Insulinoma (patient information)

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Editor-in-Chief: C. Michael Gibson, M.S.,M.D. [mailto:mgibson@perfuse.org] Phone:617-632-7753; Associate Editor-In-Chief: Jinhui Wu, M.D.

Overview
An insulinoma is a tumor in the pancreas that produces too much insulin.

What are the symptoms of Insulinoma?

 * Anxiety
 * Behavior changes
 * Clouded vision
 * Confusion
 * Convulsions
 * Dizziness
 * Headache
 * Hunger
 * Loss of consciousness
 * Rapid heart rate
 * Sweating
 * Tremor
 * Weight gain

What causes Insulinoma?
The pancreas is an organ in the abdomen that makes several enzymes and hormones, including the hormone insulin. Insulin's job is to reduce the level of sugar (glucose) in the blood by helping it move into cells.

Most of the time when your blood sugar level drops too low, the pancreas stops making insulin until your blood sugar returns to normal. Tumors of the pancreas that produce too much insulin are called insulinomas. Insulinomas keep making insulin, even when your blood sugar drops too low.

High blood 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.

These tumors are very rare in children. Most children with high blood insulin levels have many areas of overactive insulin-releasing cells in the pancreas, instead of a single tumor.

Taking medications that cause too much insulin in the blood, either accidentally or on purpose, is about as common as insulinoma.

More than 90% of insulinomas are non-cancerous (benign) tumors. People with the genetic syndrome called multiple endocrine neoplasia type I are at risk for insulinomas and other endocrine tumors.

Diagnosis
After fasting, your blood may be tested for:


 * Blood C-peptide level
 * Blood glucose level
 * Blood insulin level
 * Drugs that cause the pancreas to release insulin

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:


 * Endoscopic ultrasound
 * Octreotide scan
 * Pancreatic arteriography
 * Pancreatic venous sampling for insulin

When to seek urgent medical care?
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.

Treatment options
Surgery is the recommended treatment for insulinoma. The tumor is first found by tests or surgery. Medication may be used to get patients stable before 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 if 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.

Where to find medical care for Insulinoma?
Directions to Hospitals Treating insulinoma

Prevention of Insulinoma
For the cause is not clear, there is no known method for prevention.

What to expect (Outlook/Prognosis)?
As a kind of benign tumor, the prognosis of insulinoma is good. Surgery can cure most patients. But a severe hypoglycemic reaction may be life-threatening for some patients.

Possible complications

 * Severe hypoglycemic reaction
 * Spreading of a cancerous tumor (metastasis)