Hereditary Fructose Intolerance

Question 1

What enzyme is deficient in hereditary fructose intolerance?

Answer 1

Aldolase B

Question 2

How do you diagnose hereditary fructose intolerance?

Answer 2

Respond to fructose withdrawal

DNA analysis in leukocytes (3 different genes), if negative need a liver biopsy to do enzyme analysis

Question 3

What are the typical symptoms in a neonate that is breastfed?

Answer 3

Trick question: there are none, because the babe is not ingesting foods with fructose/sucrose/sorbitol.

Question 4

What happens to individuals with hereditary fructose intolerance when they acutely ingest fructose containing foods?

Answer 4

Abdo pain, N/V, restlessness, pallor, sweating, trembling, lethargy, apathy, coma, jerks/convulsions (aka S/S hypoglycemia)

Question 5

What infants can present with acute symptoms of hereditary fructose intolerance?

Answer 5

those receiving cow’s milk formula sweetened with fructose or sucrose.

Question 6

Which solids typically are introduced and cause acute s/s of hereditary fructose intolerance?

Answer 6

First fruits and vegetables introduced while weaning from breastfeeding

Question 7

What symptoms can occur with chronic untreated hereditary fructose intolerance?

Answer 7

FTT, hepatomegaly, bleeding, jaundice, edema, ascites (aka sequelae of liver failure)

Question 8

What are characteristic lab findings in hereditary fructose intolerance?

Answer 8

1. Liver failure
2. Dysfunction of renal proximal tubules (Fanconi syndrome)
3. Hypoglycemia (typically short lived and may be missed)

Question 9

How do you treat hereditary fructose intolerance?

Answer 9

Eliminate fructose from the diet and medications. Replace with other sugars to ensure that the diet is not too high in fat content.

Question 10

What is the typical prognosis for hereditary fructose intolerance?

Answer 10

Most abnormalities disappear rapidly after fructose is removed from the diet. Hepatomegaly however can remain for years.