Serum or plasma substance concentration (mass concentration) for urinary vanillylmandelic acid (VMA)

Why is this test done?

Your healthcare provider may order this test to check for conditions like pheochromocytoma (a tumor affecting hormone production), neuroblastoma (a childhood cancer of nerve tissue), or other adrenal or nervous system disorders. It’s often used alongside other tests to diagnose or monitor these conditions.

What does the test involve?

You’ll collect all your urine for a full 24-hour period, starting after you wake up the morning of the test and ending just before you wake up the next morning. The urine is then sent to the lab for analysis. Some tests may also require a blood sample for comparison.

What should you expect during or after the test?

You’ll need to keep a detailed record of your urine output, including the time and any unusual colors or substances. Drink plenty of water to help flush your system, but avoid caffeine or alcohol, as they can affect results. Follow your provider’s instructions carefully to ensure accuracy.

How does this test differ from a blood test for VMA?

While blood tests can measure certain hormone-related substances, a 24-hour urine VMA test specifically captures the total breakdown product of hormones over a full day, giving a more comprehensive picture of long-term hormone activity in your body.