Enzymes are proteins produced within cells that enable them to carry out their metabolic and biological functions. Muscle cells contain a variety of enzymes with particularly high concentrations of those involved in generating energy to power the muscles. When muscle cells are damaged, these enzymes leak into the bloodstream and may causes elevated levels. A variety of diseases and conditions can cause high muscle enzyme levels. Some are temporary and pose no long-term health risk but others are potentially life threatening.
Muscle Diseases and Conditions
A variety of muscle diseases and conditions can elevate muscle enzyme levels. Vigorous or strenuous physical activity -- particularly if you're unaccustomed to it -- can transiently increase muscle enzyme levels. Muscle trauma due to participation in contact sports or an accident also commonly causes a temporary elevation in muscle enzyme levels. In most cases, transient muscle enzyme level increases related to overexertion or mild muscle injuries pose no long-term health risk.
Certain muscle diseases are associated with elevated muscle enzyme levels, reflecting underlying muscle damage. Examples include:
- Inflammatory muscle diseases, such as polymyositis and dermatomyositis
- Muscular dystrophies, such as Duchenne type
- Toxic myopathies, which can occur with heavy alcohol use and certain illicit drugs including heroin, cocaine, amphetamines and phencyclidine (PCP)
Many systemic diseases -- those that have widespread effects in the body -- lead to deleterious effects on the muscles that can provoke muscle enzyme elevations. Examples include:
- Infectious diseases: influenza, HIV and certain parasitic infections
- Hormonal diseases: thyroid disorders, overactive adrenal glands or adrenal insufficiency, parathyroid disorders and diabetes
- Autoimmune diseases: rheumatoid arthritis and systemic lupus erythematosus
- Cancer: melanoma, non-Hodgkin lymphoma, and cancers of the lung, gastrointestinal tract, breast, kidney and prostate
There are other potential causes of elevated muscle enzyme levels. An example of particular concern is a heart attack, in which a sudden blockage in blood supply to the heart leads to death of heart muscle cells in the affected area. While most heart attacks cause chest pain or discomfort, some do not. These so-called silent heart attacks are sometimes detected due to elevated muscle enzyme levels.
Some prescription medications can also elevate muscle enzymes levels, although usually not dramatically. Examples include cholesterol-lowering statin medications, and certain medicines for heart disorders, Parkinson disease and HIV, among others.
Additional possible causes of elevated muscle enzyme levels include:
- Recent generalized seizure, intramuscular injections or surgery
- Multiple wasp or bee stings
- Peripheral artery disease, especially affected the leg muscles
- Malignant hyperthermia, which is a rare complication of general anesthesia
- Certain inherited metabolic or enzymatic disorders
Considerations, Warnings and Precautions
The term muscle enzymes is somewhat misleading as the enzymes that occur in muscles also occur in other body tissues. Therefore, elevated levels of so-called muscle enzymes might actually be due to a disease or disorder affecting another type of tissue or organ, such as the liver, brain or kidneys. Determining the cause of elevated muscle enzymes usually involves additional blood tests. Your doctor might also order other diagnostic tests.
See your doctor without delay if you experience muscle-related signs and symptoms, such as weakness, pain, soreness or muscle wasting. Seek emergency medical care if you experience difficulty breathing or muscle weakness that develops rapidly.
Reviewed and revised by: Tina M. St. John, M.D.