Which CK isoenzyme is elevated in muscle diseases?

Which CK isoenzyme is elevated in muscle diseases?

• A. CK-MM
• B. CK-BB
• C. CK-MB
• D. CK-NN

Answer: (A)

The CK isoenzyme pattern reflects the tissue source of injury, and in skeletal muscle disease the enzyme released into blood comes mainly from muscle fibers. CK has three main forms: CK-MM is predominantly from skeletal muscle, CK-MB from heart, and CK-BB from brain. When muscle is damaged, the serum CK rises with CK-MM as the major elevated isoenzyme, so CK-MM becomes the most prominent CK elevation in muscle disorders. The other isoforms rise primarily with injury to their respective tissues (CK-MB for cardiac injury, CK-BB for brain), so they are not the typical markers for skeletal muscle disease.

The CK isoenzyme pattern reflects the tissue source of injury, and in skeletal muscle disease the enzyme released into blood comes mainly from muscle fibers. CK has three main forms: CK-MM is predominantly from skeletal muscle, CK-MB from heart, and CK-BB from brain. When muscle is damaged, the serum CK rises with CK-MM as the major elevated isoenzyme, so CK-MM becomes the most prominent CK elevation in muscle disorders. The other isoforms rise primarily with injury to their respective tissues (CK-MB for cardiac injury, CK-BB for brain), so they are not the typical markers for skeletal muscle disease.