The value of radioimmunoassay of myoglobin in the diagnosis of acute myocardial infarction.

Thirty-one patients with acute myocardial infarction (AMI) or doubtful AMI, admitted to the coronary care unit (CCU), were selected for study of serum myoglobin (Mb). In 22 cases with AMI a sequential study of serum Mb shows that it begins to rise 2-3 hours after the onset of the AMI. The average value for the first blood sample taken within 12 hours after the onset was 268.7 +/- 57 ng/ml (ranging from 86-800), and the elevation within 24 hours averaged 2.4-5.0 times the normal value. They were distinctly higher than those of SGOT (0.6-2.1), CPK (2.0-3.4) and LDH (0.6-1.9). Taking into account the peak values determined within 12 hours, Mb showed a 100% correlation with the diagnosis, CPK 85.7% (12/17), GOT 35.9% (6/17) and LDH showed a 13.3% (2/15) correlation. In patients with angina pectoris and old MI, serum Mb was within the normal range, suggesting that the determination of serum Mb is of practical value in the differential diagnosis of angina pectoris and AMI.