Disorders of Fructose Metabolism

Abstract

Two inborn errors are known in the specialized pathway of fructose metabolism depicted in Fig. 8.1. Essential fructosuria is a completely harmless anomaly characterized by the appearance of fructose in the urine after the intake of fructose-containing foods. In hereditary fructose intolerance (HFI), fructose provokes prompt gastrointestinal discomfort and hypoglycemia upon ingestion, although sensitivity varies from patient to patient; it may cause liver and kidney failure when taken persistently and becomes life threatening when given intravenously. Fructose-1,6-bisphosphatase (FBPase) deficiency is usually also considered an inborn error of fructose metabolism although, strictly speaking, it is not a defect of the specialized fructose pathway. It is manifested by the appearance of hypoglycemia and lactic acidosis (neonatally or during fasting) and may also be life-threatening.