Establishment of cut off values for vanillylmandelic acid and homovanillic acid in 24-hr urine accumulation during mass screening for neuroblastoma.

The establishment of cut off values in vanillylmandelic acid (VMA) and homovanillic acid (HVA) in 24-hr urine specimens for the purpose of separating true positive cases from normal infants has been discussed. The specimens were collected at the time when thorough examinations under a mass screening programme for neuroblastoma were taking place, and data from 17 infants with neuroblastoma (patients) and 50 healthy infants (controls) have been employed. The function square root VMA2 + HVA2 = 34 (micrograms/mg of creatinine) separated the two groups with no overlapping cases. This function represents the distance from the origin of the VMA-HVA co-ordinates, and is thought to be one of the most reasonable discriminant methods when considering the distribution pattern of the data for normal cases and patients.