The diagnosis of<unk>  is suspected in a patient with symptomatic fasting hypoglycemia. The conditions of Whipple’s triad need to be met for the diagnosis of "true hypoglycemia" to be made: # symptoms and signs of hypoglycemia, # concomitant plasma glucose level of 45 mg/dL (2.5 mmol/L) or less, and # reversibility of symptoms with administration of glucose. Blood tests These blood tests are needed to diagnose<unk> : * glucose * insulin * C-peptide If available, a proinsulin level might be useful, as well. Other blood tests may help rule out other conditions which can cause hypoglycemia. 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 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 then stopped at that point, and the hypoglycemia is treated with intravenous dextrose or carbohydrate-containing food or drink. Diagnostic imaging The<unk>  might be localized by noninvasive means, using ultrasound, CT scan, or MRI techniques. An indium-111 pentetreotide scan is more sensitive than ultrasound, CT, or MRI for detection of somatostatin receptor positive tumors, but not a good diagnostic tool for<unk> s. An endoscopic ultrasound has a sensitivity of 40-93% (depending on the location of the tumor) for detecting<unk> s. Sometimes, angiography with percutaneous transhepatic pancreatic vein catheterization to sample the blood for insulin levels is required. Calcium can be injected into selected arteries to stimulate insulin release from various parts of the pancreas, which can be measured by sampling blood from their respective veins. The use of calcium stimulation improves the specificity of this test. During surgery to remove an<unk> , an intraoperative ultrasound can sometimes localize the tumor, which helps guide the surgeon in the operation and has a higher sensitivity than noninvasive imaging tests.
Insulinoma
Reactive hypoglycemia
Glucagonoma
Metastatic insulinoma
Somatostatinoma
Congenital hyperinsulinism
Idiopathic hypoglycemia
Adie syndrome