The big picture: Creatine kinase (CK) is an enzyme that plays a key role in energy production by converting creatine into phosphocreatine, which provides energy for muscle contractions. CK is primarily found in skeletal muscles, the brain, and the heart. Measuring CK levels in the blood is important for assessing muscle damage, heart function, and overall muscle health. Elevated CK levels can signal muscle injury, inflammation, or certain conditions affecting the muscles, heart, or brain.

Role in muscle health: CK is vital for maintaining energy reserves in muscle tissues. When muscles are stressed or damaged, CK is released into the bloodstream, making it a useful marker for diagnosing muscle-related injuries or conditions. Elevated CK levels are often associated with muscle injury, intense physical activity, or conditions like rhabdomyolysis, muscular dystrophy, or inflammatory muscle diseases. Symptoms of elevated CK may include muscle weakness, pain, swelling, or stiffness.

Role in heart health: CK plays an important role in detecting heart damage, particularly following a myocardial infarction (heart attack). When heart muscle cells are damaged, they release CK-MB, a specific isoenzyme of CK, into the bloodstream. Elevated CK-MB levels are used to help diagnose heart attacks, as they rise shortly after the damage occurs and can remain elevated for several days. Elevated CK levels in the heart may also indicate other conditions, such as myocarditis or heart muscle inflammation.

High CK levels: Elevated CK levels are often associated with muscle injury, intense physical activity, or conditions like rhabdomyolysis, muscular dystrophy, or inflammatory muscle diseases. Symptoms of elevated CK may include muscle weakness, pain, swelling, or stiffness. In heart-related cases, high CK levels can indicate heart damage from a heart attack or myocarditis. If CK levels remain high, further tests may be needed to identify the specific muscle group or tissue affected, including CK isoenzymes testing.