Disorders of fructose metabolism.

There are fundamental differences between the metabolic fate of fructose and of glucose. Whereas the metabolism of glucose is controlled by hormones such as insulin, fructose uptake and phosphorylation in the liver occurs independently of hormones and its ultimate metabolic fate is unpredictable. Essential fructosuria, a harmless inherited anomaly of fructose metabolism, is the least harmful of the disorders of fructose metabolism. Hereditary fructose intolerance and fructose-1,6-diphosphatase deficiency are discussed in greater detail with regard to biochemical abnormalities and clinical aspects. HFI is most serious in bottle-fed infants who cannot reject their sucrose-containing diet. Patients with HFI will have no clinical symptoms if kept on a fructose-free diet. In contrast, patients with fructose-1,6-diphosphatase deficiency can tolerate frucose. However, severe infections precipitate attacks of hypoglycaemia and lactic acidosis.