25 July 2009

Hypoglycemia in Hereditary Fructose Intolerance

What are the specific reasons for hypoglycemia seen in hereditary fructose intolerance?

Hereditary fructose intolerance (HFI) an autosomal recessive disorder in which there is subnormal activity of the enzyme fructose 1-phosphate aldolase B (1;2). Largely found in the liver, the enzyme is needed for normal fructose metabolism for splitting fructose 1-phosphate to form dihydroacetone and glyceraldehyde (1).

Hypoglycemia after consumption of fructose (also sucrose or sorbitol) results because of the lack of maintenance of proper blood glucose levels by the liver (2). The fructose ingestion and the lack of aldolase B results in the accummulation of fructose 1-phosphate in cells, particularly in the liver (1). The accumulation leads to depletion of Pi, which in turn keeps mitochondria in hepatocytes from producing ATP causing cell damage, and inhibition of glycogenolysis and, thus, guconeogenesis (1;2).

HFI often goes unrecognized and is life-threatening due to hypoglycemia along with possible liver and renal failure (3;4). Many of patients afflicted with the disorder have a noted distaste for sweet foods due to having suffered symptoms early in life such as vomiting and abdominal pain (2-4). The cure for HFI is exclusion of sources of fructose from the diet (1-4).

Reference List

1. Devlin TM. Textbook of Biochemistry with Clinical Correlations. Philadelphia: Wiley-Liss, 2002, pp 597 & 643.
2. Shils ME, Shike M, Ross AC, Caballero B, Cousins RJ. Modern Nutrition in Health and Disease. Baltimore, MD: Lippincott Williams & Wilkins, 2009.
3. Yasawy MI, Folsch UR, Schmidt WE, Schwend M. Adult hereditary fructose intolerance. World J Gastroenterol 2009;15:2412-3.
4. Cox TM. Hereditary fructose intolerance. Baillieres Clin Gastroenterol 1990;4:61-78.

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