Hereditary fructose intolerance
Hereditary fructose intolerance: Excerpt from Professional Guide to Diseases (Eighth Edition)
Hereditary fructose intolerance is an inability to metabolize fructose. After fructose is eliminated from the diet, symptoms subside within weeks. Older children and adults with hereditary fructose intolerance have normal intelligence and apparently normal liver and kidney function.
Causes and incidence
Transmitted as an autosomal recessive trait, hereditary fructose intolerance results from a deficiency in the enzyme fructose-1-phosphate aldolase. The enzyme operates at only 1% to 10% of its normal biological activity, thus preventing rapid uptake of fructose by the liver after ingestion of fruit or foods containing cane sugar.
In some European countries, hereditary fructose intolerance may have an incidence as high as 1 in 20,000 people.
Signs and symptoms
Typically, clinical features of hereditary fructose intolerance appear shortly after dietary introduction of foods containing fructose or sucrose. Symptoms are more severe in infants than in older people and include hypoglycemia, nausea, vomiting, pallor, excessive sweating, cyanosis, and tremor. In neonates and young children, continuous ingestion of foods containing fructose may result in failure to thrive, hypoglycemia, jaundice, hyperbilirubinemia, ascites, hepatomegaly, vomiting, dehydration, hypophosphatemia, albuminuria, aminoaciduria, seizures, coma, febrile episodes, substernal pain, and anemia.
Diagnosis
A dietary history often suggests hereditary fructose intolerance.
Confirming diagnosis A fructose tolerance test (using glucose oxidase or paper chromatography to measure glucose levels) usually confirms the diagnosis. However, liver biopsy showing a deficiency in fructose-1-phosphate aldolase may be necessary for a definitive diagnosis.
Supportive values may include decreased serum inorganic phosphorus levels. Urine studies may show fructosuria and albuminuria.
Treatment
Treatment of hereditary fructose intolerance consists of exclusion of fructose and sucrose (cane sugar or table sugar) from the diet. Otherwise, treatment is supportive as the patient’s progress is monitored.
Special considerations
❑ Tell the patient to avoid fruits containing fructose and vegetables containing sucrose (sugar beets, sweet potatoes, and peas), because sucrose is digested to glucose and fructose in the intestine. Fruits containing the least amount of fructose include strawberries, blackberries, blueberries, oranges, and grapefruits; others low in fructose are cherries, pears, bananas, grapes, and apples.
❑ Refer the patient and his family for genetic and dietary counseling as appropriate.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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