Insulinoma
Insulinoma | |
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Pathology of pancreatic endocrine tumour (insulinoma). | |
Specialty | Oncology |
An insulinoma is a
Beta cells secrete insulin in response to increases in
As a result, patients present symptoms of low blood glucose (hypoglycemia), which are improved by eating. The diagnosis of an insulinoma is usually made biochemically with low blood glucose, elevated insulin, proinsulin, and C-peptide levels, and confirmed by localizing the tumour with medical imaging or angiography. The definitive treatment is surgery.[3]
Signs and symptoms
Patients with insulinomas usually develop
Diagnosis
The diagnosis of insulinoma is suspected in a patient with symptomatic fasting hypoglycemia. The conditions of
- 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 insulinoma:[6]
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 tumour.[citation needed]
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.[citation needed]
Diagnostic imaging
The insulinoma might be localized by noninvasive means, using
Sometimes,
Treatment
The definitive management is the surgical removal of the insulinoma. This may involve removing part of the pancreas, as well (
Prognosis
Most patients with benign insulinomas can be cured with surgery. Persistent or recurrent hypoglycemia after surgery tends to occur in patients with multiple tumours. About 2% of patients develop
Incidence
Insulinomas are rare
History
Hypoglycemia was first recognized in the 19th century. In the 1920s, after the discovery of insulin and its use in the treatment of diabetics, hyperinsulinism was suspected to be a cause of hypoglycemia in nondiabetics. A pioneering description of hyperinsulinism as a cause of hypoglycemia was published by Seale Harris in 1924. The first report of a surgical cure of hypoglycemia by removing an islet cell tumour was in 1929.[citation needed]
An insulinoma removed from a woman in Munich provided insulin mRNA that was used in the first human gene cloning experiment. In 1979, Axel Ulrich cloned this gene into E. coli. Most therapeutic insulin used today derives from this woman's tumour.[8]
Additional images
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Pancreatic insulinoma
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Pancreatic insulinoma
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Chromogranin A
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Insulin immunostain
See also
- Causes of hypoglycemia
- Metastatic Insulinoma
References
- S2CID 7329783.
- ^ MeSH website, tree at: "Pancreatic Neoplasms [C04.588.322.475]",[dead link] accessed 16 October 2014
- ^ a b "Insulinomas". The Lecturio Medical Concept Library. Retrieved 27 July 2021.
- ISBN 978-0-323-29738-7.
- PMID 24641805.
- ^ "Insulinomas". The Lecturio Medical Concept Library. Retrieved 22 July 2021.
- S2CID 5634475.
- ^ "Genentech and Axel Ulrich clone the human insulin gene". Tacomed.com. Archived from the original on 27 September 2017. Retrieved 13 June 2017.
Further reading
- Larsen PR, Williams RL (2003). Williams textbook of endocrinology (10th ed.). Philadelphia: WB Saunders. ISBN 978-0-7216-9184-8.
- Doppman, John L. (15 August 1995). "Localization of Insulinomas to Regions of the Pancreas by Intra-arterial Stimulation with Calcium". Annals of Internal Medicine. 123 (4): 269–273. S2CID 20993342.
- Vella, Adrian. "Insulinoma". UpToDate.