Metanephrines Test

Metanephrines test is ordered when a healthcare provider either suspects that someone has a catecholamine-secreting tumor or wants to rule out the possibility. It may be ordered when a person (especially a person younger than age 40) has sudden bursts of signs and symptoms such as:
High blood pressure
Severe headaches
Sweating
Flushing
Rapid heart rate
Tremor
You also may have fever, chest pain, stomach pain, nausea, vomiting, anxiety, tremors, heat intolerance, and weight loss.
If a person has only moderately elevated metanephrines, then the healthcare provider may re-evaluate the person's medications, diet, and stress level to look for interfering substances or conditions. Once these are resolved, the person may be tested again to determine whether the metanephrines are still elevated and take appropriate action. Sometimes the 24-hour urine metanephrines test will be done in conjunction with plasma free metanephrines testing and/or followed by catecholamines testing to help decide if a catecholamine-secreting tumor is present.

Don't exercise vigorously or drink caffeinated beverages or alcohol before your test. Don't take acetaminophen for at least 48 hours before the test. Try to avoid stress.

You may be asked to rest quietly for 15 to 30 minutes before your blood sample is collected. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.

Urine metanephrines testing is used to help detect or rule out the presence of a rare tumor called a pheochromocytomas or a paraganglioma that releases excess metanephrines. Testing may also be used when a tumor has been treated or removed to monitor for recurrence. The test for metanephrines is very sensitive and false positives do occur. The test is affected by stress, drugs, smoking and various foods such as caffeine-containing drinks and alcohol.

Metanephrines test measures the substances metanephrine and normetanephrine in your blood. It helps find out whether you have a tumor of the adrenal glands called pheochromocytoma. This test needs a 24-hour urine sample. For this sample, you must collect all of your urine for 24 hours. Empty your bladder completely first thing in the morning without collecting it. Note the time, and then collect your urine every time you go to the bathroom over the next 24 hours. Your healthcare provider will probably give you specific instructions. Follow them carefully.