Metanephrines, Plasma (Free)
Ordering Recommendation

First-line test in suspected pheochromocytoma.

Quantitative Liquid Chromatography-Tandem Mass Spectrometry
2-4 days
New York DOH Approval Status
This test is New York DOH approved.
Submit With Order
ARUP Consult®
Disease Topics
Specimen Required
Patient Preparation
Drugs and medications may affect results and should be discontinued for at least 72 hours prior to specimen collection, if possible. Collection of the specimen after the patient has rested for 15 minutes in a supine position is recommended. 
Lavender (EDTA), pink (K2EDTA), or green (sodium or lithium heparin). 
Specimen Preparation
Centrifuge within 1 hour. Transfer 2 mL plasma to an ARUP Standard Transport Tube and freeze immediately. (Min: 1 mL) Avoid hemolysis. 
Storage/Transport Temperature
Frozen. Separate specimens must be submitted when multiple tests are ordered. 
Unacceptable Conditions
Plasma separator tubes. Body fluids other than EDTA or heparinized plasma. Non-frozen specimens. 
After separation from cells: Ambient: Unacceptable; Refrigerated: Unacceptable; Frozen: 1 month 
Reference Interval
Normetanephrine: 0.0-0.89 nmol/L
Metanephrine: 0.0-0.49 nmol/L
Interpretive Data
This test is useful in the detection of pheochromocytoma, a rare neuroendocrine tumor. The majority of patients with pheochromocytoma have a plasma normetanephrine concentration in excess of 2.2 nmol/L and/or a metanephrine concentration in excess of 1.1 nmol/L. Increased concentrations of these analytes serve as confirmation for diagnosis. Patients with essential hypertension and plasma concentrations of normetanephrine below 0.9 nmol/L and a metanephrine concentration below 0.5 nmol/L, can be excluded from further testing. If clinical suspicion remains, repeat testing or testing for metanephrines in a 24-hr. urine specimen should be considered.

Compliance Statement B: For laboratory developed tests not using a RUO kit, and for FDA approved, cleared or 510(k) exempt assays with alterations. This test was developed and its performance characteristics determined by ARUP Laboratories. The U. S. Food and Drug Administration has not approved or cleared this test; however, FDA clearance or approval is not currently required for clinical use. The results are not intended to be used as the sole means for clinical diagnosis or patient management decisions.

Isoetharine, isoproterenol, 3,4-methylenedioxyamphetamine (MDA), and 3,4-methylenedioxymethamphetamine (MDMA) are known to interfere in this test.

Many drugs/medications, including over-the-counter and herbal products, can interfere with test results. Testing for all potential interactions is not possible.  If the patient is taking a drug not listed as an interferent, its potential effect on test results is unknown. If test results are inconsistent with clinical evidence, drug interference should be considered. If appropriate, the patient should discontinue the potential interferent for 48-72 hours and a new sample collected for retesting.
Hotline History
Component Test Code*Component Chart NameLOINC
0050192Metanephrines Interpretation48767-8
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.
  • Fractionated metanephrines
  • Fractionated Plasma Free Metanephrines
  • Free Metanephrine
  • Metanephrine
  • Metanephrines, Fractionated
  • NMN, plasma
  • Normetanephrine
  • Normetanephrine, free
  • Plasma Metanephrines
  • Quantitative Metanephrines