What Is Insulinoma?
August 8, 2009
Insulinoma (also known as Beta cell tumour) majorly occurs in the tail and body of the pancreas. It may be benign or malignant tumour of pancreatic beta cells.
Most of them are benign (80%), some are malignant (10%) and some are multiple (10%). These insulinomas produce excess of insulin, which is responsible for the clinical features.
Clinical Features
The clinical features are related to cerebral glucose deprivation (palpitation, weakness, sweating, memory loss, coma) and also related to gastrointestinal tract (hunger abdominal pain, diarrhoea). The pain may mimic the pain of duodenal ulcer.
Diagnostic clinical feature is Whipple’s triad, which comprises hypoglycemia in the morning hours or during fasting state, fasting blood glucose levels less than 50 mg/dL during the attack and relief of symptoms following intravenous administration of glucose.
Weight gain also results in due to increased food intake to combat symptoms of hypoglycemia. Other symptoms include giddiness, dizziness, syncopal attacks, blurring of vision and diplopia in severe hypoglycemic state.
In extremely severe conditions, epilepsy, semi consciousness and coma may also result in.
Lab Investigations
The most reliable method of diagnosing insulinoma involves a monitored 72 hours fast. A ratio of plasma insulin to glucose greater than 0.3 and increased ratio of pro-insulin to insulin (more than 20%) is diagnostic.
Immunoassay method reveals very high serum insulin level. Circulating C-peptide levels are also elevated.
Ultrasound and CT scan of abdomen demonstrate the tumour if it is more than 2 cm. CT scan is helpful in localizing tumour. Selective angiography is done in case of vascular tumours.
Treatment
Definitive therapy is accomplished by surgical extirpation (procedure of choice is enucleation). If no tumour is detectable, stepwise pancreatectomy is performed. Due to its malignant potential, treatment is exploration and excision. Surgical intervention includes resection of the tumour and if necessary distal pancreatectomy. Drug therapy includes hyperglycemic agents to correct hypoglycemia.
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