Insulinoma laboratory tests

Insulinoma Microchapters
Home
Patient Information
Overview
Historical Perspective
Classification
Pathophysiology
Causes
Differentiating Insulinoma from other Diseases
Epidemiology and Demographics
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
Staging
Diagnostic Criteria
History and Symptoms
Physical Examination
Laboratory Findings
X-ray
Ultrasound
CT
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Surgery
Primary Prevention
Secondary Prevention
Cost-Effectiveness of Therapy
Future or Investigational Therapies
Case Studies
Case #1
Insulinoma laboratory tests On the Web
Most recent articles
Most cited articles
Review articles
CME Programs
Powerpoint slides
Images
American Roentgen Ray Society Images of Insulinoma laboratory tests All Images X-rays Echo & Ultrasound CT Images MRI
Ongoing Trials at Clinical Trials.gov
US National Guidelines Clearinghouse
NICE Guidance
FDA on Insulinoma laboratory tests
CDC on Insulinoma laboratory tests
Insulinoma laboratory tests in the news
Blogs on Insulinoma laboratory tests
Directions to Hospitals Treating Insulinoma
Risk calculators and risk factors for Insulinoma laboratory tests

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Parminder Dhingra, M.D. [2]

Overview

Laboratory findings consistent with the diagnosis of insulinoma include 72 hour suppression test and Whipple's triad.

Laboratory Tests

Laboratory findings consistent with the diagnosis of insulinoma include:

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. Hypoglycemia (plasma glucose < 50 mg/dL)

2. Neuroglycopenic symptoms

3. Reversibility of symptoms with administration of glucose

Suppression Tests

The gold standard blood tests needed to diagnose insulinoma during a 72 hour fast are:

• Plasma glucose level
• Insulin
• C-peptide
• Pro-insulin

The sensitivity of combination of these 4 tests after 72h fasting is around 99%.

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 tumor. 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.