Enzymatic Defects as Causes of Hypoglycemia

Abstract

A review of some of the enzymatic causes of hypoglycemia is presented. Evidence that there may be a diminished production of epinephrine or glucagonin certain cases of hypoglycemia is reviewed and the relationship of these hormones to the activation of glycogen phosphorylase is discussed. Galactosemia, fructose intolerance and glycogen storage diseases are cited as examples of hereditary disorders attributable to specific enzyme defects and often accompanied by hypoglycemia. The deficiencies of galactose-1-phosphate uridyl transferase in galactosemia and aldolase in fructose intolerance result in the accumulation in the tissues of toxic quantities of intermediary metabolites (galactose-1-phosphate and fructose-1-phosphate, respectively) which secondarily affect the activities of other enzymes. In Type I glycogenosis, the hypoglycemia is explained by the deficiency of glucose-6-phosphatase. Other types of glycogenoses often provide examples of intermittent hypoglycemia. The role of gluconeogenesis in the maintenance of blood sugar levels has not been reviewed.