Insulin assays were performed on tissue extracts from ten nonpancreatic tumors and five islet-cell adenomas, all of which were associated with hypoglycemia. Acid alcohol and normal saline extractions were made from tumor tissue as well as from normal tissue. The insulin content of extracts was determined both biologically and immunologically, utilizing the rat epididymal fat pad to measure insulinlike activity (ILA) and the double antibody radioimmunoassay to estimate insulin (IRI).
All five islet-cell adenomas were found to have significant concentrations of biologically and immunologically active insulin. The nonpancreatic tumors had no significant concentration of insulin or insulinlike activity, but results were equivocal in one hepatoma. The mechanism by which such tumors induce hypoglycemia remains unknown. It does not appear to result from the elaboration of insulin or of products with insulinlike activity.