Insulinoma laboratory tests: Difference between revisions
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*[[C-peptide]] | *[[C-peptide]] | ||
*Pro-insulin | *Pro-insulin | ||
The sensitivity of combination of these 4 tests after 72h fasting is around 99%. | |||
===Suppression tests=== | ===Suppression tests=== | ||
Revision as of 15:09, 5 October 2015
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Parminder Dhingra, M.D. [2]
Overview
Laboratory Tests
Laboratory findings consistent with the diagnosis of insulinoma include:[1]
Whipple's Traid
The diagnosis of insulinoma is suspected in a patient with symptomatic fasting hypoglycemia. The conditions of Whipple’s triad need to be met for the diagnosis of insulinoma are:[1]
- 1. Hypoglycemia(plasma glucose < 50 mg/dL)
- 2. Neuroglycopenic symptoms
- 3. Reversibility of symptoms with administration of glucose
Blood tests
The gold standard blood tests needed to diagnose insulinoma during a 72 hour fast are:[1]
The sensitivity of combination of these 4 tests after 72h fasting is around 99%.
Suppression tests
Normally, endogenous insulin production is suppressed in the setting of hypoglycemia. A 72-hour fast, usually supervised in a hospital setting, can be done to see if insulin levels fail to suppress, which is a strong indicator of the presence of an insulin-secreting tumour.
- During the test, the patient may have calorie-free and caffeine-free liquids. Capillary blood glucose is measured every 4 hours using a reflectance meter, until values < 60 mg/dL (3.3 mmol/L) are obtained. Then, the frequency of blood glucose measurement is increased to every hour until values are < 49 mg/dL (2.7 mmol/L). At that point, or when the patient has symptoms of hypoglycemia, a blood test is drawn for serum glucose, insulin, proinsulin, and C-peptide levels. The fast is stopped at that point, and the hypoglycemia treated with intravenous dextrose or calorie-containing food or drink.
References
- ↑ 1.0 1.1 1.2 Okabayashi T, Shima Y, Sumiyoshi T, Kozuki A, Ito S, Ogawa Y; et al. (2013). "Diagnosis and management of insulinoma". World J Gastroenterol. 19 (6): 829–37. doi:10.3748/wjg.v19.i6.829. PMC 3574879. PMID 23430217.