How does Tarui disease differ from McArdle disease?

Tarui (GSD VII) causes both exercise intolerance from myophosphorylase block AND hemolytic anemia from erythrocyte PFK deficiency; McArdle has no hemolysis. Sucrose worsens Tarui (paradoxical effect).

Why does sucrose worsen exercise tolerance in Tarui disease?

Sucrose raises glucose-6-phosphate which inhibits the already-deficient PFK; glucose cannot enter glycolysis in muscle, paradoxically worsening the glycolytic block - the opposite of McArdle disease.

What is the out-of-wind phenomenon in Tarui disease?

Some Tarui patients do NOT experience second wind (unlike McArdle) because glucose cannot bypass the block; fatty acid oxidation provides the only late exercise fuel source.

What is the gout risk in Tarui disease?

Compensated hemolysis causes hyperuricemia; combined with purine nucleotide breakdown during exercise, gout risk is elevated; allopurinol may be needed in symptomatic hyperuricemia.

What dietary approach helps Tarui disease?

High fat/protein diet provides free fatty acids and ketones as exercise fuel; complex carbohydrates are better tolerated than simple sugars; pre-exercise lipid intake improves exercise capacity.

Tarui Disease (GSD VII) Exercise Tolerance Assessment

Assesses GSD type VII (phosphofructokinase deficiency / Tarui disease) using exercise intolerance score, hemolytic anemia severity (indirect bilirubin, reticulocyte count), and muscle CK during exertion.

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Frequently Asked Questions

How does Tarui disease differ from McArdle disease?

Why does sucrose worsen exercise tolerance in Tarui disease?

What is the out-of-wind phenomenon in Tarui disease?

What is the gout risk in Tarui disease?

What dietary approach helps Tarui disease?