Basic Principle of RIA

This method evaluates or assays materials to determine the particles present that is otherwise unmeasurable or detectable only with difficulty. Competitive binding is the fundamental concept of radioimmunoassay, in which a radioactive antigen (“tracer”) competes with a non-radioactive antigen for a given number of antibody or receptor binding sites. When unlabeled antigen from standards or samples is allowed to react with a set amount of tracer (labelled antigen), decreasing quantities of tracer are bound to the antibody as the amount of unlabeled antigen is raised. In other words, the binding of the unlabeled antigen to the fixed and finite amount of antibody induces displacement of the radio-labelled antigen, which reduces the radioactivity of the antigen-antibody complex. RIA helps in determining the concentration of such labelled Molecules by measuring their radioactivity rather than by chemical analysis.

Applications of Radioimmunoassay

 This approach has a substantial influence on medical diagnosis because of the simplicity with which the tests may be performed while ensuring accuracy, specificity, and sensitivity.  Radioimmunoassay can be used to detect substances like Hormones, Vitamins, Serum Proteins, Infective agents and drugs. It can detect substances from a range of Nanograms (ng) to Pico gram(pg).

Types of RIA

Double-antibody RIA and coated-tube RIA are the two most prevalent RIA technologies used for drug detection in biological matrices.

Double Antibody RIA – A second antibody is added to double-antibody RIA to aid in the precipitation of the bound main antibody. The unbound labelled medication can be easily removed after the primary/secondary antibody-antigen complex precipitates. 

Coated-tube RIA – The primary antibody is coated on the interior of each tube in coated-tube RIA. By draining out the supernatant, the unbound labelled medication may be readily removed. 

Each RIA method’s samples are evaluated in a gamma counter to calculate the counts per minute, which are inversely proportional to the amount of drug contained in the original specimen. Radioimmunoassays are sensitive and specific, but they need particular handling and disposal of radioactive materials.

Advantages of Radioimmunoassay

The different advantages of radioimmunoassay are:

It is a very sensitive test that can detect antigens in picogram levels.

The antibody-antigen response is very specific. Hence the test is highly specific. Due to its high specificity, it can measure a single hormone in the presence of other hormones. 

RIA can be used to measure hormones in a variety of body fluids, including blood, urine, and saliva.

A vast number of samples can be processed, such as blood, urine and saliva.

It is an indirect analysis method.

Disadvantages of Radioimmunoassay

Radioimmunoassay has several disadvantages, such as:

This process requires highly specific activity-radiolabeled hormones, and a scintillation counter is required, and they might not be easily available. 

While carrying out this process, the testers need to be extremely careful as they will be handling radioactive compounds.

Because RIA is a sophisticated and time-consuming method, it is not appropriate for routine testing. RIA is also costly; the equipment and reagents necessary for RIA might be prohibitively pricey. Furthermore, because RIA is operated by qualified individuals, it is not usually available in many places, such as small hospitals and laboratories.

Related Links:

CSIR NET Question Paper	CSIR NET Admit Card
CSIR NET Books	CSIR NET Age Limit
CSIR NET Cut Off	CSIR NET Vacancy
CSIR NET Syllabus	CSIR NET Answer Key