This assay employs the competitive inhibition enzyme immunoassay technique. The microtiter plate provided in this kit has been pre-coated with an antibody specific to 5-HIAA. Standards or samples are added to the appropriate microtiter plate wells with Biotin-conjugated 5-HIAA. A competitive inhibition reaction is launched between 5-HIAA (Standards or samples) and Biotin-conjugated 5-HIAA with the pre-coated antibody specific for 5-HIAA. The more amount of 5-HIAA in samples, the less antibody bo