Hereditary fructose intolerance

Hereditary fructose intolerance ( HFI ) is a rare disease that is caused by an inherited disorder of fructose metabolism in fructose (fruit sugar) can not be broken down in sufficient quantities or not. As a result, the fructose content in the cells with a toxic effect is increased, which in turn interferes with the metabolism of glucose, causing hypoglycemia. It must not be confused with the much more common intestinal fructose intolerance fructose malabsorption due. The incidence of hereditary fructose intolerance is only 1:130.000, while about 30-40% of Europeans are affected by the fructose malabsorption, about half of them with symptoms.

Operation

Hereditary fructose intolerance is a very rare enzyme deficiency that affects the Fructoseabbau in the liver. Aldolase B, which normally cleaves the fructose -1-phosphate to dihydroxyacetone phosphate and glyceraldehyde, is missing. Instead, only the aldolase A is present, an enzyme of glycolysis, the substrate fructose-1 ,6 - bisphosphate, and fructose -1-phosphate is cleaved with fifty times lower speed.

The first enzyme of the Fructoseabbaus that Ketohexokinase is not affected, so the fructose enters the liver cell, is phosphorylated and the cell can no longer leave. Due to the enzyme defect, the fructose -1-phosphate but can not be cleaved, it accumulates in and inhibits enzymes of glycolysis, gluconeogenesis, and glycogen metabolism. The already mentioned aldolase A is concerned, as well as the fructose -1 ,6- bisphosphatase gluconeogenesis and glycogen. Hypoglycämien may thus be the result, as in starvation the glycogen is then broken down no longer, or only reduced and no glucose from amino acids or glycerol can be formed.

Methods of investigation

The proof is carried out, for example, by genetic testing. This should definitely be done ( the test for intestinal fructose intolerance ie ) in front of a fructose load test, as the latter in the case of very rare hereditary problems of fructose intolerance ( HFI ) can be perilous: the present at HFI enzyme deficiency in the liver would cause recorded fructose is not degraded and would in the blood glucose, blood sugar displace, whereupon the respondent could fall into a coma.

Therapy

This disease can not be medically, but treated only by a strict low-fructose diet. In some cases, the FI has improved by strict low-fructose diet.

Earlier in the intensive care used for parenteral nutrition FGX infusions ( fructose, glucose and xylitol ) are no longer used due to incompatibility in patients with fructose intolerance or Xylitintoleranz.