Insulinoma

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Insulinoma is the beta cells tumor of the pancreas characterized by the signs and symptoms of hypoglycemia due to increased secretion of insulin.

What is the pathophysiology of Insulinoma?

Insulinoma is derived mainly from pancreatic islet cells , that secrets insulin. In insulinoma excessive amount of insulin is produced in short burst ,causing low blood glucose level.

What causes the Insulinoma?

The exact cause of this disease is still unknown but believed that MEN1 gene located at 11q13 is involved in the pathogenesis of this tumor.

What is the signs and symptoms of Insulinoma?

The signs and symptoms are similar to other hypoglycemia is general which includes:

1. Hypoglycemia occurs several hour after food.
2. Diplopia, blurred vision
3. Confusion ,abnormal behavior
4. Amnesia
5. Seizure
6. Weakness, sweating, tachycardia, hunger, tachycardia (these symptoms are results due to hypoglycemia cause adrenalin release).
7. Symptoms can be aggravated by alcohol, exercise and used of sulfonylureas.
8. Weight gain
9. Symptoms is reversal after glucose administration.

How is Insulinoma diagnosed?

Diagnosis relies on clinical finding, laboratory examination and radiological examination.

Laboratory examination includes:

A) Fasting (up to 72h) blood levels show:

1. Insulin level 10U/mL or more
2. Blood glucose less than 40mg/dL
3. C-peptide more than 205ng/mL
4. Proinsulin greater than 25%
5. Ratios of insulin to plasma glucose is increase

B) Whipple triad is positive ,which consists of :

1. Symptoms of hypoglycemia
2. Low blood glucose( 40-50mg/dL)
3. Relief of symptoms after intravenous administration of glucose.

C)Radiographic imaging including:

1. Computed tomography(CT) scan : Only 20% patients shows mass in CT scan because 80% have mass size less then 2cm. CT scan have the sensitivity of 82-94%.
2. Endoscopic ultrasound detects 77% of insulinoma .

Low blood sugar with a high insulin and c-peptide level confirm the diagnosis.

How is Insulinoma Managed ?

1. Surgery is the gold standard treatment for insulinoma . 90% of insulinoma is cured by surgery. Only tumor is removed if there is a single tumor. However ,if there is multiple tumor partial pancreatectomy(part of the pancreas removed) is needed.
2. Medical management with Diazoxide and somatostatin(octreotide) is reserved for patients who are unable or unwilling to undergo surgical treatment or unresectable metastatic disease .
3. CT-guided radiofrequency ablation has been used in an elderly patients.

What is the prognosis of Insulinoma?

After surgery prognosis is excellent.

References:

1. Sabiston textbook of surgery 18th edition
2. The Washington manual of surgery, 5th edition.
3. emedicine.medscape.com
4. http://www.medicinenet.com
5. http://www.sciencedirect.com
6. http://en.wikipedia.org

Filed Under: General • Surgery

Tags: cancer in the pancreas, caner of the pancreas, featured, Insulinoma, insulinoma symptoms, of pancreatic cancer, what is the treatment of insulinoma