Influence of hemolysis on the serum lactate dehydrogenase-1/lactate dehydrogenase-2 ratio as determined by an accurate thin-layer agarose electrophoresis procedure.

The accuracy of our lactate dehydrogenase (EC 1.1.1.27) isoenzyme procedure, based on electrophoresis in thin-layer agarose, has previously been assessed (Clin. Chem. 22: 1995, 1976). We now show that the method is similarly accurate and precise for the specific measurements of lactate dehydrogenase isoenzyme-1 and -2. We have also determined the lactate dehydrogenase isoenzyme pattern in peripheral erythrocytes and have found that lactate dehydrogenase-1 is usually the isoenzyme present in greatest concentration. Therefore, hemolysis may increase lactate dehydrogenase-1 in serum, affecting the lactate dehydrogenase isoenzyme ratio used in the diagnosis of myocardial infarction. This conjecture has been confirmed by in vitro experiments, and in a small group of patients with intra-vascular hemolysis.