LACK OF UNIFORMITY IN THE CLINICAL APPROACH TO THE INTERPRETATION OF URINARY CATECHOLAMINES AND THEIR METABOLITES

A study of the case notes from 101 of the 113 instances where at least one of the results was abnormal from the analysis of 24 hr urinary co llections for noradrenaline, adrenaline, and dopamine and their metabo lites 4-hydroxy-3-methoxy-mandelic acid (HMMA) and homovanillic acid ( HVA) in screening for phaeochromocytomas in hospitals affiliated to th e Royal College of Surgeons in Ireland Medical School from a total of 199 false positives from all sources shows that 51% had a second sampl e, 33% had ultra sound, 12% had a CT scan, 6% had an 131-I metaiodoben zylguanadine (MIBG) scan, 40% had no imaging performed and in 5% the r eports were not received by the referring medical team. The 12 sets of data where case notes could not be retrieved were disregarded. Of the 22 patients with one or more biochemical value greater than twice the upper reference range, 8 had not, by our criteria had a phaeochromocy toma positively excluded. The sensitivity and specificty for phaeochro mocytoma diagnosis for the free catecholamines together was 82% and 88 .4%; for HMMA 60% and 95.8%; and for catecholamines and HMMA together 82% and 93.2% respectively. A protocol which includes repeat samples w here results are abnormal and the appropriate use of diagnostic imagin g should be systematically pursued to minimise false negative diagnose s.