Rapid measurement of insulin using the Abbott IMx: application to the management of insulinoma

Background Patients with multiple endocrine neoplasia (type 1) often present with multiple pancreatic endocrine tumours, such as insulinomas. A major difficulty in the surgical treatment of such patients is identifying which tumours are functionally active and therefore need to be resected for a cure. The objective of this study was to develop a rapid insulin assay that could be used intraoperatively for identifying insulinomas from pancreatic aspirates. Methods By reducing the incubation time and by increasing the sample volume, a rapid insulin assay was developed on the IMx analyser. This was used to measure insulin from tissue aspirates collected from suspected insulinomas under ultrasound guidance. Results The rapid insulin assay (y) could be performed in 14 min and showed a good correlation with the standard IMx (x) insulin assay (y = 0.808x + 0.04; r(2) = 0.986). Using the rapid insulin assay on pancreatic tissue aspirates, insulinomas could be readily distinguished from normal pancreatic tissue or from non-functional adenomas based on a marked increase in insulin content. Conclusion In summary, a new rapid assay for insulin is described that compares favourably to the standard IMx insulin assay and can potentially be used intraoperatively on pancreatic aspirates for identifying functionally active insulinomas.