Type I Glycogen Storage Disease: A Metabolic Basis for Advances In Treatment

Abstract

Studies suggest that the clinical and biochemical abnormalities present in GSD-I result from an excess rate of glycogenolysis secondary to a decrease in blood glucose concentrations below 70 mg/dl. The lack of glucose-6-phosphatase activity prevents hepatic release of glycogen to glucose and continued stimulation of glycogenolysis causes excessive formation of glucose-6-phosphate and secondarily increases lactate, triglyceride and uric acid. In addition, abnormal platelet function, prolonged bleeding time and impaired growth are prominent features of the illness. Biochemical and clinical aberrations in GSD-I can be substantially improved by treatment aimed at decreasing the hepatic stimulus for glycogenolysis by maintenance of blood glucose concentration between 70 and 150 mg/dl. This is most effectively done by total parenteral nutrition or continuous intragastric infusion of a high-glucose diet (i. e., Vivonex High Nitrogen or Precision LR). The equally effective, more practical and most acceptable method of maintaining blood glucose levels is continuous infusion of the diet at night for 8-12 hours, followed by high-starch feedings every 3 hours while awake. This treatment has been very effective in providing the necessary milieu for normal growth and development in 7 patients for 4 years.