Serum/plasma concentration of dopamine metabolites (homovanillic acid and vanillylmandelic acid) measured by high-performance liquid chromatography (HPLC)

What This Test Measures

The test detects two key dopamine metabolites: homovanillic acid (HVA) and vanillylmandelic acid (VMA). These compounds are produced when dopamine is broken down in your body. The HPLC method separates and quantifies these substances in your serum or plasma sample.

Why It’s Ordered

Your healthcare provider may order this test if you have symptoms linked to dopamine imbalances, such as movement disorders (e.g., Parkinson’s disease), neurological conditions, or suspected pheochromocytoma (a rare tumor affecting hormone production). It may also be used in research or specialized clinical scenarios.

Sample Collection and Preparation

A blood sample is drawn from a vein, typically in your arm. The blood is processed to separate serum or plasma, which is then analyzed in a lab using HPLC. This process usually takes a few hours, and results are reported as concentrations of HVA and VMA.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to avoid certain medications (like certain antidepressants) for 24 hours before testing, as they could affect dopamine levels. If you have a history of bleeding disorders or are on blood thinners, let your provider know.