Fluctuation in the concentrations of vanillylmandelic acid and homovanillic acid in mass screening for neuroblastoma.

Fluctuations in the amount of vanillylmandelic acid (VMA) and homovanillic acid (HVA) were studied in random urine samples from 13 infants with neuroblastoma. In patients with a small tumour, many samples contained amounts below the cut off values, suggesting that detection of a patient with neuroblastoma depended on mathematical probability. Using high performance liquid chromatography a patient with a tumour of about 10 g may well be overlooked, whereas a patient whose tumour weighs over 30 g would probably be detected. With qualitative screening, although more likely to miss a patient with low VMA excretion, a patient with a tumour weighing over 50 g would be detected. In a thorough hospital examination care should be exercised in interpreting borderline values of VMA and HVA; excretion information suggesting the existence of a tumour may aid localization by radiological imaging procedures.