CK-MV is less than 6% and is associated with which CK isoenzyme?

• A. Mitochondrial CK
• B. CK-MM
• C. CK-BB
• D. CK-MV

Answer: (A)

CK-MV refers to the mitochondrial form of CK. This isoenzyme is located in mitochondria and typically makes up only a small fraction of total CK activity in serum—often less than 6%. The major CK forms in serum come from cytosolic CK enzymes: CK-MM from skeletal muscle, CK-MB from heart, and CK-BB from brain. Thus, a CK-MV fraction under 6% points to mitochondrial CK as the associated isoenzyme.