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HelpOrder Code PMET Metanephrines, Fractionated, Free, Plasma
Additional Codes
Epic Order ID LAB2405
Reporting Name
Metanephrines, Fract., Free, PUseful For
Screening test for presumptive diagnosis of catecholamine-secreting pheochromocytomas or paragangliomas
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen 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 | Special Container |
|---|---|---|---|
| Plasma EDTA | Frozen (preferred) | 28 days | |
| Refrigerated | 14 days | ||
| Ambient | 7 days |
Reference Values
METANEPHRINE, FREE
<0.50 nmol/L
NORMETANEPHRINE, FREE
<0.90 nmol/L
Day(s) Performed
Monday through Saturday
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
83835
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| PMET | Metanephrines, Fract., Free, P | 57772-6 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 10140 | Normetanephrine, Free | 40851-8 |
| 10139 | Metanephrine, Free | 49700-8 |
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.
Clinical Reference
1. Eisenhofer G. Free or total metanephrines for diagnosis of pheochromocytoma: what is the difference? Clin Chem. 2001;47(6):988-989
2. Lenders JW, Pacek K, Walther MM, et al. Biochemical diagnosis of pheochromocytoma: which test is best? JAMA. 2002;287(11):1427-1434
3. Sawka AM, Jaeschke R, Singh RJ, Young WF Jr. A comparison of biochemical tests for pheochromocytoma: measurement of fractionated plasma metanephrines compared to the combination of 24-hour urinary metanephrines and catecholamines. J Clin Endocrinol Metab. 2003;88(2):553-558
4. Algeciras-Schimnich A, Preissner CM, Young WF Jr, et al. Plasma chromogranin A or urine fractionated metanephrines follow-up testing improves the diagnostic accuracy of plasma fractionated metanephrines for pheochromocytoma. J Clin Endocrinol Metab. 2008;93(1):91-95. doi:10.1210/jc.2007-1354
5. Eisenhofer G, Deutschbein T, Constantinescu G, et al. Plasma metanephrines and prospective prediction of tumor location, size and mutation type in patients with pheochromocytoma and paraganglioma. Clin Chem Lab Med. 2020;59(2):353-363. doi:10.1515/cclm-2020-0904
6. Taylor RL, Singh RJ. Validation of liquid chromatography-tandem mass spectrometry method for analysis of urinary conjugated metanephrine and normetanephrine for screening of pheochromocytoma. Clin Chem 2002;48(3):533-539
Report Available
2 to 5 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
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)