The Johns
Hopkins Arthritis Center provides a good explanation of creatinine kinase
(CPK).
CPK also called
creatine kinase (CK) is an enzyme (chemical) found specifically in muscle
cells. One form of CPK is found in heart muscle cells, another in the skeletal
muscle cells. CPK is also found in brain cells. When these cells are damaged
for any reason, the CPK is released into the blood and can be measured by a
blood test. If the heart CPK (CPK-MB) is elevated it can mean that the heart is
damaged which can occur in a heart attack or in conditions in which the heart
muscle is inflamed such as viral myocarditis. Skeletal muscle can be damaged in
trauma such as in severe injury to the muscles, or after intense exercise
causing an increase in the skeletal muscle form of CPK (CPK-MM). Certain drugs
such as cholesterol lowering drugs (statins) can damage muscle and elevate CPK.
Other causes are alcohol, viruses, hereditary conditions. Finally CPK can be
elevated in certain autoimmune diseases that cause inflammation in the muscle
such as polymyositis or dermatomyositis.
In the post on “Why is my CPK so high,” Terry Blytheway does
a good job of explaining CPK.
“Going back to basics,
there are three types of creatine kinase or isoenzymes in the body: CK-BB is
mainly produced by the brain and the smooth muscle; CK-MB is primarily produced
by the heart muscle; and most of CK-MM is produced by the skeletal muscle.”
He goes on to explain what higher than normal CPK might
indicate.
“…if the test reveals
that the level of creatine kinase circulating in the blood is higher than it
should be in normal conditions, then chances are that the human body in
question has suffered damage either to the muscle or the brain. In fact,
astronomical levels of creatine kinase are indicative of injuries,
rhabdodomyolysis, myocardial infarction, myocarditis, myositis, malignant
hypethermia, McLeod syndrome, neuroleptic malignant syndrome, and
hypothyroidism. If most of this sounds like gibberish to you, just remember
that a heart attack, a muscle disease or a stroke may result in abnormally
raised creatine kinase levels in the blood. Statin medications used to decrease
serum cholesterol levels may also be the culprit.”
If you are interested, below are links to other posts on CPK.
