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25535 Metanephrines, Fractionated, Free, Plasma (FMETP)

Metanephrines, Fractionated, Free, Plasma (FMETP)
Test Code: MISC
Synonyms/Keywords
Free Metanephrine, Free Normetanephrine
Test Components
​Metanephrine (MN) - free, Normetanephrine (NMN) - free, Total (MN + NMN) free
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​No ​Plasma ​EDTA Lavender Top Tube (LTT) ​ ​2.5 mL ​1.5 mL ​
Specimen Stability Information
Specimen Type Temperature Time
​Plasma ​ ​Refrigerate (preferred) ​14 days
​Frozen ​14 days
Rejection Criteria
Warm/Room Temperature Sample Heparinized Plasma
​Serum ​CSF
​Urine ​
Interference
False-positive results have been observed in patients with either chronic kidney disease or hypertension. Patient should avoid alcohol, coffee, tea, tobacco and strenuous exercise prior to collection. Overnight fasting is preferred. Patients should be relaxed in either a supine or upright position before blood is drawn.
Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo forwards to Quest Diagnostics Nichols Institute ​Tuesday through Saturday ​3-4 days ​Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
Reference Lab
Mayo Clinic Laboratories
Reference Range Information

Metanephrine, Free: < or = 57 pg/mL
Normetanephrine, Free: < or = 148 pg/mL
Total, Free (MN + NMN): < or = 205 pg/mL

Elevations >4-fold upper reference range: strongly suggestive of pheochromocytoma

Elevations >1 - 4-fold upper reference range: significant but not diagnostic, may be due to medications or stress. Suggest running 24hr urine fractionated metanephrines and serum Chromogranin A for confirmation.

Interpretation
Normetanephrine (NM) and metanephrine (MN) are the extra-neuronal catechol-o-methyl transferase (COMT) metabolites of the catecholamines norepinephrine and epinephrine, respectively. Measurement of plasma metanephrines is more sensitive (but may be less specific) than measurement of catecholamines for the detection of pheochromocytoma. Proper interpretation of results requires awareness of recent medication/drug history (e.g., antyhypertensive agents, alcohol, cocaine) and other pre-analytical factors (e.g., stress, severe congestive heart failure, myocardial infarction) that influence release of catecholamines and metanephrines.
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​83835 ​ ​ ​ ​
Synonyms/Keywords
Free Metanephrine, Free Normetanephrine
Test Components
​Metanephrine (MN) - free, Normetanephrine (NMN) - free, Total (MN + NMN) free
Ordering Applications
Ordering Application Description
If the ordering application you are looking for is not listed, contact your local laboratory for assistance.
Specimen Requirements
Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
​No ​Plasma ​EDTA Lavender Top Tube (LTT) ​ ​2.5 mL ​1.5 mL ​
Specimen Stability Information
Specimen Type Temperature Time
​Plasma ​ ​Refrigerate (preferred) ​14 days
​Frozen ​14 days
Rejection Criteria
Warm/Room Temperature Sample Heparinized Plasma
​Serum ​CSF
​Urine ​
Interference
False-positive results have been observed in patients with either chronic kidney disease or hypertension. Patient should avoid alcohol, coffee, tea, tobacco and strenuous exercise prior to collection. Overnight fasting is preferred. Patients should be relaxed in either a supine or upright position before blood is drawn.
Test Components
​Metanephrine (MN) - free, Normetanephrine (NMN) - free, Total (MN + NMN) free
Reference Range Information

Metanephrine, Free: < or = 57 pg/mL
Normetanephrine, Free: < or = 148 pg/mL
Total, Free (MN + NMN): < or = 205 pg/mL

Elevations >4-fold upper reference range: strongly suggestive of pheochromocytoma

Elevations >1 - 4-fold upper reference range: significant but not diagnostic, may be due to medications or stress. Suggest running 24hr urine fractionated metanephrines and serum Chromogranin A for confirmation.

Interpretation
Normetanephrine (NM) and metanephrine (MN) are the extra-neuronal catechol-o-methyl transferase (COMT) metabolites of the catecholamines norepinephrine and epinephrine, respectively. Measurement of plasma metanephrines is more sensitive (but may be less specific) than measurement of catecholamines for the detection of pheochromocytoma. Proper interpretation of results requires awareness of recent medication/drug history (e.g., antyhypertensive agents, alcohol, cocaine) and other pre-analytical factors (e.g., stress, severe congestive heart failure, myocardial infarction) that influence release of catecholamines and metanephrines.
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Performing Laboratory Information
Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
​Mayo forwards to Quest Diagnostics Nichols Institute ​Tuesday through Saturday ​3-4 days ​Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)
Reference Lab
Mayo Clinic Laboratories
For billing questions, see Contacts
Outreach CPTs
CPT Modifier
(if needed)		 Quantity Description Comments
​83835 ​ ​ ​ ​
For most current information refer to the Marshfield Laboratory online reference manual.