Normal Values Of Muscle Enzymes

Your muscles use many enzymes to control the chemical reactions that make them able to function. The same enzymes are present in your heart muscle and the skeletal muscles that make you able to move your body. When these muscles become damaged by strenuous exercise, injury, heart attack, or a medical condition such as myositis, muscle enzyme levels in your blood become elevated. Doctors use blood tests to diagnose some muscle problems, and exercise scientists use muscle enzyme tests to study athletic performance.

Creatine Phosphokinase

Creatine phosphokinase, or CPK, helps cause a reaction that turns the amino acid creatine into phosphate, which your muscle cells can use for quick energy. You use large amounts of CPK during strenuous exercise. Most of the CPK in your body is stored within your muscle tissue, so too much CPK in your blood can mean that your muscles have been damaged. Elevated CPK also occurs during a heart attack. The normal range of CPK in the blood for adults is 22 to 198 U/L, or units per liter.

Serum Glutamic Oxaloacetic Transaminase

Serum glutamic oxaloacetic transaminase, also called aspartate aminotransferase or SGOT/AST, is an enzyme that is present in your muscles and liver. Your body needs SGOT/AST to metabolize amino acids, which are the building blocks of proteins. The skeletal muscles that move your body and the cardiac muscles in your heart both contain SGOT/AST. Elevated levels of SGOT/AST can indicate a recent heart attack, muscle damage, or liver problems. The normal range for SGOT/AST levels in the blood is 20 to 30 U/L.

Lactate Dehydrogenase

Lactate dehydrogenase, or LDH, is an enzyme that is present in all the cells of your body. Elevated LDH levels in your blood can result from damage to any part of the body. Your doctor would need to run other tests to determine the specific cause of elevated LDH in your blood. Since LDH levels rise during strenuous exercise, exercise physiologists sometimes use LDH levels to study muscle strain and damage due to exercise. The normal range for blood LDH is 105 to 333 international U/L.

Aldolase

Aldolase is an enzyme that your body uses for amino acid metabolism. If you are suffering from weakness, your doctor may test your blood aldolase levels to determine if the weakness is due to a problem in your nerves or your muscles, since nerve problems do not cause high aldolase levels. This test is not very useful in cases of chronic long-term muscle damage, however, because the aldolase in your muscles can become so depleted that it no longer becomes elevated in your blood. Normal blood aldolase levels are between 1 to 7.5 U/L.