Laboratory application of the dextran-coated-charcoal radioimmunoassay of insulin.

A modification of the method for radioimmunoassayof insulin is described, which achievessatisfactory sensitivity while employing commercially available reagents and antiserums. These modifications consist mainly in lowering the initial percentage binding, reducing the amount of labeled insulin, and preincubating the unlabeled hormone with antiserum. Application of the linear isotope dilution formula, modified for our conditions, proves to be a reliable substitute for the standard curve.