Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] ; Associate Editor(s)-in-Chief: Amandeep Singh M.D. [2]
The diagnosis of insulinoma is based on the Whipple's triad , which includes blood glucose < 55 mg/dL, symptoms of hypoglycemia that can be neuroglycopenic (visual disturbances , confusion , weakness , seizures , coma ) or adrenergic symptoms (sweating , tremors , palpitations , and hyperphagia ) and resolution of symptoms after ingestion/infusion of glucose . It is also diagnosed on the basis of radioimmunoassay (RIA ) and Immunochemiluminescent assay (ICMA) in the absence of hypoglycemia causing agents e.g. insulin and oral hypoglycemic agents (e.g. sulfonylureas ) by insulin level (>6 μU/mL (43 pmol/L by RIA and ≥ 3 μU/mL by ICMA, glucose level of < 2.5mmol/L (55mg/dL) and C-peptide level of ≥ 200 pmol/L and/or proinsulin level ≥ 25% or ≥ 22pmol/L. The gold standard for the diagnosis of insulinoma is 72-hour fasting test.
Hypoglycemia (fasting blood glucose < 55 mg/dL)
Symptoms of hypoglycemia
Improvement of symptoms after glucose infusion
The diagnosis of insulinoma is based on the biochemical assay with radioimmunoassay (RIA) and immunochemiluminescent assay (ICMA) in the absence of plasma sulfonylureas (or drug causing hypoglycemia ) as below: [ 5] [ 6]
Insulin level > 6 μU/mL (43 pmol/L by RIA and ≥3 μU/ml by ICMA
Glucose level < 2.5mmol/L (55 mg/dL)
C-peptide level ≥ 200 pmol/L
Proinsulin level ≥25% or ≥22pmol/L is also included in some criteria
The gold standard for diagnosis classically had been 72-hour fasting test.[ 6] [ 5]
33% patients develop symptoms in 12 hours, 80% at 24 hours, 90% after 48 hours and 100% after 72 hours of fasting.
Algorithm used commonly[ 7]
Suspicion of Insulinoma
Whipple's triad confirmed
72 hour fast
Positive
Negative
MRI /CT
Prolonged OGTT or mixed meal
No visible lesion
Visible lesion(s)
Unresectableliver metastasis
Nohypoglycemia
Hypoglycemia
No follow up
Differential diagnosis of postprandial hypoglycemia
EUS
Treat metastatic disease
No visible lesion(s)
Visible lesion(s)
GLP-1 Scan or ASVS
No lesion(s)
Identified lesion(s)
Medical control and reevaluation
Surgical exploration (intraoperative US)
Single lesion(s)
Multiple lesion(s)
Excision
ASVS
Excision based on ASVS
Abbreviations: EUS: Endoscopic ultrasound, ASVS: Arterial stimulation venous sampling, GLP-1: Glucagon-like-peptide 1, OGTT: Oral glucose tolerance test
↑ Whipple AO, Frantz VK (1935). "ADENOMA OF ISLET CELLS WITH HYPERINSULINISM: A REVIEW" . Ann. Surg . 101 (6): 1299–335. PMC 1390871 . PMID 17856569 .
↑ Cryer PE, Axelrod L, Grossman AB, Heller SR, Montori VM, Seaquist ER; et al. (2009). "Evaluation and management of adult hypoglycemic disorders: an Endocrine Society Clinical Practice Guideline" . J Clin Endocrinol Metab . 94 (3): 709–28. doi :10.1210/jc.2008-1410 . PMID 19088155 .
↑ Metz DC, Jensen RT (2008). "Gastrointestinal neuroendocrine tumors: pancreatic endocrine tumors" . Gastroenterology . 135 (5): 1469–92. doi :10.1053/j.gastro.2008.05.047 . PMC 2612755 . PMID 18703061 .
↑ Boukhman MP, Karam JH, Shaver J, Siperstein AE, Duh QY, Clark OH (1998). "Insulinoma--experience from 1950 to 1995" . West J Med . 169 (2): 98–104. PMC 1305178 . PMID 9735690 .
↑ 5.0 5.1 Metz, David C.; Jensen, Robert T. (2008). "Gastrointestinal Neuroendocrine Tumors: Pancreatic Endocrine Tumors". Gastroenterology . 135 (5): 1469–1492. doi :10.1053/j.gastro.2008.05.047 . ISSN 0016-5085 .
↑ 6.0 6.1 Grant CS (2005). "Insulinoma" . Best Pract Res Clin Gastroenterol . 19 (5): 783–98. doi :10.1016/j.bpg.2005.05.008 . PMID 16253900 .
↑ Falconi M, Eriksson B, Kaltsas G, Bartsch DK, Capdevila J, Caplin M, Kos-Kudla B, Kwekkeboom D, Rindi G, Klöppel G, Reed N, Kianmanesh R, Jensen RT (2016). "ENETS Consensus Guidelines Update for the Management of Patients with Functional Pancreatic Neuroendocrine Tumors and Non-Functional Pancreatic Neuroendocrine Tumors" . Neuroendocrinology . 103 (2): 153–71. doi :10.1159/000443171 . PMC 4849884 . PMID 26742109 .
Template:WH
Template:WS