5-HIAA ELISA (5-Hydroxyindole acetic acid)

Enzyme immunoassay for the in-vitro-diagnostic quantitative determination of 5-HIAA in human urine. The primary carcinoid tumor is usually derived from the enterochromaffin cells of the midgut and is located most frequently in the terminal ileum. Carcinoid tumours generally secrete various amounts of indoles. The carcinoid syndrome is generally characterized by an increased urinary excretion of 5-hydroxy-3-indole acetic acid (5-HIAA), the end product of serotonin (5-HT) metabolism. Traditionally, 5-hydroxy-3-indole acetic acid is assayed by diazotization with nitrosonaphtol to form a purple colour. However, it is well documented that many other substances present in the urine interfere with this reaction to give false-positive results. Attempts were made to overcome this problem by a com¬bination of ion exchange chromatography and fluorometry. These methods, however, lack sensitivity and are time consuming. Recently, high performance liquid chromatographic analyses of 5-HIAA with fluorometry in the ultraviolet region of the spectrum or electrochemical detection have been described. Both methods require solvent extraction because of the numerous interfering compounds present in urine. The 5-HIAA enzyme immunoassay is a new and simple method for the quantification of this important marker of carcinoid syndrome in small urine samples.