Metanephrine, 24-Hour Urine
Measures metanephrine, a breakdown product of adrenaline, in all the urine you collect over 24 hours. Doctors use it to look into adrenal gland tumors.
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The usual range for Urine metanephrine depends on sex. Choose female or male above to see where you stand.
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What it is
Metanephrine forms when your body breaks down epinephrine (adrenaline), a stress hormone made by the adrenal glands. Some of it leaves in your urine. For this test you collect all of your urine for 24 hours, and the lab measures how much metanephrine it holds. It is usually ordered together with normetanephrine, which comes from norepinephrine, as a "fractionated metanephrines" test.
Why it matters
Doctors mostly use this test when they are looking into rare tumors of the adrenal glands or nearby nerve tissue, called pheochromocytoma and paraganglioma. These tumors can release extra adrenaline-type hormones and cause spells of high blood pressure, headache, sweating and a pounding heartbeat. Metanephrines are made steadily, so they give a steadier signal than adrenaline itself. Because these tumors are rare, most mildly raised results turn out to have another cause.
If it’s low
A result below your lab's range is less often useful for this test than a high one. The most common reason is a collection that missed some urine, which makes the total look smaller than it really was.
Common causes
- A collection that was incomplete or shorter than 24 hours
- Medicines that block the body's production of adrenaline-type hormones, such as metyrosine
What can help
- Check that all the urine was collected and handed in, with the start time, end time and total volume written down
- Ask your clinician whether the collection looks complete
If it’s high
A result above your lab's range means more metanephrine than usual passed into your urine. Most of the time the cause is not a tumor. Medicines, caffeine, smoking, hard exercise, stress, illness and imperfect collections are much more common reasons. ARUP notes that results under about twice the upper limit are usually due to these everyday causes. Results three or more times the upper limit are linked to a higher chance of a tumor and are followed up more closely. Your clinician can put your number in context.
Common causes
- Medicines such as tricyclic antidepressants, SNRI antidepressants, MAO inhibitors, labetalol, sotalol, decongestants and stimulants
- Caffeine and tobacco
- Hard exercise, emotional or physical stress, or a serious illness
- High blood pressure itself, which can raise results slightly
- A collection that did not follow the lab's instructions
- Rarely, a tumor of the adrenal gland or nearby nerve tissue that makes adrenaline-type hormones
What can help
- Bring a list of every medicine, supplement and stimulant you use, including cold remedies, caffeine and tobacco, to your visit
- Ask which of them could affect this test and whether anything should change before a repeat. Don't stop any medicine on your own
- Ask your lab for written collection instructions and follow them, including the right container and any limits on caffeine or exercise
Usual ranges
What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.
The usual range depends on sex and age. Choose women or men to see the one that applies.
- Men, 18+58–276 µg/24 h
Sources: Labcorp, Mayo Clinic Laboratories, ARUP Laboratories
- Women, 18+36–209 µg/24 h
Sources: Labcorp, Mayo Clinic Laboratories, ARUP Laboratories
See Urine metanephrine by age and sex, with the U.S. survey numbers where they exist.
What can affect your result
- Age and sex: labs use different ranges for children, men and women
- Medicines, caffeine, tobacco, hard exercise and stress around the collection
- A full, correctly timed 24-hour collection in the container and preservative your lab provides
- Blood pressure: people with high blood pressure often have slightly higher results
- Kidney function: reduced kidney function changes how much of these substances reaches the urine, so urine results are harder to interpret and doctors sometimes rely on a blood test instead
- The lab: adult upper limits printed by Labcorp, Mayo Clinic Laboratories and ARUP differ
- Tricyclic antidepressants, SNRI antidepressants, MAO inhibitors, labetalol, sotalol, decongestants, stimulants and levodopa can raise results.
- Caffeine, tobacco and strenuous exercise during the collection can raise results.
- A collection that is incomplete, or runs longer than 24 hours, changes the total. Labs differ on preservatives: Mayo prefers boric acid or acetic acid, Labcorp accepts no preservative or hydrochloric acid, and Quest and ARUP reject boric acid (ARUP also rejects acetic acid). Use the container and instructions from the lab that will run your test.
- Mass spectrometry (LC-MS/MS) is not affected by the substances that disturbed older color-based methods, according to Mayo.
Reflects what your body made over the 24 hours collected.
When to talk to a clinician
Talk with your clinician about any result your lab flags, especially one that is about three times the upper limit or higher, or if you also have repeated spells of pounding heartbeat, severe headache and sweating with high blood pressure. If you feel unwell, for example with chest pain, trouble breathing, confusion or fainting, call 911 or your local emergency number.
Questions you could ask
- Why was this test ordered for me?
- Is there anything I should avoid before a repeat collection?
- Could any of my medicines, caffeine, tobacco or recent stress explain this result?
- Was my collection complete and done the way the lab asked?
- How far above the range is my result, and are there next steps?
- Could my collection have been incomplete?
Questions people ask
Why does every lab print a different range?
Labs use different methods and different groups of healthy people to set their ranges. For adult men, the upper limit is 261 µg/24 h at Mayo Clinic Laboratories, 276 at Labcorp and 320 at ARUP. Use the range printed on your own report.
Do I need to stop my medicines before the collection?
Some medicines can raise the result, and labs give different advice about them. Only the clinician who ordered your test can say whether any change is safe for you, so ask before the collection and never stop a medicine on your own.
How do I convert µg/24 h to nmol/24 h?
Multiply µg/24 h by 5.07. For example, 100 µg/24 h is about 507 nmol/24 h. To get µmol/24 h, divide nmol/24 h by 1,000.
Show the science and sources
Units
- 1 µg/24 h = 1 µg/24 h
- 1 µg/24 h = 5.07 nmol/24 h
- 1 µg/24 h = 0.00507 µmol/24 h
Open the Urine metanephrine unit converter
For clinicians and researchers
Metanephrine is the 3-O-methylated metabolite of epinephrine, formed by catechol-O-methyltransferase in chromaffin cells. Chromaffin tumors make metanephrines continuously, independent of catecholamine release, so metanephrines outperform the parent catecholamines in sensitivity. The Endocrine Society (2014) recommends plasma free or urinary fractionated metanephrines as the initial biochemical test for pheochromocytoma and paraganglioma, with attention to preanalytical causes of false positives. Labs run LC-MS/MS on preserved 24-hour urine; Mayo acid-hydrolyzes and heats the urine before extraction, so its result reflects deconjugated metanephrine. LC-MS/MS avoids the interferences of the older Pisano colorimetric method. Intervals vary by lab, age and sex (Labcorp adults: 58–276 µg/24 h in men, 36–209 in women). Mayo and ARUP also publish a cut-off for people with hypertension (metanephrine under 400 µg/24 h) because essential hypertension commonly gives slight increases. Because these tumors are very rare (Mayo cites a prevalence under 1 in 100,000), false positives outnumber true positives (Labcorp); values three or more times the upper limit are rarely false positive (Labcorp, ARUP). Isolated normetanephrine increases from drugs and sympathetic activation are more common than isolated metanephrine increases. Per-day results assume a complete 24-hour collection; creatinine-normalized results (µg/g creatinine) are not interchangeable with per-day results.
LOINC 19049-6 (primary), 104629-1, 11140-1. Specimen: urine-24h.
Sources
- Metanephrines, Fractionated, Quantitative, 24-Hour Urine (test 004234), Labcorp
- Metanephrines, Fractionated, 24 Hour, Urine (test METAF), Mayo Clinic Laboratories
- Metanephrines Fractionated by HPLC-MS/MS, Urine (test 2007996), ARUP Laboratories
- Metanephrines, Fractionated, LC/MS/MS, 24-Hour Urine (test 14962), Quest Diagnostics
- Pheochromocytoma and Paraganglioma: An Endocrine Society Clinical Practice Guideline, Journal of Clinical Endocrinology & Metabolism (2014)
- Pitfalls in the Diagnostic Evaluation of Pheochromocytomas, Journal of the Endocrine Society (2024)
- Metanephrine (PubChem CID 21100), National Library of Medicine
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