Determination of urinary homovanillic acid using the nitrosonaphthol reaction.

Determination of urinary homovanillic acid (HVA) is an important analysis to establish the diagnosis and prognosis of neuroblastoma. A method is presented for the determination of this metabolite of dopamine using its reaction with 1-nitroso-2-naphthol and nitrous acid. The method has shown a sensitivity, specificity, positive predictive value, negative predictive value, and efficiency of 100%, 97.4%, 92.3%, 100%, and 98%, respectively. In the last two years, four new cases of neuroblastoma have been diagnosed, with the use of this method, one of which has no increase in the concentration of urinary vanillylmandelic acid.