system
Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
Most sensitive test for antigen detection is -
assistant
The correct answer is  RIA is a competitive binding assay in which fixed amounts of antibody and radiolabelled antigen react in the presence of unlabeled antigen. The labeled and unlabeled antigens compete for the limited binding sites on the antibody. This competition is determined by the level of the unlabelled antigen present in the patient's serum sample. Reference : Anathanarayan & paniker's 9th edition, pg no:113 <\p>