The differential diagnosis of hyperinsulinism involves the consideration not only of tumors of the islet cells of the pancreas but also of all other causes of spontaneous hypoglycemia.1 Hypoglycemia may be due either to organic or to functional causes and must be suspected with a wide variety of symptoms.2 It is important to differentiate organic hypoglycemia and functional hypoglycemia, since in the former specific medical or surgical therapy is required, whereas in the latter dietary management usually gives excellent results.
The multiple causes of hypoglycemia require a brief review of the relationship of hyperinsulinism to other organs (Fig. 1). Organic hypoglycemia may be due to abnormalities of the liver, pituitary, adrenal glands, or pancreas. The liver is important in the storage and breakdown of sugars and in certain stages of parenchymal damage may cause hypoglycemia which simulates hyperinsulinism. Since the diagnostic criteria of liver disease are so well