Which enzyme is most diagnostic for Duchenne muscular dystrophy?

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Multiple Choice

Which enzyme is most diagnostic for Duchenne muscular dystrophy?

Muscle injury in Duchenne muscular dystrophy causes leakage of intracellular enzymes into the blood, and the enzyme most indicative of this muscle-specific damage is creatine kinase. CK is highly concentrated in skeletal muscle (especially the CK-MM isoenzyme), so when muscle membranes are compromised, CK spills into the serum in very large amounts. This dramatic, early elevation is much more characteristic of a primary muscle disease than the other enzymes listed, which are also present in liver or other tissues and can rise due to non-muscle problems. ALT is more liver-focused, AST appears in heart and liver as well as muscle, and LDH is common to many tissues and conditions. Because of its strong muscle specificity and the typically enormous rise in Duchenne patients, CK is the best diagnostic marker for this condition, often prompting genetic confirmation of dystrophin mutations.

Muscle injury in Duchenne muscular dystrophy causes leakage of intracellular enzymes into the blood, and the enzyme most indicative of this muscle-specific damage is creatine kinase. CK is highly concentrated in skeletal muscle (especially the CK-MM isoenzyme), so when muscle membranes are compromised, CK spills into the serum in very large amounts. This dramatic, early elevation is much more characteristic of a primary muscle disease than the other enzymes listed, which are also present in liver or other tissues and can rise due to non-muscle problems. ALT is more liver-focused, AST appears in heart and liver as well as muscle, and LDH is common to many tissues and conditions. Because of its strong muscle specificity and the typically enormous rise in Duchenne patients, CK is the best diagnostic marker for this condition, often prompting genetic confirmation of dystrophin mutations.

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