Serum myoglobin is a blood test used to determine muscle damage, including muscle damage to the heart such as occurs after a heart attack. Elevated serum myoglobin may also indicate skeletal muscle damage or a variety of other conditions.

The test measures the level of myoglobin found in a person’s serum (the liquid part of blood that has had the clotting elements removed). Myoglobin is a protein that is found in heart muscles and skeletal muscles throughout the body. When a muscle is damaged, myoglobin is released into the blood. Eventually, the substance is eliminated from the body through urine.

Normal myoglobin levels range from 0 to 85 nanograms per milliliter (ng/ml). Higher serum myoglobin levels mean that the patient has severe muscle damage somewhere in the body. This test has been largely replaced by other tests, such as those for cardiac enzymes.