Radioimmunoassay of serum myoglobin in screening for acute myocardial infarction.

Over an 8-month period 289 patients consecutively admitted to a coronary care unit were studied to assess the value of serum myoglobin determinations by radioimmunoassay in screening for acute myocardial infarction. Of the 289 patients 127 (44%) had an infarction. It was found that when blood sampling was done within 5 to 15 hours after the onset of chest pain this assay had a sensitivity, specificity, and positive and negative predictive values of more than 97%. In this study healthy young adults had a mean serum myoglobin level of 37 +/- 11 (standard deviation) ng/ml, and values above 80 ng/ml were considered positive for acute myocardial infarction. False-positive results can be due to stock, vigorous exercise, skeletal muscle damage and several renal failure, but, except for the last one, these conditions also caused an increase in the serum level of the creatine kinase isoenzyme CK-MB.