294 Technical Validation of Insulin Immunoassay for Cross-Reactivity of Animal Insulins

Introduction/Objective A critical element in the workup of patients with hypoglycemia is the ability to detect and discern both endogenous and exogenous insulin in a patient’s serum. Automated immunoassays used in clinical laboratories have variable abilities to detect human insulin analogues. There is no current literature on the ability of these immunoassays to detect pet insulin formulations, which are often of similar composition to human formulations. Pet insulin may be an easy-to-access, inexpensive source of insulin to be improperly administered in cases of factitious disorders. As such, the ability to detect these formulations by clinical immunoassays should be explored. Methods/Case Report To assess this ability, we pooled residual human serum with normal insulin values from our clinical laboratory and performed spiking experiments with three different concentrations each of two commonly utilized veterinary insulins: Prozinc (Boehringer Ingelheim, Duluth, GA) and Vetsulin (Merck Animal Health, Rahway, NJ). These samples were then analyzed on three common insulin immunoassays: Beckman (Beckman Coulter, Inc., Brea, CA), Siemens (Siemens Medical Solutions, Inc., Malvern, PA), and Roche (Roche Diagnostics, Indianapolis, IN) platforms. Results The results demonstrated comparable levels of Prozinc insulin detected for negative control, low, medium, and high concentrations across each of the analyzers. However, the levels of Vetsulin detected by Roche were consistently lower than the other analyzers. Conclusion This discrepancy is an important contribution to the characterization of insulin profiles across detection systems.