Macro lactate dehydrogenase (LD) due to protein binding of LD isoenzyme 1

Abnormal lactate dehydrogenase (LD) isoenzyme patterns apparently due to protein binding of LD-1 have been observed in a patient with hepatoma. The abnormal patterns were observed within 30 h of death but were preceded by normal LD isoenzyme patterns. Heat treatment of the abnormal specimens followed by addition of control serum reproduced the abnormal pattern. This is consistent with immunoglobulin binding of LD. Results such as those observed in this case could serve to confound the interpretation of LD isoenzyme analyses. The diagnostic significance of these results is not clear.