Electrophoretic demonstration of three extra lactate dehydrogenase isoenzymes in the serum of a "normal" individual.

Five lactate dehydrogenase (LD; L-lactate:NAD oxidoreductase, EC 1.1.127) isoenzymes are demonstrated by electrophoresis in normal human serum. Altered activities of these isoenzymes have been associated with pathological conditions, so that their determination has become a useful diagnostic aid. Abnormal LD-isoenzyme patterns with one and two extra isoenzyme bands have been reported in serum samples of a few pathological cases associated with high LD activities(1-15). I report here an abnormal isoenzyme pattern with three extra isoenzyme bands in the serum of an apparently normal subject with normal totalLD activity.