Endocrine-induced forms of hypoglycemia

Hypoglycemia due to endocrine disorders commonly manifests itself during the newborn period or in early infancy. Hyperinsulinism accounts for more than 50% of all cases of persistent hypoglycemia occurring during the first year of life. The underlying cause of hyperinsulinism is probably a functional dysregulation of the B cells of the pancreas. These patients suffer from severe, sometimes life-threatening hypoglycemia during their first hours and days of life. Hypoglycemia cannot be prevented by a high carbohydrate supply exceeding the endogenous glucose production rate of the liver. The diagnosis of hyperinsulinism is established by an increased insulin concentration (above 10-12 mU/l) during hypoglycemia (blood glucose less than 40 mg/dl). Macrosomia of these newborns without a history of maternal diabetes supports the diagnosis. Most of the patients require a 90%-95% pancreatectomy in order to prevent severe brain damage, as medical and dietary treatment are ineffective. Hypoglycemia due to panhypopituitarism, growth hormone deficiency and inherited glucocorticoid deficiency also develops during early infancy, but can be discriminated from hyperinsulinism by one important criterion: hypoglycemia can be avoided by continuous glucose infusion dosed at the endogenous glucose production rate. If additional symptoms are lacking the diagnosis has to be established by the plasma concentrations of the different hormones and provocation tests.