THE TOLBUTAMIDE TOLERANCE TEST IN THE EVALUATION OF CHILDHOOD HYPOGLYCEMIA

Abstract

The intravenous tolbutamide tolerance test has been evaluated in normal children and in children with ketotic hypoglycemia, idiopathic hypoglycemia, and the leucine-sensitive form of idiopathic hypoglycemia. Following tolbutamide administration to normal children, the concentration of blood glucose falls 26% below fasting levels within 15 to 30 minutes and returns to fasting levels at the end of 2 hours. This is similar to the response of normal adults. Some children with idiopathic hypoglycemia and with the leucine-sensitive form of idiopathic hypoglycemia have a prolonged hypoglycemic response to tolbutamide similar to that seen in patients with insulin secreting tumors. The tolbutamide tolerance test in children appears to be of little help in differentiating islet cell adenoma from leucine-sensitive, ketotic, or idiopathic hypoglycemia. Further evidence is presented that leucine and tolbutamide mediate insulin release from the pancreas by different mechanisms of action.