The addition of dopamine determination to the measurement of acidic catecholamine metabolites in urine screening for neuroblastoma

Abstract

Introduction: Urinary dopamine (DA) is well-known as a useful marker in the detection and follow-up of neuroblastomas, especially advanced cases. We have established a new method based on the simultaneous measurement of urinary DA and acidic catecholamine metabolites using high performance liquid chromatography (HPLC). The method described here has been applied in a regular neuroblastoma screening at age 6 months and in a second pilot screening at age 14 moths in Sapporo. Methods: Urine samples were taken from either dried specimens on filter paper or acidified 24-h urine specimens collected at a hospital. The analytical column used was an Inertsil ODS-2. N-octanesulfonate salt as an ion-pair reagent was added in the mobile phase. A coulometric detector with dual electrodes was utilized so that dopamine and other acidic catecholamine metabolites could be monitored on each electrode separately. Results: DA, vanillylmandelic acid (VMA) and homovanillic acid (HVA) were eluted at 9.9, 3.5 and 13.5 min, respectively. Samples were injected into the column every 15.5 min. Urinary DA was detectable between the range of 1.5 ng/ml and 5 μg/ml. Of 41809 infants who tested negative or did not participate in the first neuroblastoma screening and who received screening at age 14 months, we detected two neuroblastoma cases. Urinary DA levels were within normal limits in both. Conclusion: Measurement of urinary DA in addition to VMA and HVA was described. The method could be useful to reduce the likelihood of missing a patient who may develop neuroblastoma, even advanced or dopaminergic cases, though a pilot study using this assay could not prove the possibility yet.