Serum enolase and pyruvate kinase activities in the diagnosis of myocardial infarction.

Sequential determinations of serum enolase and pyruvate kinase (PK) activities were carried out in addition to routine enzyme assays on 191 patients admitted to a coronary care unit. The upper reference values established in 61 healthy laboratory staff members were 21 U/1 for enolase and 76 U/1 for PK. Of 99 patients with a confirmed diagnosis of myocardial infarction (MI), 97 manifested raised serum enolase during the period of observation; 85 of these patients had raised serum PK. The incidence of raised values for serum PK among patients considered not to have sustained infarction was similar to that shown by the routine enzymes, but serum enolase activity was much more frequently raised in these patients. The time-course of elevation of serum enolase and also that of PK are discussed in relation to the changes in other serum enzymes routinely measured for MI.