Myoglobin

Myoglobin is an intracellular heme protein that aids in the transport of oxygen. Oxygen binds to the porphyrin ring of myoglobin, as it does to hemoglobin, forming oxymyoglobin. Myoglobin is abundantly present in both cardiac and skeletal muscle.

Immunoassays detecting serum levels of myoglobin have long been used to confirm the diagnosis of myocardial infarction (MI). At approximately 17,500 Da, myoglobin is small enough to pass easily into circulation after cardiac injury, making it one of the earliest biochemical markers of MI. Serum myoglobin levels peak at approximately 6 to 9 hours post-MI, but return to normal within 24 to 36 hours as myoglobin is easily and rapidly cleared from circulation