- Last Update On : 2013-01-27
Myoglobin is an oxygen carrying heme protein present in high concentrations in the cytoplasm of cardiac and skeletal muscle. Myoglobin has a molecular weight of 18,000 and constitutes 2% of total muscle protein. Because of its low molecular weight and high cellular concentration, elevated blood levels can theoretically be detected prior to other cardiac markers of ischemic injury. Increases may be seen within 2 hours after the onset of chest pain. Peak levels up to10 times the upper limit of normal are reached in 6 to 9 hours. Serum levels return to normal within 24 to 36 hours after infarction. False negative results may occur if myoglobin levels are measured <2 hours before or >24 hours after infarction.A positive myoglobin result within 2 to 12 hours after onset of chest pain needs confirmation, but a negative test is valuable in ruling out acute myocardial infarction.
Because myoglobin is present in both skeletal and cardiac muscle, elevated serum levels are not sp