homovanillic acid test

ho·mo·va·nil·lic ac·id test

a test for homovanillic acid based on the fact that dopamine is present in sympathetic nervous tissue as precursor of norepinephrine; because norepinephrine has a metabolic pathway that yields homovanillic acid, some tumors (for example, neuroblastomas and ganglioneuromas may cause elevations in levels of urinary dopamine and homovanillic acid.
Synonym(s): HVA test