CPK is the abbreviation for a blood test called creatine phosphokinase. CPK is an enzyme found primarily in muscles. This includes the muscles in the heart.

Any muscle injury or damage can cause a rise in the blood level of CPK. For example, a person would likely have a high CPK after a fall. A high CPK also occurs when someone has a heart attack.

Inflammation in the muscles, called myositis, will raise the CPK level. Usually people with myositis have aches and pains and muscle weakness.

Some people persistently have a CPK that is higher than normal because of decreased excretion of CPK through the kidneys. This is seen most often in people with kidney disease.

Today, taking a statin drug is one of the most common reasons for a high blood level of CPK. This occurs so commonly that doctors do not routinely order CPK blood tests when a person is taking a statin.

However, if you take a statin and have muscle aches, then a CPK blood test helps determine if you should stop the statin or lower the dose. A person taking a statin who has muscle aches and high CPK is at risk for developing a condition of severe muscle breakdown called rhabdomyolysis. This condition can result in kidney failure.

There are many other potential causes of high CPK. If you otherwise feel fine, your doctor might suggest a repeat CPK blood test before any additional evaluation needs to be done.