Urinary catecholamine metabolites (VMA and HVA)

What is measured: vanillylmandelic acid and homovanillic acid, the breakdown products of noradrenaline and dopamine. How: a spot or 24-hour urine sample analysed by liquid chromatography with mass spectrometry, normalised to creatinine against age-specific ranges; raised in about 90 percent of neuroblastomas, more often in metastatic disease and less in MYCN-amplified or undifferentiated tumours, where a low VMA to HVA ratio points to a less differentiated tumour. Plasma or urine metanephrines are the preferred equivalent for phaeochromocytoma and paraganglioma. What a result changes: with imaging and marrow findings, raised metabolites and a compatible mass can establish the diagnosis when a biopsy is dangerous, although the INRG system still requires tissue for biology; the markers are part of the International Neuroblastoma Response Criteria, are followed every few months during and after treatment, and warn the anaesthetist of a catecholamine-secreting tumour before surgery. Infant screening programmes in Japan, Germany and Quebec found mostly tumours that would have regressed and did not reduce deaths, so they were stopped. Where it matters: neuroblastoma and its risk-group pages.