A method for the immunoassay of insulin in the presence of insulin therapy-induced antibody.

Antibodies produced by exogenous insulin therapy interfere with the measurement of immunoreactive insulin (IRI) by conventional methods. A modified acid-alcohol extraction method is described which allows for accurate measurement of total IRI in the plasma of insulin-treated patients. Total extractable IRI includes both IRI bound to antibody and free IRI. Free IRI can be separated from antibody-bound IRI by Sephadex G-50 chromatography. The amount of insulin bound to antibody is calculated as the difference between total extractable IRI and the free IRI. The accuracy of these methods is demonstrated by recovery experiments. Suggested applications of these techniques to clinical states are offered.