Rapid radioimmunoassay for insulin and its application in localizing occult insulinomas by intraoperative pancreatic vein catheterization.

A rapid RIA for insulin and its application to localising occult insulinomas during surgical exploration is described. A standard curve and twelve serum samples can be assayed within 45 min. The assay is equivalent with respect to accuracy and precision to conventional RIAs for insulin. Pancreatic vein catheterisation at laparotomy and immediate insulin determination made it possible to localize and resect two insulinomas which were not demonstrated by arteriography, computed tomography, ultrasound, and not palpable at surgery. We suggest that the new technique will end the long controversy concerning subsequent management of occult insulinomas.