Which specimens are commonly used for measuring HVA/VMA by HPLC?

• A. Serum only
• B. Urine (24-hour) or plasma
• C. Cerebrospinal fluid
• D. Whole blood

Answer: (B)

HVA and VMA are metabolites of catecholamines that appear in urine over time, so measuring them with HPLC relies on collecting a sample that reflects daily excretion. A 24-hour urine collection provides a complete picture of how much of these metabolites the body eliminates in a day, which reduces the impact of day-to-day fluctuations and yields enough material for precise HPLC analysis. Plasma measurements are possible in some settings, but they’re less stable and more variable because metabolite levels can change quickly and are typically present at lower concentrations. That makes urine over a full day the preferred specimen for routine HVA/VMA testing, with plasma serving as an alternative only in specific situations.