Disorders of Carbohydrate Metabolism

What enzyme deficiency leads to hereditary fructose intolerance?

When do symptoms of hereditary fructose intolerance commonly present?

What is a characteristic initial symptom of hereditary fructose intolerance?

Which disorder is characterized by an elevated level of plasma galactose-1-phosphate combined with galactosuria?

What are common symptoms of classic galactosemia in infants?

Which condition is differentiated from hereditary fructose intolerance by the gastrointestinal symptoms following large amounts of fructose ingestion?

At what point do glycogen storage diseases typically present?

What nutritional therapy is essential for managing hereditary fructose intolerance?

Disorders of Carbohydrate Metabolism

Disorders of carbohydrate metabolism vary in presentation, clinical course, and outcome.
Early and aggressive nutritional therapy is required for these disorders.

Hereditary Fructose Intolerance (HFI)

Results from a deficiency of the liver enzyme aldolase B.
Typically presents in infancy and toddlerhood, when dietary sources of sucrose and fructose are introduced.
Initial symptoms include nausea, bloating, and vomiting.
Untreated, liver and kidney damage can occur, along with growth restriction.
Incidence of about 1 in 20,000 to 30,000 in Europe.
Different from fructose malabsorption, which is a more common condition where individuals experience gastrointestinal symptoms after ingesting large amounts of fructose.

Galactosemia

Characterized by an elevated level of plasma galactose-1-phosphate combined with galactosuria.
Found in two autosomal recessive metabolic disorders: galactokinase deficiency and galactose-1-phosphate uridyltransferase (GALT) deficiency, also known as "classic galactosemia."
Illness generally occurs within the first 2 weeks of life.
Symptoms include vomiting, diarrhea, lethargy, failure to thrive, jaundice, hepatomegaly, and cataracts.
Infants with galactosemia may be hypoglycemic and susceptible to infection from gram-negative organisms.
If left untreated, death frequently ensues secondarily to septicemia.

Learn about various disorders of carbohydrate metabolism, including galactosemia, hereditary fructose intolerance, and glycogen storage diseases, and their different presentations and outcomes.