Normetanephrine, 24-Hour Urine
Measures normetanephrine, a breakdown product of norepinephrine, in all the urine you collect over 24 hours. Doctors use it to look into adrenal gland tumors.
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What it is
Normetanephrine forms when your body breaks down norepinephrine, a stress hormone and nerve messenger. 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 normetanephrine it holds. It is usually ordered together with metanephrine, which comes from epinephrine (adrenaline), as a "fractionated metanephrines" test. Typical levels rise a little with age.
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 norepinephrine and cause spells of high blood pressure, headache, sweating and a pounding heartbeat. Normetanephrine is one of the two numbers this test reports. It is also the one that everyday causes raise most often, so mildly raised results usually have another explanation.
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 normetanephrine 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, and isolated rises of up to two to three times the upper limit are often seen. 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 (venlafaxine, duloxetine), MAO inhibitors, some antipsychotics, labetalol, sotalol, decongestants and stimulants
- Caffeine and tobacco
- Hard exercise, emotional or physical stress, or a serious illness
- Obstructive sleep apnea
- 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, 21–30110–553 µg/24 h
Sources: Labcorp, Mayo Clinic Laboratories, ARUP Laboratories
- Men, 31+156–729 µg/24 h
Sources: Labcorp, Mayo Clinic Laboratories, ARUP Laboratories
- Women, 21–3095–449 µg/24 h
Sources: Labcorp, Mayo Clinic Laboratories, ARUP Laboratories
- Women, 31+131–612 µg/24 h
Sources: Labcorp, Mayo Clinic Laboratories, ARUP Laboratories
See Urine normetanephrine by age and sex, with the U.S. survey numbers where they exist.
What can affect your result
- Age and sex: ranges are lower in children and rise with age, and they differ between 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 (such as venlafaxine and duloxetine), MAO inhibitors, labetalol, sotalol, some antipsychotics, 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, sleep problems 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 is my normetanephrine result raised when my metanephrine is normal?
Most normetanephrine comes from norepinephrine released by nerves, so everyday things raise it more easily than metanephrine. These include certain antidepressants and other medicines, caffeine, stress and sleep apnea. A single raised normetanephrine, especially under two to three times the upper limit, often has one of these explanations. Ask your clinician what it means for you.
Why do ranges differ by age and lab?
Normetanephrine rises with age, so labs set separate ranges for children and for older adults. Labs also use different methods and groups of healthy people. For men over 30, the upper limit is 729 µg/24 h at Labcorp and 865 at ARUP. Use the range printed on your own report.
How do I convert µg/24 h to nmol/24 h?
Multiply µg/24 h by 5.46. For example, 100 µg/24 h is about 546 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 = 5.459 nmol/24 h
- 1 µg/24 h = 0.005459 µmol/24 h
Open the Urine normetanephrine unit converter
For clinicians and researchers
Normetanephrine is the 3-O-methylated metabolite of norepinephrine, formed by catechol-O-methyltransferase. About 75% of it comes from norepinephrine released by sympathetic nerves rather than from the adrenal medulla, which is why drugs that block norepinephrine reuptake (tricyclics, SNRIs, phenoxybenzamine), sleep apnea and sympathetic activation raise it so often (Fagundes 2024). Isolated increases up to two to three times the upper limit are the most common false-positive pattern. The Endocrine Society (2014) recommends plasma free or urinary fractionated metanephrines as the initial biochemical test for pheochromocytoma and paraganglioma. Labs use LC-MS/MS; Mayo acid-hydrolyzes and heats the urine before extraction, so its result reflects deconjugated normetanephrine. Upper limits rise with age at every lab (Labcorp men: 405 µg/24 h at ages 13–20, 729 above 30). Mayo and ARUP give a hypertension cut-off (normetanephrine under 900 µg/24 h). Values three or more times the upper limit are rarely false positive (Labcorp, ARUP). Per-day results assume a complete 24-hour collection; ARUP suggests creatinine ratios (µg/g creatinine) when the collection time or volume is off, and those ratios are not interchangeable with per-day results.
LOINC 2671-6 (primary), 104631-7, 15083-9. 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)
- Normetanephrine (PubChem CID 1237), National Library of Medicine
AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.