[Diagnostic localization of insulinoma and prognostic value of postoperative glycemia monitoring].

Background: Our purpose was to establish the efficacy of different diagnostic tests for the diagnosis and localization of insulinoma as well as the prognostic value of postoperative glycemia measurements.

Patients And Method: Retrospective analysis of all insulinoma patients diagnosed at our hospital over the last fifteen years. Every patient underwent a supervised prolonged fasting and localization imaging tests were performed in positive cases. In the immediate preoperative period, during surgical intervention and immediately after it, an intravenous dextrose solution (10% concentration, 2-3 g/Kg/d infusion rate) was used to avoid hypoglycemia. Glycemia was measured every 6-8 h from the immediate postoperative period until hospital discharge.

Results: Seventeen insulinoma cases were identified (incidence 2.5 cases/million/year), 59% women and 41% men. The sensitivity (and positive predictive value) of diagnostic tests was: conventional-contrast CT scan 30% (75%), spiral CT scan 71.42% (100%), arteriography 28.57% (100%) and intraoperative ultrasonography 100% (100%). MRI identified insulinoma in two out of five patients and In-pentetreotide scintigraphy only in one out of five. Patients subsequently developing diabetes mellitus or glucose intolerance had higher levels of postoperative glycemia, which also lasted for more days, and longer need for insulin therapy. However, patients with a recurrence of the tumor did not show rebound hyperglycemia at all.

Conclusion: Postoperative glycemia could be a useful prognostic factor in patients who develop diabetes mellitus or glucose intolerance after resection of insulinoma and to predict insulinoma recurrence.