Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1084 page)

   Open heart surgery

   Carriers of progressive muscular dystrophy

   Extensive trauma

   Myocarditis

   Acute infectious diseases

   Seizure

   Toxin exposure: cocaine, narcotics, sea snake venom

   Malignant hypertension

   Limitations

   With high-sensitivity troponins and 99% sensitivity cutoffs now currently used in MI diagnosis, myoglobin has been replaced by troponin as the preferred cardiac biomarker. Exceptions may be in rapid ACS protocols if local laboratory point-of-care troponin is unreliable. Nevertheless, myoglobin should not be the solitary biomarker used for diagnosis.

   Increased values may occur with skeletal muscle damage, exhaustive exercise, or heavy alcohol abuse.

   The myoglobin test displays a low specificity for AMI. Myoglobin may come from either heart or skeletal muscle, so an increase in serum myoglobin is not specific for damage to the heart.

   Blood samples should be drawn every 2–3 hours for the first several hours after experiencing chest pain (myoglobin may be released in multiple short bursts) for accurate measurements.