An insulinoma is a rare type of tumor that originates in the pancreas. This tumor causes the body to produce too much insulin, a hormone that regulates blood sugar levels. The overproduction of insulin leads to hypoglycemia, a condition characterized by abnormally low blood sugar.
What is an Insulinoma
An insulinoma is a neuroendocrine tumor that develops from the pancreas’s beta cells. These cells produce and release insulin. Most insulinomas are benign, meaning they are non-cancerous and do not spread. However, a small percentage can be malignant and spread to other body parts, such as lymph nodes or the liver.
The tumor causes unregulated insulin secretion, meaning it releases insulin continuously regardless of the body’s actual need. This leads to blood glucose levels dropping significantly.
Symptoms of Insulinoma
Symptoms of an insulinoma primarily arise from hypoglycemia, or low blood sugar. These can be categorized based on how the body reacts to insufficient glucose. Neuroglycopenic symptoms occur when the brain lacks glucose, leading to confusion, difficulty concentrating, blurred vision, headaches, and behavioral changes. Severe instances may include seizures or coma.
Adrenergic symptoms are the body’s response to sudden blood sugar drops, triggering adrenaline release. These include sweating, rapid heartbeat, tremors, anxiety, and intense hunger. Symptoms often appear during fasting, like in the morning, or after prolonged physical activity, and improve quickly with sugar consumption.
Diagnosing Insulinoma
Diagnosis begins with evaluating symptoms suggesting low blood sugar. Healthcare providers look for Whipple’s triad: symptoms of low blood sugar, a documented low blood sugar level, and symptom improvement after consuming sugar. A crucial step is a supervised 72-hour fast, usually in a hospital. During this fast, blood samples measure glucose, insulin, C-peptide, and proinsulin levels. An inappropriately high insulin level with low blood glucose strongly indicates an insulinoma.
Once biochemical evidence suggests an insulinoma, imaging studies locate the tumor within the pancreas. Common techniques include computed tomography (CT), magnetic resonance imaging (MRI), and endoscopic ultrasound (EUS). EUS, using an ultrasound probe in the digestive tract, is effective for small tumors. Specialized tests like PET scans or selective arterial calcium stimulation tests may also pinpoint the tumor’s location.
Treatment Options
Surgical removal of the tumor is the primary treatment. The specific procedure depends on the tumor’s size and location. For smaller tumors, enucleation removes the tumor while preserving surrounding pancreatic tissue. Larger tumors or those in specific pancreatic parts may require a partial pancreatectomy, removing a portion of the pancreas. In rare, complex cases, a Whipple procedure, removing the head of the pancreas and parts of the small intestine, may be considered.
For individuals unsuitable for surgery or with spread malignant tumors, medical management controls symptoms. Medications like diazoxide reduce insulin secretion. Somatostatin analogs, such as octreotide or lanreotide, also suppress insulin release from the tumor. For metastatic insulinoma, chemotherapy or targeted treatments may manage tumor growth and reduce symptoms.
Prognosis and Follow-Up
The outlook for individuals with insulinoma is favorable, especially when the benign tumor is completely removed surgically. Most benign insulinomas are cured with surgery, leading to a high success rate and good long-term survival for non-metastatic cases.
The prognosis for malignant insulinomas is more varied, as these tumors can spread. Even after successful treatment, ongoing medical observation and follow-up care are important to monitor for recurrence or manage persistent symptoms. Regular check-ups ensure stable blood sugar levels and prompt addressing of new developments.