Fructose Metabolism and Related Disorders

These flashcards cover key concepts, enzymes, and disorders related to fructose metabolism and summarize the clinical case discussed in the lecture.

What is fructose primarily metabolized in the liver converted into during its metabolism?

Fructose is initially phosphorylated to form fructose 1-phosphate.

What enzyme is responsible for the phosphorylation of fructose in the liver?

Fructokinase is the major enzyme involved in the phosphorylation of fructose.

What is the rate-limiting step in fructose metabolism?

Aldolase B is the rate-limiting step for fructose metabolism.

What condition results from a deficiency in fructokinase?

Essential fructosuria, which causes fructose to appear in the urine.

What are the clinical consequences of hereditary fructose intolerance?

It can cause symptoms like hepatomegaly and fasting hypoglycemia due to accumulation of fructose 1-phosphate.

What differentiates essential fructosuria from hereditary fructose intolerance?

Essential fructosuria is benign with no clinical consequences while hereditary fructose intolerance has significant symptoms due to fructose 1-phosphate accumulation.

How does high fructose intake affect normal individuals versus those with hereditary fructose intolerance?

Normal individuals may accumulate fructose 1-phosphate but manage it, while those with hereditary fructose intolerance cannot and experience symptoms.

What dietary change helped alleviate the infant's symptoms in the clinical scenario presented?

Switching from breast milk (which contains lactose) to a formula containing sucrose (glucose and fructose) resolved the symptoms.

Why is a deficiency in an enzyme metabolizing pentose sugars unlikely to be the cause of the infant's symptoms?

Because pentose sugars are not involved in the symptoms presented and are not related to the energy generation needed.

What is the most likely diagnosis for the infant's symptoms after dietary change?

Intolerance to dietary galactose was likely the cause, alleviated by removing it from the diet.