Secular Trends in the Presentation and Management of Functioning Insulinoma at the Mayo Clinic, 1987–2007

Abstract

Objective The objective of the study was to assess changes in the presentation and diagnostic and radiological evaluation of patients with surgically confirmed insulinoma at the Mayo Clinic 1987-2007. Methods A retrospective analysis of patients with insulinoma was conducted. Patients with prior gastric bypass were excluded. Results A total of 237 patients [135 women (57%)] were identified. Hypoglycemia was reported solely in the fasting state in 73%, the fasting and postprandial state in 21%, and exclusively postprandially in 6%. There was a predominance of men in the postprandial symptom group. Considering the period of study by quartile, outpatient evaluation increased from 35 to 83% and successful preoperative localization improved from 74 to 100% comparing the first to the fourth quartiles. Although the rates of localization by noninvasive techniques remained static at approximately 75%, the addition of invasive modalities has resulted in successful preoperative localization in all patients in the past 10 yr. The sensitivity and specificity of the established diagnostic criteria using insulin, C-peptide, proinsulin, beta-hydroxybutyrate, and glucose response to iv glucagon were greater than 90% and greater than 70%, respectively. Conclusions Although fasting hypoglycemia is characteristic of patients with insulinoma, postprandial symptoms have been reported with increasing, albeit low, frequency. Trends in the evaluation and preoperative management include a shift to out…