Metanephrines, Free
Label Mnemonic: METP
Epic Lab Code: LAB3587
Downtime Form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Commercial Mail-out Laboratory
5231 RCP
Specimen Instructions:
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.
Collection Medium:
Pink top tube 6 mL (K2-EDTA)
Preferred Minimum: 2 mL plasma from lavender top (EDTA) tube
Absolute Minimum: 1 mL plasma from lavender top (EDTA) tube
Rejection Criteria:
Plasma separator tubes. Body fluids other than EDTA or heparinized plasma. Non-frozen specimens.
Delivery Instructions:
Deliver to laboratory immediately after collection.
Turn Around Time:
2-4 days upon receipt in reference laboratory
Reference Range:
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.
Note: 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.
Quantitative Liquid Chromatography-Tandem Mass Spectrometry
CPT Code:
See Additional Information:
Specimens Requiring Immediate Delivery