Test Id : PMET
Metanephrines, Fractionated, Free, Plasma
Useful For
Suggests clinical disorders or settings where the test may be helpful
Screening test for presumptive diagnosis of catecholamine-
Method Name
A short description of the method used to perform the test
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
Fractionated metanephrines +
Free Metanephrine
Metanephrines free, plasma
NMN (Normetanephrines), plasma
Normetanephrine, (NMN), free
Normetanephrines, plasma
Specimen Type
Describes the specimen type validated for testing
Plasma EDTA
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
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.
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)
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
0.3 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Plasma EDTA | Frozen (preferred) | 28 days | |
| Ambient | 7 days | ||
| Refrigerated | 14 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Screening test for presumptive diagnosis of catecholamine-
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Pheochromocytoma is a rare, though potentially lethal, tumor of
Pheochromocytomas and other tumors derived from neural crest
Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
METANEPHRINE, FREE
<0.50 nmol/L
NORMETANEPHRINE, FREE
<0.90 nmol/L
Interpretation
Provides information to assist in interpretation of the test results
In the normal population, plasma metanephrine and normetanephrine
Measurement of plasma free metanephrines appears to be the best
Due to the low prevalence of pheochromocytomas and related tumors
Elevated results are reported with appropriate comments.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
While most circulating metanephrines are derived directly from adrenal secretion, peripheral conversion of catecholamines makes a small contribution. Therefore, substances that increase endogenous catecholamine levels can result in borderline elevations of plasma metanephrines. These include:
-Monoamine oxidase inhibitors (MAOI-a class of antidepressants with marked effects on catecholamine levels, particularly if the patient consumes tyrosine-rich foods such as nuts, bananas, or cheese)
-Catecholamine reuptake inhibitors including cocaine and synthetic cocaine derivatives such as many local anesthetics, some of which also are antiarrhythmic drugs (eg, lidocaine)
-Some anesthetic gases, particularly halothane
-Withdrawal from sedative drugs, medical or recreational, particularly alcohol, benzodiazepines (eg, Valium), opioids, and some central acting antihypertensive drugs, particularly clonidine, but generally not cannabis or other hallucinogens such as lysergic acid diethylamide, mescal, or peyote
The observed elevations of plasma metanephrines are usually minor.
We are currently not aware of any substances that interfere directly with the assay.
Artifactually decreased plasma metanephrine levels may be observed when patients are already receiving metyrosine treatment. This drug may be administered in suspected or confirmed cases of pheochromocytoma while awaiting definitive treatment. It inhibits tyrosine hydroxylase, the enzyme that catalyzes the first step in catecholamine synthesis.
Supportive Data
This liquid chromatography tandem mass spectrometry (LC-MS/MS) method replaces the in-house high-performance liquid chromatography with electrochemical detection (HPLC-EC) method. The HPLC-EC method was labor intensive, with a complicated extraction and lengthy run time, and was prone to interferences. The LC-MS/MS method correlates well with Mayo Clinic Laboratories previously performed HPLC-EC method: N=92, slope=0.87, intercept=0.05, r(2)=0.95. The reference ranges remain the same as the HPLC-EC method and were validated by method comparison between these methods. LC-MS/MS also correlates with the National Institutes of Health's HPLC-EC method.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
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
Method Description
Describes how the test is performed and provides a method-specific reference
Free metanephrine (MN) and normetanephrine (NMN) are extracted from plasma using solid phase extraction. The concentrated eluate is analyzed using liquid chromatography tandem mass spectrometry and quantified using stable isotope labeled internal standards, d3-MN and d3-NMN . Analytes and internal standards are ionized using electro spray ionization and are detected in the multiple reaction-monitoring mode. The specific transitions for MN, NMN, d3-MN, and d3-NMN are m/z 180.2 to m/z 148.2, 166.2 to m/z 134.2, 183.2 to m/z 151.2, and m/z 169.2 to m/z 137.2, respectively.(Unpublished Mayo method)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Monday through Saturday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
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
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
83835
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| PMET | Metanephrines, Fract., Free, P | 57772-6 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 10140 | Normetanephrine, Free | 40851-8 |
| 10139 | Metanephrine, Free | 49700-8 |