Clinical and Interpretive

Measurement of myoglobin is useful in assessing muscle damage from any cause. Myoglobin is a heme protein found in smooth and skeletal muscles. Serum myoglobin reflects a balance between intravascular release of myoglobin from muscle and renal clearance.

Previously serum myoglobin had been advocated as a sensitive marker for early acute myocardial injury (eg, acute myocardial infarction: AMI). However, more recent studies indicate that other newer markers (eg, troponin) provide superior diagnostic utility in detecting early myocardial injury.

Elevation of serum myoglobin may occur as a result of muscle trauma, resuscitation, myopathies, AMI, shock, strenuous body activity, or decreased elimination during renal insufficiency. Extreme elevations occur in rhabdomyolysis. Elevated myoglobin levels are seen in conditions of acute muscle injury. Elevation is nonspecific for acute myocardial infarction. The test is of no value in this regard in the presence of renal failure, rhabdomyolysis, extensive trauma, acute peripheral vascular occlusion, or after seizures.

Results are unreliable in lipemic serum; specimens that cannot be cleared by ultracentrifugation will be rejected.