Radioimmunoassay of insulin.

The powerful nuclear medicine tool of radioimmunoassay was very rapidly developed because of the favorable properties of insulin in such a procedure. The current method of insulin immunoassay in our laboratory is described, with emphasis on the details of the separation of bound and free using talc tablets; emphasis is also given to the correction for tracer damage. The clinical usefulness of the insulin radioimmunoassay is somewhat less than had been anticipated, although its use as a research tool has had immeasurable impact upon the study of metabolism. The presence of proinsulin in plasma is a factor that has to be considered during the radioimmunoassay. Radioimmunoassays for the connecting peptide of proinsulin have also been developed. A preliminary evaluation of two radioimmunoassay kits is described.