CLINICAL AUDIT - THE CLINICAL AND LABORATORY CORRELATES OF AN INCREASED URINARY 5-HYDROXYINDOLEACETIC ACID

Over a live-and-a-half-year period, there were 298 laboratory requests for urinary 5-hydroxyindoleacetic acid (5-HIAA). The clinical and lab oratory associations of the 24 patients in which there were 43 urinary 5-HIAA 24-h collection results greater than the laboratory upper refe rence limit are detailed. Four were confirmed carcinoid tumours and tw o were phaeochromocytomas. Flushing was a prominent symptom in 46% and diarrhoea or altered bowel habit in 37%. Associated with the raised u rinary 5-HIAA values were increased levels of 4-hydroxy-3-methoxymande lic acid and homovanillic acid in 14.3% and 21%, respectively, of thos e collections where the metabolites were requested. Diagnostic imaging was performed in 57%. While the specificity was 88%, 5-HIAA is relati vely insensitive in the diagnosis of carcinoid tumours and a more wide spread use of diagnostic imaging including isotope scanning with label led metaiodo-benzylguanidine, vasoactive intestinal peptide and octreo tide is suggested.