Vanillylmandelic Acid (VMA) (24 Hrs Urine)

Specimen Required

24 Hrs Urine

Fasting Required

Purpose of the Test

The Vanillylmandelic Acid (VMA) test is ordered to evaluate the levels of catecholamines in the body, mainly epinephrine, norepinephrine, and dopamine. It is used to diagnose and monitor neuroblastoma, a type of cancer that occurs mainly in children. The test can also help in the diagnosis and monitoring of other rare tumors that secrete catecholamines.

When this test is required

The VMA test is requested when a patient has symptoms of neuroblastoma or other catecholamine-secreting tumors, such as high blood pressure, sweating, rapid heartbeat, or anxiety. It may also be requested as a follow-up test to monitor the effectiveness of treatment.

What the Test Detects

The VMA test measures the levels of vanillylmandelic acid in a 24-hour urine sample. Vanillylmandelic acid is a breakdown product of catecholamines, such as epinephrine, norepinephrine, and dopamine, which are produced by the adrenal glands and certain nerve cells. An increase in the levels of VMA in the urine indicates an increased production of catecholamines, which may be due to neuroblastoma or other tumors that secrete these hormones.

Preparation for the Test

There are no specific test preparations required for the VMA test. However, patients should avoid foods and drinks that can affect catecholamine levels, such as caffeine, tea, chocolate, and some medications. The doctor will provide specific instructions before the test.

Sample Requirements

The VMA test requires a 24-hour urine collection. The patient will need to collect all urine during a 24-hour period, which is usually started in the morning after the first urine void. The sample is then sent to the laboratory for analysis.

Additional Notes

The VMA test is a useful tool in the diagnosis and monitoring of neuroblastoma and other catecholamine-secreting tumors. However, it is important to remember that the test is not specific for neuroblastoma, and a positive test does not confirm the diagnosis. The doctor will evaluate the test results along with other tests, such as urine and blood tests, imaging studies, and a biopsy, to confirm the diagnosis.

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