HIGHLY ELEVATED LACTATE-DEHYDROGENASE LEVEL IN A HEALTHY INDIVIDUAL -A CASE OF MACRO-LDH

Macroenzymes are complexes of serum enzymes with a plasmatic protein. They have a higher molecular weight and a more prolonged serum half-li fe than those of unbound enzymes. Although macroenzymes may be found i n the serum of post-myocardial infarction patients, they are not usual ly associated with any specific disease. Their presence, however, can cause an elevation in the serum levels of an enzyme, possibly leading to errors in diagnosis. We report a patient with extremely elevated se rum levels of lactate dehydrogenase (LDH) due to the formation of comp lexes with immunoglobulin G. She had undergone a myriad of clinical ex aminations until the macroenzyme responsible for this finding was dete cted. We also review the literature on the clinical significance of ma cro-LDH. We propose that awareness of this rare and probably benign ph enomenon can spare the patient from the distress of exhaustive investi gations. (C) 1997 Wiley-Liss, Inc.