Myoglobin

LAB105

"Routine venipuncture
Collect one 4.5ml  Light green top (lithium heparin) tube"

Refrigerate, stable 48 hours; stable 8 hours tightly stoppered at room temperature; freeze for longer storage.

Gross hemolysis, lipemia, or icterus; failure to follow proper collection/handling procedures, and stability requirements

Daily/STAT

"Within 24 hours
STAT: 1 hour"

Myoglobin   female  0.0-61.5 ng/mLMyoglobin   male   0.0-121.0 ng/mL

Myoglobin is a globular heme protein with a molecular weight of approximately 17,800 daltons located in the cytoplasm of both cardiac and skeletal muscle cells.1 Myoglobin is an early marker of myocardial necrosis. It is released into the bloodstream in a temporal pattern. 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. Myoglobin 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. Although myoglobin has the  highest negative predictive value of any of the cardiac markers at very  early time-points, the negative predictive value falls rapidly starting  at approximately 6 hours.  This fall in the negative predictive value is  due to the rapid clearance of myoglobin from the blood after myocardial necrosis.