A 42-year-old man has markedly elevated CK and AST after a crush injury. Which condition best explains these findings?

A 42-year-old man has markedly elevated CK and AST after a crush injury. Which condition best explains these findings?

• A. Crush Injury to the Thigh
• B. Cerebrovascular Accident
• C. Pulmonary Infarction
• D. Early Acute Hepatitis

Answer: (A)

The main concept: skeletal muscle injury releases intracellular enzymes into the blood. Creatine kinase (CK) is a highly sensitive marker of muscle damage, and aspartate aminotransferase (AST) is present in muscle as well as liver and heart. When a crush injury occurs, especially in a large muscle group like the thigh, extensive muscle cell rupture (rhabdomyolysis) dumps CK and AST into the circulation, producing markedly elevated levels. This pattern fits a crush injury to the thigh because the large volume of muscle damaged leads to a big release of these enzymes. In contrast, conditions like a cerebrovascular accident or pulmonary infarction involve other tissues and do not typically cause a pronounced rise in CK. Early acute hepatitis mainly elevates AST and ALT due to liver injury, not CK, so it wouldn’t explain a very high CK level.

The main concept: skeletal muscle injury releases intracellular enzymes into the blood. Creatine kinase (CK) is a highly sensitive marker of muscle damage, and aspartate aminotransferase (AST) is present in muscle as well as liver and heart. When a crush injury occurs, especially in a large muscle group like the thigh, extensive muscle cell rupture (rhabdomyolysis) dumps CK and AST into the circulation, producing markedly elevated levels.

This pattern fits a crush injury to the thigh because the large volume of muscle damaged leads to a big release of these enzymes. In contrast, conditions like a cerebrovascular accident or pulmonary infarction involve other tissues and do not typically cause a pronounced rise in CK. Early acute hepatitis mainly elevates AST and ALT due to liver injury, not CK, so it wouldn’t explain a very high CK level.