Hereditary fructose intolerance
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An infant develops vomiting, hypoglycemia, and liver dysfunction after introduction of fruit/juice. Symptoms resolve when fructose is removed.
AR; ALDOB (aldolase B)
- Symptoms after fructose/sucrose/sorbitol exposure
- Hypoglycemia, vomiting, hepatomegaly
- Aversion to sweets (protective)
- Avoid IV solutions containing fructose
- Not on newborn screening; suspect from symptoms (vomiting, hypoglycemia, hepatomegaly) triggered by fructose/sucrose/sorbitol exposure
- Acute exposure causes hypoglycemia, hypophosphatemia, hyperuricemia, lactic acidosis, and abnormal liver/renal function
- Confirmatory ALDOB molecular testing (preferred); the fructose tolerance test is diagnostic but hazardous and largely replaced by genetic testing
- Reduced aldolase B activity on liver biopsy if molecular testing is inconclusive
- Fructose/sucrose/sorbitol-free diet
"ALdo B = A Liver enzyme": aldolase B is only expressed in the liver, which is why hepatomegaly and liver damage dominate. Fructose-1-phosphate accumulates and traps phosphate.
"He-Re-di-tary" = Hepatic, Renal function is Fruct'd up: liver and kidney are both affected.
Low "FuSS" diet: avoid Fructose, Sucrose (glucose + fructose), and Sorbitol (converted to fructose). "Fruit-toSS": toss out foods with fructose, sucrose, and sorbitol.
"Kinase = kinder": fructokinase (KHK) deficiency is essential fructosuria, a benign condition with isolated fructosuria. HFI (aldolase B) causes liver and kidney damage. Same pattern in the galactose pathway: galactokinase (GALK1) deficiency = cataracts only vs classic GALT galactosemia = severe. The first kinase step is the kinder deficiency in both sugar pathways.
This table lists the four disorders of fructose metabolism: "Fruit Sorbet Is Healthy". Fructose-1,6-bisphosphatase deficiency, Sorbitol dehydrogenase deficiency, Essential fructosuria (benign), and Hereditary fructose intolerance.
