Which of the following is not a typical cause of elevated AST levels?

Elevated levels of aspartate aminotransferase (AST) in the blood are typically associated with a variety of conditions that involve tissue damage, particularly those affecting the liver, heart, or muscle. When exploring these conditions, myocardial infarction and muscle injury are well-known causes of elevated AST due to the release of the enzyme from injured tissues.

Myocardial infarction leads to the death of heart muscle cells, releasing AST into the bloodstream. Similarly, muscle injury from trauma or conditions like rhabdomyolysis also results in elevated AST as muscle cells break down. Pyridoxine deficiency can lead to elevated AST levels due to its role in transamination, where the enzyme is involved; thus, inadequate levels of the vitamin may cause an abnormal increase in AST as well.

In contrast, chronic kidney disease is not a typical direct cause of elevated AST. While kidney dysfunction can influence overall metabolism and might indirectly raise liver enzymes, the primary enzyme elevation commonly associated with kidney disease is often alanine aminotransferase (ALT) rather than AST. Therefore, elevated AST levels are not a characteristic finding in chronic kidney disease, distinguishing it from the other conditions listed.