Radioimmunoassay facts for kids

A radioimmunoassay (RIA) is a special type of immunoassay. This is a test that uses parts of the body's immune system to find and measure tiny amounts of substances. RIA uses molecules that have a small amount of radioactivity added to them. These "marked" molecules help scientists find and measure other substances.

RIA is a very sensitive test. This means it can find even very small amounts of a substance. It is often used to measure things like hormone levels in blood. For example, it can check how much of a certain hormone is in a patient's blood.

This method is very good at finding exactly what it's looking for. However, it needs special equipment and safety rules. This is because it uses tiny amounts of radioactive material.

A radioallergosorbent test (RAST) is one example of a radioimmunoassay. Doctors use RAST to find out what causes a person's allergy.

How the Test Works

To do a radioimmunoassay, scientists start with a known amount of a substance called an antigen. This antigen is made radioactive. Often, they use a radioactive form of iodine to mark it. This "hot" (radioactive) antigen is then mixed with a specific antibody. Antibodies are like tiny search-and-find tools made by the immune system. They stick only to certain antigens.

Next, a sample of blood serum from a patient is added. This serum contains an unknown amount of the same antigen. This patient's antigen is "cold" (not radioactive).

Now, the "cold" antigen from the patient's blood and the "hot" radioactive antigen compete. They both try to stick to the limited number of antibody spots. If there is a lot of "cold" antigen in the patient's blood, more of it will stick to the antibodies. This means less of the "hot" radioactive antigen will be able to bind.

After this competition, the antigens that are stuck to the antibodies are separated. Scientists then measure the radioactivity of the "hot" antigen that did not stick to the antibodies. By seeing how much "hot" antigen was pushed away, they can figure out how much "cold" antigen was in the patient's sample.

History of RIA

The radioimmunoassay method was created by two scientists. Their names were Solomon Berson and Rosalyn Sussman Yalow. They developed this important test at the Bronx Veterans Administration Hospital in the Bronx, New York.

This new discovery was very important for medicine. Because of her work, Dr. Yalow won the Nobel Prize for Medicine in 1977. She was only the second woman ever to win this prize. In her speech, Dr. Yalow talked about how important it is for everyone to use their talents. She shared the Nobel Prize with Roger Guillemin and Andrew Schally. They won for their research on hormones made by the brain.

See also

In Spanish: Radioinmunoensayo para niños