Anatomy => Radioimmunoassay
Radioimmunoassay, in biochemistry and medicine, a technique for quantifying minutely small amounts of biological substances such as enzymes, hormones, steroids, and vitamins in blood, urine, saliva, or other body fluids. Radioimmunoassay was developed in the 1950s by the American physician Solomon Aaron Berson and the American medical researcher Rosalyn Sussman Yalow; Yalow received the Nobel Prize in physiology or medicine for this achievement in 1977.
A radioimmunoassay, or RIA, requires three materials: a radioactively labeled preparation of the substance to be measured, antibody to this material, and a biological fluid containing an unknown amount of the material. For example, to measure the amount of insulin in a blood sample-the first medical application of RIA-a radioactively labeled solution of insulin is mixed with antiinsulin antibody. The amount of insulin that binds to the antibody is determined by counting the amount of radioactivity combined with the antibody. To measure the amount of insulin in the blood sample, a small amount of the blood is mixed with the labeled insulin and the antiinsulin antibody. The amount of insulin in the blood sample is shown by the decrease in the amount of radioactive insulin bound to the antibody. The RIA is now an important research tool, as well as being commonly used in hospitals to help diagnose diabetes, thyroid disorders, hypertension, reproductive problems, and other diseases.