THE HIGHWAY TO INSULINOMA - ROAD SIGNS AND HAZARDS

Insulinomas are rare tumors that may present a diagnostic dilemma to t he clinician. The classic diagnostic test for this disorder is the sup ervised 72-hour fast. The presence of inappropriately elevated plasma insulin and plasma C-peptide levels at the time of symptomatic hypogly cemia in a sulfonylurea-negative patient establishes the diagnosis. In most cases of insulinoma the results of the 72-hour supervised fast a re unequivocal. When beta cell polypeptide levels are inconclusive, ho wever, determination of markers of insulin action, such as plasma beta -hydroxybutyrate and plasma glucose response to intravenous glucagon a t the end of the fast, may provide additional diagnostic information, The cases described herein highlight some of the difficulties that may be encountered during the evaluation of suspected and the management of biochemically confirmed insulinoma and provide clues that lead to a correct diagnosis and therapy.