Diagnosis and localization of an insulinoma with inappropriate hypoglycemia in relation to the level of immunoreactive insulin using gel chromatographic separation.

We evaluated the possibility to diagnose the case of insulinoma using the combination of portal blood sampling and gel filtration techniques. The portal blood sampling showed 52 muU/ml of immunoreactive insulin (IRI) level at the closest splenic vein to the tumor, but the level should not be high enough to reasonalize the being of the tumor. The gel filtration pattern of IRI from the blood at the same point was clearly different from the other samples. Therefore, it could be useful for the diagnosis of insulinoma to combine percutaneous transhepatic portal blood sampling and gel filtration in such a case.