Hyperinsulinism, focal

Hyperinsulinism, Focal

Hyperinsulinism, focal is a condition characterized by the overproduction of insulin by a localized area of the pancreas. This condition is a form of congenital hyperinsulinism, which is a rare genetic disorder that causes persistent hypoglycemia (low blood sugar levels) in infants and children.

Pathophysiology

Focal hyperinsulinism occurs when there is a localized area of abnormal pancreatic beta cells that secrete excessive amounts of insulin. These areas, known as focal lesions, are typically found in the pancreas and are caused by a somatic mutation in the ABCC8 or KCNJ11 genes. These genes encode subunits of the ATP-sensitive potassium channel in the beta cells, which plays a crucial role in insulin secretion.

In focal hyperinsulinism, the mutation leads to the dysregulation of insulin secretion, causing the beta cells in the focal lesion to secrete insulin inappropriately, even when blood glucose levels are low. This results in persistent hypoglycemia, which can be dangerous if not managed properly.

Diagnosis

The diagnosis of focal hyperinsulinism involves a combination of clinical evaluation, laboratory tests, and imaging studies. Key diagnostic steps include:

• Clinical Evaluation: Assessment of symptoms such as hypoglycemia, irritability, lethargy, and seizures in infants and children.
• Laboratory Tests: Measurement of blood glucose, insulin levels, and other metabolic markers during hypoglycemic episodes.
• Genetic Testing: Identification of mutations in the ABCC8 or KCNJ11 genes.
• Imaging Studies: Use of 18F-DOPA PET scan to localize the focal lesion within the pancreas.

Treatment

The primary treatment for focal hyperinsulinism is surgical removal of the focal lesion. This procedure, known as a partial pancreatectomy, involves the resection of the affected area of the pancreas. The goal is to remove the hyperactive beta cells while preserving as much normal pancreatic tissue as possible.

In some cases, medical management may be used temporarily to stabilize blood glucose levels before surgery. Medications such as diazoxide and octreotide can help suppress insulin secretion and manage hypoglycemia.

Prognosis

The prognosis for patients with focal hyperinsulinism is generally favorable if the condition is diagnosed early and treated effectively. Surgical removal of the focal lesion often results in the resolution of hypoglycemia and normal blood glucose regulation. However, ongoing monitoring is essential to ensure that blood glucose levels remain stable.

Also see

• Congenital hyperinsulinism
• Hypoglycemia
• Pancreas
• Insulin