Evaluation of urinary myoglobin assay test for myocardial infarction.

Serial determinations of urinary myoglobulin, beta2-microglobulin and albumin, and of serum myoglobin, were performed in twenty-eight consecutive patients admitted to a coronary care unit. Patients with myocardial infarction (MI patients) all had higher serum levels of myoglobin then those with other diagnoses (OBS patients). Myoglobinuria occurred in 80% of MI patients and in half of the OBS patients. The appearance of myoglobin in urine was mainly accounted for by an impaired renal reabsorption of low molecular weight proteins. Measurement of urinary myoglobulin, in contrast to serum myoglobulin, is of little value for the diagnosis of myocardial infarction.