Final answer:
The Radial Immunodiffusion Assay (RID) helps to confirm the diagnosis of IDA by quantifying antigen concentration using a zone of precipitation.
Step-by-step explanation:
The assay that helps to confirm the diagnosis of Iron Deficiency Anemia (IDA) is the Radial Immunodiffusion Assay (RID) . This assay is used to quantify the concentration of antigens and antibodies. In the RID assay, antiserum is added to agar and wells are cut in the agar. Antigen is then added to the wells and allowed to diffuse, forming a zone of precipitation. The size of the zone of precipitation is directly proportional to the concentration of antigen, which can be measured to determine the concentration of an unknown solution.