title: Assessment of suspected insulinoma by 48-hour fasting test: a retrospective monocentric study of 23 cases.
abstract: OBJECTIVE
  Insulinoma causes fasting hypoglycaemia due to inappropriate insulin secretion. The diagnosis of insulinoma is based on Whipple's triad during a supervised fasting test. The aim of our study was to evaluate retrospectively the percentage of positive 48-hour fasting tests in a large series of patients with insulinoma.
  
  
  METHODS
  In a retrospective study, we identified 39 patients (24 females, 15 men; average age 47 years [range 12-78 years]) with insulinoma. Sixteen patients were diagnosed by spontaneous hypoglycaemia. Twenty-three patients with insulinoma were tested with a 48-hour fasting test and compared to 31 healthy controls who had a negative fasting test and were followed up for at least two years.
  
  
  RESULTS
  The fast was terminated due to neuroglycopenic symptoms in 4 patients (17.4%) at the 12th hour, in 17 patients (73.9%) at the 24th hour, and in 22 patients (95.7%) at the 48th hour. One patient with insulinoma had no neuroglycopenic symptoms, but was diagnosed by glucose and insulin levels during the 48-hour fast. Healthy controls had significantly higher blood glucose and lower insulin levels, and a lower insulin-glucose ratio than patients with insulinoma at the end of the fast.
  
  
  CONCLUSIONS
  In conclusion, the 48-hour fasting test was successful in the diagnosis of insulinoma in 95.7% of patients. In this series we did not observe a need for fasting beyond 48 hours.
authors.affiliation: Clinical Endocrinology, Internal Medicine Center for Gastroenterology, Hepatology, and Endocrinology, Charité Campus Mitte, Charité Universitätsmedizin Berlin, Berlin, Germany. marcus.quinkler@charite.de
authors.forename: M
authors.initials: M
authors.lastname: Quinkler
authors.forename: F
authors.initials: F
authors.lastname: Strelow
authors.forename: M
authors.initials: M
authors.lastname: Pirlich
authors.forename: W
authors.initials: W
authors.lastname: Rohde
authors.forename: H
authors.initials: H
authors.lastname: Biering
authors.forename: H
authors.initials: H
authors.lastname: Lochs
authors.forename: H
authors.initials: H
authors.lastname: Gerl
authors.forename: C J
authors.initials: CJ
authors.lastname: Strasburger
authors.forename: M
authors.initials: M
authors.lastname: Ventz
mesh_terms: D000293:Adolescent; D000328:Adult; D001786:Blood Glucose; D002648:Child; D003710:Demography; D005215:Fasting / Q000502:physiology*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D007340:Insulinoma / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D001786:Blood Glucose; D007328:Insulin