Metanephrines, Fract, Free, Fractionated metanephrines, Metanephrines free, plasma, Normetanephrines, free, plasma, Plasma Free Metanephrines, Metanephrines, Free, Plasma, Metanephrines, Fractionated, Free, Plasma, MAYO: PMET, Antrim #83127, EPIC: LAB6099, SOFT: XMETN
Specimen Collection Criteria
Collect: One Lavender-top EDTA tube.
Send specimen to the Laboratory immediately after collection for processing.
Physician Office/Drawsite Specimen Preparation
Centrifuge to separate plasma from cells within 30 minutes of collection. Transfer plasma to plastic transport tube and freeze (-20°C/-4°F or below) immediately.
Preparation for Courier Transport
Transport: 1.0 mL plasma, frozen (-20°C/-4°F or below). (Min: 0.3 mL)
- Hemolyzed specimens.
- Specimens not collected and processed as indicated.
Specimen Stability for Testing:
Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 14 days
Specimen Storage in Department Prior to Disposal:
Specimen retention time is determined by the policy of the reference laboratory. Contact the Sendout Laboratory with any questions.
Sent to Mayo Medical Laboratories, Rochester, MN.
Monday - Saturday.
Results available in 3-5 days.
Metanephrine, Free: Less than 0.50 nmol/L.
Normetanephrine, Free: Less than 0.90 nmol/L.
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS).
Pheochromocytoma is a rare tumor of neural crest cell origin that can present with episodic or sustained hypertension, palpitations, severe headaches, sweating, or they can be asymptomatic. Phenochromocytomas and other tumors derived from neural crest cells (i.e.-paragangliomas and neuroblastomas) secrete catecholamines (epinephrine, norepinephrine and dopamine) and/or their metabolites (metanephrine, normetanephrine-collectively called metanephrines). The metanephrines are stable metabolites and are co-secreted directly with catecholamines. This results in sustained levels, making them more sensitive and specific than plasma catecholamines in the identification of pheochromocytomas. The metanephrines can be further metabolized to vanillylmandelic acid (VMA).
Substances that increase endogenous catecholamine levels can result in borderline elevations of plasma metanephrines. These include 1) monoamine oxidase inhibitors particularly when combined with tyrosine-rich foods such as nuts, bananas, cheese, 2) catecholamine reuptake inhibitors such as cocaine or cocaine derivatives, includes some local anesthetics and antiarrhythmic drugs 3) some anesthetic gases such as halothane 4) withdrawal from sedative drugs, includes alcohol, benzodiazepines, opioids, and some central acting anthypertensive medications such as clonidine.
Artifactually low levels of plasma metanephrines may be observed in patients receiving metyrosine.
This assay is most useful in screening for tumors derived from neural crest cells such as pheochromocytomas and paragangliomas.
MAYO: PMET, Antrim #83127, EPIC: LAB6099, SOFT: XMETN