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Acute Care™ Myoglobin–Earliest Marker
For patients in need of an early diagnosis, a rapidly appearing biochemical marker (such as Myoglobin) plus a specific marker that rises later (e.g., cTnI) are recommended.1 In addition, Myoglobin has an excellent negative predictive value in the evaluation of patients with acute chest pain.2-6
Myoglobin, a low molecular weight heme protein found in cardiac and skeletal muscle, is valuable in the early evaluation of chest pain patients. It may appear in the blood in abnormal levels as early as 1 to 3 hours after onset of myocardial ischemia. While Myoglobin is not specific to cardiac muscle, it is useful in the detection of MI in the absence of skeletal muscle trauma or other factors that may be associated with a noncardiac-related increase.
Obtaining serial Myoglobin results can help aid in the earlier identification of an MI. In clinical studies, Myoglobin levels that doubled within 1 to 2 hours of presentation were determined to be highly specific indicators for AMI.7 The discriminatory power of Myoglobin is also improved when using the Δ 40 criterion4 (a difference of 40 ng/mL or more between the values at presentation and one hour after arrival in the ED).
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