What is Urine Metanephrines Test?

Urine metanephrines test is used to check for a rare type of adrenal gland tumor called a pheochromocytoma. These tumors are usually not cancerous (are benign), but they create excess hormones that can cause symptoms.

You may have this test if you have been treated for a pheochromocytoma or if you have symptoms of having one. These symptoms include:

• High blood pressure.
• Headaches.
• Rapid heartbeat.
• Sweating.

What is being tested?

This test measures the amount of metanephrines in your urine. Metanephrines are substances that result from the breakdown of two hormones, epinephrine and norepinephrine. These hormones are made by your adrenal glands, which are located on top of your kidneys. Adrenal glands release these hormones during times of stress. After they are released, the hormones break down into metanephrine and normetanephrine and leave your body in your urine.

It is normal to find a small amount of metanephrines in urine. However, if you have a large amount of metanephrines in your urine, this can be a sign of a pheochromocytoma tumor.

What kind of sample is taken?

A urine sample is required for this test. Your health care provider will give you a container to collect all the urine you produce over 24 hours.

How do I collect samples at home?

You may be asked to collect a urine sample at home over a 24-hour period. Follow instructions from a health care provider about how to collect the sample.

When collecting a urine sample at home, make sure you:

• Use supplies and instructions that you received from the lab.
• Collect urine only in the germ-free (sterile) cup that you received from the lab.
• Do not let any toilet paper or stool (feces) get into the cup.
• Refrigerate the sample until you can return it to the lab.
• Return the samples to the lab as instructed.

How do I prepare for this test?

Many medicines, some foods, and heavy exercise can increase urinary metanephrines.

• Let your health care provider know about all medicines you are taking, including vitamins, herbs, eye drops, creams, and over-the-counter medicines. You may need to stop taking them before the test.
• Do not exercise heavily before or during the testing period as told by your health care provider.
• Follow instructions from your health care provider about what foods or drinks you should avoid before and during the test.

How are the results reported?

Your test results will be reported as values. Your health care provider will compare your results to normal ranges that were established after testing a large group of people (reference ranges). Reference ranges may vary among labs and hospitals. For this test, common reference ranges are:

• Metanephrine: Less than 1.3 mg/24 hr or less than 7 μmol/day (SI units).
• Normetanephrine: 15–80 mcg/24 hr or 89–473 nmol/day (SI units).

What do the results mean?

Abnormally high levels of metanephrine and normetanephrine may mean:

• You have a pheochromocytoma.
• A previous pheochromocytoma has returned after treatment.

Abnormally high levels could also mean that your test result was a false positive. This happens when something else causes your metanephrines to go up. Stress or certain medicines can make this happen. Your health care provider may do more tests to confirm a diagnosis of pheochromocytoma.

If your test results are within the reference ranges, you are unlikely to have a pheochromocytoma.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• The urine metanephrines test is used to check for an adrenal gland tumor called a pheochromocytoma.
• Symptoms of this type of tumor include high blood pressure, elevated heart rate, excessive sweating, and headaches.
• False-positive results can occur. Your health care provider may do more tests to confirm a diagnosis of pheochromocytoma.
• If your test results are within the reference ranges, you are unlikely to have a pheochromocytoma.