Insulin assay

In evaluating different assay systems it is convenient to use a table of B/Bq vs dose. By comparing these values for different assays a comparison of the sensitivity of the assay can be made. Thus an insulin assay with 50% binding at a concentration of 40 microunits would show much more sensitivity than an assay with a 30% binding occuring at 100 microunits, since the more the dose is lowered, the greater the percent binding becomes. 

Kato, K., Hamaguchi, Y., Fukui, H., and Ishikawa, E. (1975a) Enzyme-linked immunoassay. I. Novel method for synthesis of the insulin-b-D-galactosidase conjugate and its applicability for insulin assay. /. Biochem. (Tokyo) 78, 235. 

Typical standard curve for competitive insulin assay. 

Fig. 1. Dose-response curve for amount of dextran-coated charcoal added versus percentage free and bound, adsorbed. These are theoretical curves drawn from generalizations derived from several assays. —, Curve showing binding of free ligand —, curve showing binding of antibody bound ligand. The exact amounts of charcoal giving a particular bound value vary with each assay (e.g., growth hormone assay differs from insulin assay). For significance of arrows A and B, see the section on selection of charcoal dose.

Diagnosis of p-cell tumors Familial hyperproinsulinemia Cross-reactivity of insulin assays... 

Although insulin has been assayed for more than 40 years, there is no highly accurate, precise, and reliable procedure available to measure the amount of insulin in a patient sample. Many insulin assays are commercially avaEable. The techniques most widely used in the United States are immunochemical. Bioassays, although of greater physiological relevance because they measure biological activity, are labor intensive and not widely used. A stable isotope dEu-... 

Acceptance criteria for an insulin assay are less than 15% interassay CV. Minimum detectable concentration of insulin, as calculated from the calibration curve, should be 1 pIU/mL with the overnight procedure or 3 pIU/mL with the same-day procedure. In addition, recovery and linearity should be 100 15%, and the in-house insulin calibrator should be within 5% of the gold standard. No gold standard was specified. 

Robbins DC, Andersen L, Bowsher R, Chance R, Dinesen B, Frank B, et al. Report of the American Diabetes Association s Task Force on standardization of the insulin assay. Diabetes 1996 45 242-56. 

Human T-cell lymphotrophic virus Immunoglobulin electrophoresis Insulin antibody Insulin assay... 

Chevenne, D., F. Trivin, and D. Porquet. 1999. Insulin assays and reference values. Diabetes Metabolism (Paris) 25 459 76. 

Sapin, R., Galudec,V.L., Gasser, F., et al. (2001) Elecsys insulin assay Free insulin determination and the absence of cross-reactivity with insulin lispro. Clinical Chemistry, 47,602-605. 

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