An insulinoma is a tumor in the pancreas that produces too much insulin.
The pancreas is an organ in the abdomen. The pancreas 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 sugar move into cells.
Enzymes are complex proteins that cause a specific chemical change in all parts of the body. For example, they can help break down the foods we eat ...Read Article Now Book Mark Article
Most of the time when your blood sugar level decreases, the pancreas stops making insulin to make sure that your blood sugar stays in the normal range. Tumors of the pancreas that produce too much insulin are called insulinomas. Insulinomas keep making insulin, and can make your blood sugar level too low (hypoglycemia).
A high blood insulin level causes a low blood sugar level (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.
Low blood sugar is a condition that occurs when the body's blood sugar (glucose) decreases and is too low. Blood sugar below 70 mg/dL (3. 9 mmol/L) i...Read Article Now Book Mark Article
Insulinomas are very rare tumors. They usually occur as single, small tumors. But there can also be several small tumors.
Most insulinomas are non-cancerous (benign) tumors. People with certain genetic disorders, such as multiple endocrine neoplasia type I, are at higher risk for insulinomas.
Symptoms are most common when you are fasting or skip or delay a meal. Symptoms may include:
- Anxiety, behavior changes, or confusion
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- Clouded vision
- Loss of consciousness or coma
- Convulsions or tremor
- Dizziness or headache
- Hunger between meals; weight gain is common
- Fast heart rate or palpitations
Exams and Tests
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
- The response of your body to a shot of glucagon
An abdominal CT scan is an imaging method. This test uses x-rays to create cross-sectional pictures of the belly area. CT stands for computed tomog...Read Article Now Book Mark Article
An abdominal magnetic resonance imaging scan is an imaging test that uses powerful magnets and radio waves. The waves create pictures of the inside ...Read Article Now Book Mark Article
A positron emission tomography scan is a type of imaging test. It uses a radioactive substance called a tracer to look for disease in the body. A po...Read Article Now Book Mark Article
- Endoscopic ultrasound (test that uses a flexible scope and sound waves to view digestive organs)
- Octreotide scan (special test that checks for specific hormone-producing cells in the body)
- Pancreatic arteriography (test that uses special dye to view the arteries in the pancreas)
- Pancreatic venous sampling for insulin (test that helps locate the approximate location of the tumor inside the pancreas)
Surgery is the usual treatment for insulinoma. If there is a single tumor, it will be removed. If there are many tumors, part of the pancreas will need to be removed. At least 15% of the pancreas must be left to produce normal levels of enzymes for digestion.
In rare cases, the entire pancreas is removed if there are many insulinomas or they continue to come back. Removing the entire pancreas leads to diabetes because there is no longer any insulin being produced. Insulin shots (injections) are then required.
If no tumor is found during surgery, or if you can't have surgery, you may get the medicine diazoxide to lower insulin production and prevent hypoglycemia. A water pill (diuretic) is given with this medicine to prevent the body from retaining fluid. Octreotide is another medicine that is used to reduce insulin release in some people.
In most cases, the tumor is non-cancerous (benign), and surgery can cure the disease. But a severe hypoglycemic reaction or the spread of a cancerous tumor to other organs can be life-threatening.
Complications may include:
- Severe hypoglycemic reaction
- Spread of a cancerous tumor (metastasis)
- Diabetes if the entire pancreas is removed (rare), or food not being absorbed if too much of the pancreas is removed
- Inflammation and swelling of the pancreas
When to Contact a Medical Professional
Call your health care provider if you develop any symptoms of insulinoma. Seizures and losing consciousness are an emergency. Call 911 or the local emergency number right away.
Brent Wisse, MD, board certified in Metabolism/Endocrinology, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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National Comprehensive Cancer Network website. NCCN clinical practice guidelines in oncology (NCCN guidelines): Neuroendocrine and adrenal tumors. Version 2.2020. www.nccn.org/professionals/physician_gls/pdf/neuroendocrine.pdf. Updated July 24, 2020. Accessed November 11, 2020.
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