This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hirshberg, B. Articles by Gorden, P. Search for Related Content PubMed PubMed Citation Articles by Hirshberg, B. Articles by Gorden, P.

Forty-Eight-Hour Fast: The Diagnostic Test for Insulinoma

Division of Intramural Research, National Institute of Diabetes, Digestive and Kidney Diseases (B.H., A.L., M.C.S.); Surgical Metabolism Section, National Cancer Institute (D.L.B., S.K.L., H.R.A.); and Department of Diagnostic Radiology (J.L.D.), National Institutes of Health, Bethesda, Maryland 20892

Address all correspondence and requests for reprints to: Dr. Boaz Hirshberg, Division of Intramural Research, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Building 10, Room 85-235B, Bethesda, Maryland 20892.

Insulinoma causes fasting hypoglycemia due to inappropriate insulin secretion. Its diagnosis is based on demonstrating Whipple’s triad during a supervised 72-h fast. For 75 yr, the 72-h fast has been the cornerstone for the diagnosis; however, it has never been critically assessed using newer assays for insulin, C peptide, and proinsulin. Thus, the aim of the current study is to assess the need for a full 72-h fast for the diagnosis of insulinoma. Patients with suspected hypoglycemia with documented glucose concentrations below 45 mg/dL were admitted to the NIH. Data obtained during the supervised fast of patients with pathologically proven insulinoma over a 30-yr period (1970–2000) were reviewed. We identified 127 patients with insulinoma. The average age of patients was 42.7 ± 15.9 yr, with a predominance of females (62%). 107 patients had a benign tumor, 20 had malignant insulinoma, and 15 patients had multiple endocrine neoplasia type 1. The fast was terminated due to hypoglycemia in 44 patients (42.5%) by 12 h, 85 patients (66.9%) by 24 h, and 120 (94.5%) by 48 h. Seven patients fasted beyond 48 h despite subtle neuroglycopenic symptoms and glucose and insulin concentrations diagnostic of insulinoma. Immunoreactive proinsulin was elevated at the beginning of the fast in 90% of 42 patients. Proinsulin in noninsulinoma, in contrast to insulinoma, patients is usually suppressible; therefore, samples taken in the suppressed state have the greatest diagnostic value. We conclude that with the current available insulin and proinsulin assays, the diagnosis of insulinoma can be made within 48 h. Thus, the 48-h fast should replace the 72-h fast in textbooks and hospital protocols as the new diagnostic standard.

This article has been cited by other articles:

				M. B. Lodish, A. C. Powell, M. Abu-Asab, C. Cochran, P. Lenz, S. K. Libutti, J. F. Pingpank, M. Tsokos, and P. Gorden Insulinoma and Gastrinoma Syndromes from a Single Intrapancreatic Neuroendocrine Tumor J. Clin. Endocrinol. Metab., April 1, 2008; 93(4): 1123 - 1128. [Abstract] [Full Text] [PDF]

				P H Kann, D Ivan, A Pfutzner, T. Forst, P Langer, and S Schaefer Preoperative diagnosis of insulinoma: low body mass index, young age, and female gender are associated with negative imaging by endoscopic ultrasound Eur. J. Endocrinol., August 1, 2007; 157(2): 209 - 213. [Abstract] [Full Text] [PDF]

				D Vezzosi, A Bennet, J Fauvel, and P Caron Insulin, C-peptide and proinsulin for the biochemical diagnosis of hypoglycaemia related to endogenous hyperinsulinism Eur. J. Endocrinol., July 1, 2007; 157(1): 75 - 83. [Abstract] [Full Text] [PDF]

				P. Kar, P. Price, S. Sawers, S. Bhattacharya, R. H. Reznek, and A. B. Grossman Insulinomas May Present with Normoglycemia after Prolonged Fasting but Glucose-Stimulated Hypoglycemia J. Clin. Endocrinol. Metab., December 1, 2006; 91(12): 4733 - 4736. [Abstract] [Full Text] [PDF]

				F. J. Service and P. C. O'Brien Increasing Serum Betahydroxybutyrate Concentrations during the 72-Hour Fast: Evidence against Hyperinsulinemic Hypoglycemia J. Clin. Endocrinol. Metab., August 1, 2005; 90(8): 4555 - 4558. [Abstract] [Full Text] [PDF]

				G. A. Kaltsas, G. M. Besser, and A. B. Grossman The Diagnosis and Medical Management of Advanced Neuroendocrine Tumors Endocr. Rev., June 1, 2004; 25(3): 458 - 511. [Abstract] [Full Text] [PDF]

				R Gama, J D Teale, and V Marks Best Practice No 173: Clinical and laboratory investigation of adult spontaneous hypoglycaemia J. Clin. Pathol., September 1, 2003; 56(9): 641 - 646. [Abstract] [Full Text] [PDF]

				C. W. Chia and C. D. Saudek The Diagnosis of Fasting Hypoglycemia Due to an Islet-Cell Tumor Obscured by a Highly Specific Insulin Assay J. Clin. Endocrinol. Metab., April 1, 2003; 88(4): 1464 - 1467. [Abstract] [Full Text] [PDF]

				M. Sumarac-Dumanovic, D. Micic, and V. Popovic Noninsulinoma Pancreatogenous Hypoglycemia in Adults: Presentations of Two Cases J. Clin. Endocrinol. Metab., May 1, 2001; 86(5): 2328b - 2329. [Full Text]

				S. Vig, M. Lewis, K. J. Foster, and A. Stacey-Clear Lessons to be learned: a case study approach Insulinoma presenting as a change in personality The Journal of the Royal Society for the Promotion of Health, March 1, 2001; 121(1): 56 - 61. [Abstract] [PDF]