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Alternative Names Return to topInsuloma; Islet cell adenoma
Definition Return to top
An insulinoma is a tumor in the pancreas that produces too much insulin.
Causes Return to top
The pancreas is an organ in the abdomen that makes several enzymes and hormones, including the hormone insulin. Insulin is needed to control blood sugar levels. Tumors of the pancreas that produce too much insulin are called insulinomas.
High insulin levels cause low blood sugar levels (hypoglycemia). Hypoglycemia may be mild, leading to symptoms such as anxiety and hunger. Or it can be severe, leading to seizures, coma, and even death.
Insulinomas are rare tumors. They usually occur as single, small tumors in adults.
They are very rare in children. Most children with hyperinsulinemia have many areas of overactive insulin-releasing cells in the pancreas, instead of a single tumor.
Accidentally or purposefully taking medications that cause too much insulin production is about as common as insulinoma.
Most insulinomas are non-cancerous (benign) tumors. Only 5 - 10% are cancerous. People with the genetic syndrome called multiple endocrine neoplasia type I are at risk for insulinomas and other endocrine tumors.
Symptoms Return to top
Exams and Tests Return to top
After fasting, your blood may be tested for:
CT or MRI scan of the abdomen may be done to look for a tumor in the pancreas. If the test is negative, one of the following tests may be performed:
Treatment Return to top
Surgery is the typical treatment for insulinoma. The location of the tumor is first found by tests or surgery.
If there is a single tumor it will be removed. However, if there are many tumors, part of the pancreas will need to be removed (partial pancreatectomy). At least 15% of the pancreas must be left to produce its enzymes. This may prevent the surgeon from removing the whole insulinoma tumor.
If no tumor is found during surgery, or you are not a candidate for surgery, you may get the drug diazoxide to lower insulin production and avoid hypoglycemia. A diuretic (water pill) is given with this medication to prevent the body from retaining fluid.
Octreotide is used to reduce insulin release in some patients. Medication is also used to get patients stable before surgery.
Outlook (Prognosis) Return to top
In most cases, the tumor is non-cancerous (benign), and surgery can treat the disease. However, a severe hypoglycemic reaction or the spread of a cancerous tumor to other organs can be life-threatening.
Possible Complications Return to top
When to Contact a Medical Professional Return to top
Call your health care provider if you develop any symptoms of insulinoma. Convulsions and decreased consciousness are an emergency -- call 911 or your local emergency number.
References Return to top
Cryer PE. Glucose homeostasis and hypoglycemia. In: Kronenberg HM, Shlomo M, Polonsky KS, Larsen PR, eds. Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier;2008:chap 33.Update Date: 8/9/2008 Updated by: David C. Dugdale III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Deborah Wexler, MD, Assistant Professor of Medicine, Harvard Medical School, Endocrinologist, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.