Catecholamine Metabolites

Catecholamine metabolites represent the most sensitive and specific tumor markers. While the determination of vanillylmandelic acid (VMA) and ho-movanillic acid (HVA) in a clean void urine sample is considered essential, the additional value of dopamine is less clear. The simultaneous measurement of urinary creatinine permits reliable VMA and HVA estimates in spot urine samples avoiding the uncomfortable 24-h urine collection. The determination of VMA, HVA, and dopamine in serum samples may be useful in some instances, but is 10-15% less sensitive. The usefulness of catecholamine metabolites as early markers of recurrence may be limited. In one study only 54% of patients demonstrated abnormal values at the time of recurrence (Simon et al. 2003). Using HPLC or mass spectrometry, the number of false-positive values is substantially reduced. False positives (predominantly HVA levels) were observed during a large screening program after massive apple juice intake, with active neurodermatitis, and with some congenital neurodevelopmental disorders. The ratio VMA/HVA as an indicator for prognosis has been diminished by the advent of new molecular markers, while the clinical utility of the dynamical response of tumor markers to treatment is just emerging (Hero et al. 2001).

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