An insulinoma is a rare type of neuroendocrine tumor of the pancreas that secretes insulin, a hormone that lowers the levels of sugar (glucose) in the blood.
These tumors arise from cells in the pancreas that produce insulin.
Symptoms caused by low blood sugar (hypoglycemia) include faintness, weakness, headache, and confusion.
Diagnosis includes blood and imaging tests.
Treatment is surgery when possible and sometimes chemotherapy.
Insulinomas are a type of pancreatic neuroendocrine tumor. The average age at diagnosis is 50. Only 10% of insulinomas are cancerous.
Symptoms of Insulinoma
Symptoms of an insulinoma result from low levels of sugar (glucose) in the blood (hypoglycemia), which occur when the person does not eat for several hours (most often in the morning after an all-night fast). The symptoms include faintness, weakness, trembling, awareness of the heartbeat (palpitations), sweating, nervousness, and profound hunger.
Other symptoms include headache, confusion, vision abnormalities, unsteadiness, and marked changes in behavior or thinking.
The low levels of sugar in the blood may even lead to a loss of consciousness, seizures, and coma.
Diagnosis of Insulinoma
Blood tests
Imaging tests
Diagnosing an insulinoma can be difficult. Doctors try to do blood tests while the person has symptoms and has not eaten. Blood tests include measurements of blood glucose levels and insulin levels. Very low levels of glucose and high levels of insulin in the blood indicate the presence of an insulinoma. Because many people have symptoms only occasionally, doctors may admit them to the hospital. In the hospital, the person fasts for at least 48 hours, sometimes up to 72 hours, and is closely monitored. During that time, the symptoms usually appear, and blood tests are done to measure the levels of glucose and insulin.
If the blood tests suggest the person has an insulinoma, the location must then be pinpointed. Imaging tests, such as computed tomography (CT) and endoscopic ultrasound (in which a viewing tube with an ultrasound probe on the tip is passed into the upper part of the small intestine) or positron emission tomography (PET), can be used to locate the tumor. Sometimes exploratory surgery is needed.
Treatment of Insulinoma
Surgical removal
Diazoxide or sometimes octreotide or lanreotide
Sometimes chemotherapy
The primary treatment for an insulinoma is surgical removal, which has a cure rate of about 90%.
Chemotherapy may help to control the tumor.
