Adrenaline levels are tested indirectly, by measuring breakdown products called metanephrines in your blood or urine. Direct measurement of adrenaline itself is possible but less reliable because adrenaline surges and crashes within seconds, making a single blood draw easy to mistime. Metanephrines, the compounds your body produces as it processes adrenaline, linger much longer in the bloodstream and give a far more stable reading.
Why Doctors Don’t Measure Adrenaline Directly
Adrenaline (also called epinephrine) has a very short half-life. It spikes in response to stress, pain, cold, or even the anxiety of having blood drawn. A direct plasma epinephrine test exists, with a normal range of 0 to 140 pg/mL, but the reading can swing dramatically based on your emotional state at the moment the needle goes in. That makes the number hard to interpret.
Instead, most doctors order a test for “plasma free metanephrines” or “24-hour urine fractionated metanephrines.” These breakdown products accumulate steadily, so they reflect your overall adrenaline output rather than a single moment. Plasma free metanephrines have a sensitivity approaching 96% to 100% for detecting adrenaline-producing tumors, which is why this test has become the standard.
The Blood Test: Plasma Free Metanephrines
This is the most common first-line test. A technician draws blood from your arm into a standard tube, and the sample is analyzed using a method called mass spectrometry. The key detail that separates this from a routine blood draw is the preparation: you need to lie flat on your back in a quiet room for 30 minutes before the blood is taken. Sitting upright or standing activates your sympathetic nervous system and raises catecholamine levels enough to produce a misleading result.
You’ll typically be asked to fast for about 10 hours before the test, though water is usually fine. Stressful situations and vigorous exercise should be avoided beforehand for the same reason: anything that triggers a fight-or-flight response will push your numbers up artificially.
The Urine Test: 24-Hour Collection
A 24-hour urine collection captures your total adrenaline output over a full day, smoothing out any short-term spikes. The process works like this: you discard your first morning void, then collect every subsequent sample in a provided container for the next 24 hours, including the first void the following morning. The container needs to stay refrigerated the entire time, and it usually contains a preservative solution to keep the sample stable.
The lab measures fractionated metanephrines (the individual components rather than a single total), along with catecholamines and sometimes a compound called vanillylmandelic acid. Normal 24-hour values generally fall below 400 mcg for total metanephrines in women under 30, with ranges increasing slightly with age. Men have somewhat higher normal ranges. Each lab publishes its own reference values, so your report will include the specific cutoffs used.
One advantage of the urine test is that it doesn’t require you to lie flat in a clinic. One disadvantage is that collecting every void for 24 hours is inconvenient, and a missed sample throws off the results.
Foods and Medications That Skew Results
Several common substances can push metanephrine or catecholamine levels high enough to trigger a false positive. You’ll generally be asked to stop certain medications at least 72 hours before testing, if your doctor considers it safe to do so. The biggest offenders include beta-blockers, decongestants containing pseudoephedrine or similar stimulants, and cocaine. Each of these raises both adrenaline and its breakdown products in measurable ways.
Diet restrictions typically begin 24 hours before the test and continue throughout the collection period if you’re doing a urine test. The foods to avoid include coffee, tea, chocolate, cocoa, bananas, and anything flavored with vanilla. These contain compounds that can interfere with the lab assay or directly affect catecholamine metabolism. Nicotine also raises catecholamine levels, so you should avoid tobacco products before testing.
What the Results Mean
The most common reason doctors order these tests is to rule out a pheochromocytoma, a rare tumor of the adrenal gland that produces excess adrenaline. If your plasma metanephrine and normetanephrine levels come back normal, a pheochromocytoma is extremely unlikely. The test’s near-perfect sensitivity means a normal result is highly reassuring.
Mildly elevated results are trickier. Stress, improper positioning during the blood draw, or one of the medications listed above can all produce a modest bump. When results fall in a gray zone, your doctor may repeat the test under more controlled conditions or move to a confirmation step called a clonidine suppression test.
The Clonidine Suppression Test
This follow-up test helps distinguish a true tumor from a false positive. Clonidine is a blood pressure medication that tells your nervous system to dial back its release of norepinephrine (adrenaline’s close cousin). In a healthy person, taking clonidine will cause metanephrine levels to drop significantly. In someone with a pheochromocytoma, the tumor keeps producing catecholamines regardless because it doesn’t respond to the same signals your nervous system does. If plasma normetanephrine levels fail to drop by more than 40% from baseline after three hours, or if they actually rise, a tumor is the likely explanation.
Which Test Should You Ask For
If you’re experiencing episodes of rapid heartbeat, high blood pressure, sweating, or headaches that come in waves, a plasma free metanephrines test is the standard starting point. It has the highest sensitivity (96% to 100%) and good specificity (85% to 100%), and it only requires a single blood draw. The 24-hour urine collection offers comparable accuracy, with about 97% sensitivity and 98% specificity in recent studies, but the logistics are less convenient.
Some doctors order both tests together to cross-reference results. If you’re being tested because of a known genetic condition that raises your risk of adrenaline-producing tumors, such as multiple endocrine neoplasia or neurofibromatosis, periodic screening with plasma metanephrines is typical even when you have no symptoms.
Keep in mind that no commercial at-home test reliably measures adrenaline or its metabolites. Salivary cortisol kits exist, but cortisol is a different hormone from a different gland with a different function. Testing adrenaline requires either a properly handled blood sample or a preserved 24-hour urine collection, both processed by a certified lab.