Assessment of the diurnal variations in urinary homovanillic and vanillylmandelic acid excretion for the diagnosis and follow-up of patients with neuroblastoma.

The diurnal variation of urinary homovanillic acid (HVA) and vanillylmandelic acid (VMA) was studied in neuroblastoma patients and in a control group. Urinary HVA and VMA levels in four sequential 6-hour urine collections within a 24-hour period were compared. HVA and VMA levels were expressed in microgram/mg of urinary creatinine (UCr) and in mg/6h specimens. No statistically significant variations between the four time intervals were found when expressed in microgram/mg UCr or mg/6h. The small variations that exist in the excretion of HVA and VMA during different periods of the day are due to variations in renal excretion rather than variations in production. The results from this study indicate that a random urine sample should be as good as a 24-hour collection for diagnosis and follow-up of neural crest tumors.