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HelpTest ID METAR Metanephrines, Fractionated, Random, Urine
Reporting Name
Metanephrines, Fract., Random, UUseful For
A second-order screening test for the presumptive diagnosis of pheochromocytoma in patients with nonepisodic hypertension
Confirming positive plasma metanephrine results in patients with nonepisodic hypertension
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| RCTU | Creatinine Conc | No | Yes |
| METAU | Metanephrines, Fractionated, U | No | Yes |
Specimen Type
UrineSpecimen Required
Supplies: Urine Tubes, 10 mL (T068)
Patient Preparation: Tricyclic antidepressants and labetalol and sotalol (beta blockers) may elevate levels of metanephrines. If clinically feasible, these medications should be discontinued at least 1 week before collection.
Collection Container/Tube: Clean, plastic urine collection container
Submission Container/Tube: Plastic urine tube
Specimen Volume: 5 mL
Collection Instructions:
1. Collect a random urine specimen.
2. No preservative.
Specimen Minimum Volume
3 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 28 days | |
| Ambient | 28 days | ||
| Frozen | 28 days |
Reference Values
METANEPHRINE/CREATININE
Normotensives
0-2 years: 82-418 mcg/g creatinine
3-8 years: 65-332 mcg/g creatinine
9-12 years: 41-209 mcg/g creatinine
13-17 years: 30-154 mcg/g creatinine
≥18 years: 29-158 mcg/g creatinine
NORMETANEPHRINE/CREATININE
Males
Normotensives
0-2 years: 121-946 mcg/g creatinine
3-8 years: 92-718 mcg/g creatinine
9-12 years: 53-413 mcg/g creatinine
13-17 years: 37-286 mcg/g creatinine
18-29 years: 53-190 mcg/g creatinine
30-39 years: 60-216 mcg/g creatinine
40-49 years: 69-247 mcg/g creatinine
50-59 years: 78-282 mcg/g creatinine
60-69 years: 89-322 mcg/g creatinine
≥70 years: 102-367 mcg/g creatinine
Females
Normotensives
0-2 years: 121-946 mcg/g creatinine
3-8 years: 92-718 mcg/g creatinine
9-12 years: 53-413 mcg/g creatinine
13-17 years: 37-286 mcg/g creatinine
18-29 years: 81-330 mcg/g creatinine
30-39 years: 93-379 mcg/g creatinine
40-49 years: 107-436 mcg/g creatinine
50-59 years: 122-500 mcg/g creatinine
60-69 years: 141-574 mcg/g creatinine
≥70 years: 161-659 mcg/g creatinine
TOTAL METANEPHRINE/CREATININE
Males
Normotensives
0-2 years: 241-1,272 mcg/g creatinine
3-8 years: 186-980 mcg/g creatinine
9-12 years: 110-582 mcg/g creatinine
13-17 years: 78-412 mcg/g creatinine
18-29 years: 96-286 mcg/g creatinine
30-39 years: 106-316 mcg/g creatinine
40-49 years: 117-349 mcg/g creatinine
50-59 years: 130-386 mcg/g creatinine
60-69 years: 143-427 mcg/g creatinine
≥70 years: 159-472 mcg/g creatinine
Females
Normotensives
0-2 years: 241-1,272 mcg/g creatinine
3-8 years: 186-980 mcg/g creatinine
9-12 years: 110-582 mcg/g creatinine
13-17 years: 78-412 mcg/g creatinine
18-29 years: 131-467 mcg/g creatinine
30-39 years: 147-523 mcg/g creatinine
40-49 years: 164-585 mcg/g creatinine
50-59 years: 184-655 mcg/g creatinine
60-69 years: 206-733 mcg/g creatinine
≥70 years: 230-821 mcg/g creatinine
Day(s) and Time(s) Performed
Monday through Friday; 4 p.m.
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
83835
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| METAR | Metanephrines, Fract., Random, U | 68317-7 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 21546 | Metanephrine/Creatinine | 9645-3 |
| RCTU | Creatinine Conc | 2161-8 |
| 21547 | Normetanephrine/Creatinine | 13783-6 |
| 21548 | Total Metanephrine/Creatinine | 13771-1 |
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").
Pheochromocytomas and other tumors derived from neural crest cells (eg, paragangliomas and neuroblastomas) secrete catecholamines (epinephrine and norepinephrine).
Metanephrine and normetanephrine are the 3-methoxy metabolites of epinephrine and norepinephrine, respectively. Metanephrine and normetanephrine are both further metabolized to vanillylmandelic acid.
Pheochromocytoma cells also have the ability to oxymethylate catecholamines into metanephrines that are secreted into circulation.
While screening for pheochromocytoma is best accomplished by measuring plasma free fractionated metanephrines (a more sensitive assay), follow-up testing with urinary fractionated metanephrines (a more specific assay) may identify false-positives. Twenty-four hour urine collections are preferred, especially for patients with episodic hypertension; ideally the collection should begin at the onset of a "spell."
Interpretation
Increased metanephrine and normetanephrine levels are found in patients with pheochromocytoma and tumors derived from neural crest cells.
Increased urine metanephrines can be detected in nonpheochromocytoma hypertensive patients; quantification may help distinguish these patients from those with tumor-induced symptoms.
Clinical Reference
1. van Duinen N, Corssmit EPM, de Jong WHA, et al: Plasma levels of free metanephrines and 3-methoxytyramine indicate a higher number of biochemically active HNPGL than 24-h urinary excretion rates of catecholamines and metabolites European J Endocrinol 2013;169:377-382 doi: 10.1530/EJE-13-0529
2. Pacak K, Linehan WM, Eisenhofer G, et al: Recent advances in genetics, diagnosis, localization, and treatment of pheochromocytoma. Ann Intern Med 2001;134:315-329
3. Sawka AM, Singh RJ, Young WF Jr: False positive biochemical testing for pheochromocytoma caused by surreptitious catecholamine addition to urine. Endocrinologist 2001;11:421-423
4. Eisenhofer G, Grebe S, Cheung NKV: Chapter 63: Monoamine-producing tumors. In Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Sixth edition. Edited by N Rafai, AR Horvath, CT Wittwer. Elsevier, 2018 pp 1421
5. Shen Y, Cheng L: Chapter 2: Biochemical diagnosis of pheochromocytoma and paraganglioma. In Paraganglioma: A Multidisciplinary Approach. Edited by R. Mariani-Costantini. Codon Publications; 2019 doi:10.15586/paraganglioma.2019.ch2. Accessed: April 2020. Available at www.ncbi.nlm.nih.gov/books/NBK543224/
Analytic Time
3 days (not reported on Sundays)Method Name
RCTU: Enzymatic Colorimetric Assay
METAU: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Stable Isotope Dilution Analysis
Forms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.