| homovanillic acid | A test that measures the level of catecholamines or their metabolites in the urine. A 24 hour urine sample is necessary for this assay. Elevations may be seen in pheochromocytoma or neuroblastoma. Normal urine levels of adrenaline should be: 0.5 to 20 mcg/ml and normal urine levels of noradrenaline should be 15 to 80 mcg/ml. (27 Sep 1997) |
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| homovanillic acid test | A test for homovanillic acid based upon the fact that dopamine is present in sympathetic nervous tissue as precursor of norepinephrine; since norepinephrine has a metabolic pathway which yields homovanillic acid, tumours such as neuroblastomas and ganglioneuromas may cause elevations of urinary dopamine and homovanillic acid. Synonym: HVA test. (05 Mar 2000) |