Radio Immuno Assay (RIA):
- Radioimmunoassay is an analytic technique which is used from the last many years.
- Here, the molecule which is to be analysed, which acts as an antigen is marked with a radiolabelled substance.
- The labelled and normal antigen molecules are allowed to react with a specific antibody.
- A comparative analysis of the reaction is done. In this technique, the radioisotope is used as a marker molecule.
- This technique was invented by Rosalyn and Yalow. Now – a – days it has become an important diagnostic technique.
- This is especially important for the analysis of those biochemical factors that are present in very minute concentration (microgram, nanogram or picogram) and cannot be analysed by the traditional gravimetric and volumetric processes.
- The radioisotopes used in radioimmunoassay are high specificity molecules, which provide very high sensitivity to this technique.
- In this technique, the standard solution of different concentration of normal molecules of the substance to be analysed is used with the solutions of the radiolabelled substance of similar concentrations.
- This mixture is allowed to react with antibodies. At the stage of equilibrium, antigen-antibody complexes are absorbed by the suitable reagent.
- The precipitated and supernatant parts are separated and by measuring the radioactivity, the concentration of the substance is estimated.
- A major characteristic of Radio Immuno Analysis is that the patient does not suffer from any side effect.
- He is never treated with the radioisotopic molecule because the whole process is executed outside the body.