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HelpTEST ID PMET Metanephrines, Fractionated, Free, Plasma
Reporting Name
Metanephrines, Fract., Free, PSpecimen Type
Plasma EDTASpecimen Required
Patient Preparation: Use of an Epi-pen within the last 7 days may produce inaccurate results.
Supplies: Sarstedt Aliquot Tube, 5 mL (T914)
Collection Container/Tube: Lavender top (EDTA)
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Within 2 hours of collection centrifuge and aliquot plasma into a plastic vial.
Specimen Minimum Volume
0.3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Plasma EDTA | Frozen (preferred) | 28 days |
| Refrigerated | 14 days | |
| Ambient | 7 days |
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Reject Due To
| Gross hemolysis | OK |
| Gross lipemia | OK |
| Gross icterus | OK |
Reference Values
METANEPHRINE, FREE
<0.50 nmol/L
NORMETANEPHRINE, FREE
<0.90 nmol/L
Day(s) Performed
Monday through Saturday
Report Available
2 to 5 daysSpecimen Retention Time
2 weeksPerforming Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
83835
Forms
If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:
-General Request (T239)
-Oncology Test Request (T729)
-Renal Diagnostics Test Request (T830)
Useful For
Screening test for presumptive diagnosis of catecholamine-secreting pheochromocytomas or paragangliomas
Clinical Information
Pheochromocytoma is a rare, though potentially lethal, tumor of chromaffin cells of the adrenal medulla that produces episodes of hypertension with palpitations, severe headaches, and sweating ("spells"). Patients with pheochromocytoma may also be asymptomatic and present with sustained hypertension or an incidentally discovered adrenal mass.
Pheochromocytomas and other tumors derived from neural crest cells (eg, paragangliomas and neuroblastomas) secrete catecholamines (epinephrine, norepinephrine, and dopamine). Metanephrine and normetanephrine (collectively referred to as metanephrines) are the 3-methoxy metabolites of epinephrine and norepinephrine, respectively. The metanephrines are stable metabolites and are cosecreted directly with catecholamines by pheochromocytomas and other neural crest tumors. This results in sustained elevations in plasma free metanephrine levels, making them more sensitive and specific than plasma catecholamines in the identification of pheochromocytoma patients.(1) Metanephrine and normetanephrine are both further metabolized to conjugated metanephrines and vanillylmandelic acid.