Useful For

Myoglobin is a globular heme protein located in the cytoplasm of both cardiac and skeletal muscle cells.  Myoglobin is an early marker of myocardial necrosis.  Clinical studies have demonstrated detectable levels of myoglobin as early as 1 hour after the onset of symptoms, and peak levels within 4 to 5 hours.  It is a very sensitive marker for acute myocardial injury but due to its presence in both cardiac and skeletal muscle tissues, it is not a specific marker.  Damage to either muscle type will result in an elevated myoglobin value.  However, myoglobin is often used as a negative marker for acute myocardial infarction (AMI) since two consecutive results below the cutoff, along with other clinical information could be used to rule out a diagnosis of AMI.

Myoglobin levels may be elevated in many conditions, such as skeletal muscle trauma, skeletal muscle or neuromuscular disorders, cardiac bypass surgery, renal failure and strenuous exercise.  Factors that may aid in the diagnosis of myocardial infarction include the pattern of rise and fall in myoglobin concentrations, clinical history, ECG and other laboratory tests.  The triage of patients should be based on serial samples.