cigarette and cigar smoking may interfere with the test and should be avoided prior to testing. It is important to follow the instructions given by your healthcare provider and the specimen collecting site.

  • Is it really necessary to lie down before testing?

    You may be seated for the blood sample collection. However, recent guidelines suggest that it is preferable for the patient to be lying down. The healthcare provider or the collection site will instruct you as to their specific requirements.

See More Common Questions See Less Common Questions
Related Content

On This Site

Tests
Catecholamines
Urine Metanephrines
Vanillylmandelic Acid (VMA)
Conditions
Endocrine System and Syndromes
Hypertension

Elsewhere On The Web

National Organization for Rare Disorders: Pheochromocytoma
NIH, NICHD: Pheochromocytoma
Mayo Clinic: Pheochromocytoma
MedlinePlus: Pheochromocytoma
Genetics Home Reference: Hereditary paraganglioma-pheochromocytoma
National Cancer Institute: Pheochromocytoma and Paraganglioma Treatment (PDQ®)
Hormone Health Network: The Endocrine System
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.

See More
See Less

Ask a Laboratory Scientist

This form enables patients to ask specific questions about lab tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. Please allow 2-3 business days for an email response from one of the volunteers on the Consumer Information Response Team.

Disclaimer
Thank you for using the Consumer Information Response Service (“the Service”) to inquire about the meaning of your lab test result. The Service is provided free of charge by the American Society for Clinical Laboratory Science.

Please note that information provided through this free Service is not intended to be medical advice and should not be relied on as such. Although the laboratory strives to provide the largest single source of objective, scientific data on patient status, it is only one part of a complex biological picture of health or disease. As professional clinical laboratory scientists, our goal is to assist you in understanding the purpose of laboratory tests and the general meaning of your laboratory results. It is important that you communicate with your physician so that together you can integrate the pertinent information, such as age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.) to determine your health status. The information provided through this Service is not intended to substitute for such consultations with your physician nor specific medical advice to your health condition.

By submitting your question to this Service, you agree to release and hold harmless the American Society for Clinical Laboratory Science and its affiliates or their past or present officers, directors, employees, agents and Service volunteers (collectively referred to as “ASCLS”) and Lab Tests, LLC and its affiliates or their past or present members, managers, officers, directors, employees, agents and Service volunteers (collectively referred to as the “LT Parties”) from any legal claims, rights or causes of action you may have relating to or arising out of your use of the Service or in connection with the responses provided to the questions that you submit to the Service.

ASCLS and the LT Parties hereby disclaim any and all liability arising out of your use of this Service or for any adverse outcome from your use of the information provided by this Service for any reason, including but not limited to any misunderstanding or misinterpretation of the information provided through this Service.
See Full Form See Less