Insulinoma Definition
An insulinoma is a tumour of the pancreas derived from the beta cells which while keeping the ability to synthesize and secrete insulin is autonomous of the normal feedback mechanisms.
Insulinoma Diagnosis
The diagnosis is suspected in a patient with symptomatic fasting hypoglycemia. The conditions of Whipple's triad need to be met for the diagnosis of "true hypoglycemia" to be made: 1) symptoms and signs of hypoglycemia, 2) concomitant plasma glucose level of 45 mg/dL (2.5 mmol/L) or less, and 3) reversibility of symptoms with administration of glucose.
Insulinoma Treatment
The management is surgical removal of the insulinoma. This may require removing part of the pancreas as well (Whipple procedure and distal pancreatectomy). Medications such as diazoxide and somatostatin can be used to hinder the release of insulin for patients who are not surgical candidates or who otherwise have inoperable tumours.
Insulinoma Symptoms and Signs
Patients with insulinomas typically develop neuroglycopenic symptoms. These include recurrent headache, diplopia, lethargy, and blurred vision, particularly with exercise or fasting. Severe hypoglycemia may result in seizures, coma, and eventually, permanent neurological damage. Symptoms arising from the catecholaminergic response to hypoglycemia (i.e. palpitations, tremulousness, tachycardia, sweating, hunger, anxiety, nausea) are not as common. Sudden weight gain (the patient can become massively obese) is occasionally seen.
Insulinoma Causes
The gene of MEN, an autosomal dominant disease, is known as MEN1 and maps to band 11q13. MEN1 is thought to act as a tumor suppressor gene.
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