Creatine Kinase (CK) is an enzyme found predominantly in skeletal muscle, cardiac muscle, and brain tissue. In conditions like muscular dystrophy, muscle fiber damage leads to increased CK leakage into the bloodstream, making it a sensitive and specific marker for muscle injury. Elevated serum CK levels directly correlate with the extent of muscle damage, aiding in the diagnosis and monitoring of muscle disorders. Unlike other enzymes, CK is the most reliable enzyme to assess muscle cell integrity and differentiate muscular dystrophies from other clinical conditions.

Reference: Robbins Basic Pathology, Kumar, Abbas, Aster, 10th Edition.