Enzyme immunoassay for intact human insulin in serum or plasma

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 39; no. 4; pp. 578 - 582
• Main Authors: Andersen, L, Dinesen, B, Jorgensen, PN, Poulsen, F, Roder, ME
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.04.1993; American Association for Clinical Chemistry
• Subjects: Adult; Antibodies, Monoclonal; Biological and medical sciences; Diabetes Mellitus, Type 2 - blood; Endocrinology; Humans; Immunoenzyme Techniques - statistics & numerical data; Insulin - blood; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Quality Control; Reference Values; Human; Plasma; Correlation; Monoclonal antibody; Enzyme immunoassay; Non insulin dependent diabetes; Insulin; Protein hormone; Laboratory investigations; Radioimmunoassay; Clinical biology; Serum; Quantitative analysis
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1093/clinchem/39.4.578

We describe an enzyme-linked two-site immunoassay for quantitation of intact insulin in human serum and plasma. The method uses two murine monoclonal antibodies that bind to two different epitopes on the insulin molecule. The immunoassay is specific. Human proinsulin is not bound by the antibodies, and the binding of partially processed proinsulin intermediates is believed to be of minor clinical importance. The relative response of human, bovine, and porcine insulin is 1, 1, and 3, respectively. The assay is sensitive (detection limit 5 pmol/L), accurate (101% recovery with 50 pmol/L insulin added to samples, 95% with 100 pmol/L, and 89% with 300 pmol/L), and fast (results within 3 h), and has a high analytical capacity (done in microtiter plates). The working assay range selected is 5-600 pmol/L, corresponding to a clinically useful range. Because of its specificity, this two-site immunoassay gives results that are lower than those obtained by using a competitive radioimmunoassay, both in normal individuals and in non-insulin-dependent diabetics.