Quantitation of free, total, and antibody-bound insulin in insulin-treated diabetics.
We describe a simplified method for measuring free, total, and antibody-bound insulin in insulin-treated patients in whom antibodies to insulin are present. The free, active insulin is extracted from the serum with a polyethylene glycol solution. Total insulin is extracted from the serum with a polyethylene glycol solution after dissociation of the antibody-antigen complex with dilute HCI. Aliquots of the extracts are used in the radioimmunoassay system. The figure for antibody-bound insulin is the difference between the total and free insulin values and reflects the concentration of insulin antibodies present. A commercially available ("Phadebas") radioimmunoassay for immunoreactive insulin was used to quantitate the insulin present in the two extracts. Recovery of added insulin averaged 85% for the free insulin and 87%for the total insulin.
D000936:Antigen-Antibody Complex; D003920:Diabetes Mellitus / Q000188:drug therapy*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000097:blood* / Q000627:therapeutic use; D007330:Insulin Antibodies / Q000032:analysis; D011485:Protein Binding; D011863:Radioimmunoassay / Q000379:methods*; D014044:Tolbutamide / Q000494:pharmacology
D000936:Antigen-Antibody Complex; D007328:Insulin; D007330:Insulin Antibodies; D014044:Tolbutamide