CPK MM FRACTION, SERUM

CPK MM Fraction, Serum

What it is

The CPK MM Fraction, Serum test measures the level of the MM isoenzyme of creatine phosphokinase (CPK) in the blood. CPK is an enzyme found in muscle, brain, and heart tissues, and the MM fraction specifically reflects skeletal muscle activity. Elevated levels often indicate muscle injury, inflammation, or certain neuromuscular disorders.

Uses

This test is used to evaluate skeletal muscle damage, diagnose muscular dystrophies, monitor muscle inflammation (myositis, polymyositis), and assess recovery after trauma or surgery involving muscles. It also helps in differentiating between cardiac and skeletal muscle injury when performed alongside CPK MB and CPK BB isoenzyme tests.

Symptoms That May Lead to the Test

Doctors may order this test if you experience unexplained muscle weakness, persistent muscle pain, stiffness, swelling, dark-colored urine (suggesting muscle breakdown), or if you have a history of recent trauma, seizures, or intense exercise leading to suspected muscle damage.

Abnormal Results

High CPK MM Levels: May indicate muscle injury, strenuous exercise, rhabdomyolysis, inflammatory muscle disorders, muscular dystrophy, or trauma. Levels can also rise after intramuscular injections or certain medications (e.g., statins).

Low or Normal Levels: Generally considered normal, though very low CPK may sometimes be seen in reduced muscle mass or chronic muscle degeneration.

Risks

The test requires a standard blood sample from a vein. Risks are minimal, including mild discomfort, bruising, or dizziness at the needle site, which usually resolve quickly.