University of Virginia case conference. Macroamylase, macro creatine kinase, and other macroenzymes

The importance of macroenzymes has become increasingly apparent in recent years (1,2). Macroamylase (EC 3.2.1.1) and macro CK (EC 2.7.3.2) are the macroenzymes most commonly noted in the clinical laboratory, and they are frequently responsible for diagnostic confusion. Several methods are available for the confirmation and analysis of macroenzymes, many of which require expensive equipment or complicated techniques. In this report we summarize two cases of macro creatine kinase and two cases of macroamylase that illustrate the clinical importance of recognizing these macroenzymes. We review the features of these macroenzymes, discuss their laboratory evaluation, and describe a simple method that we have used to detect the macroenzymes in these (and other) patients at our institution. Finally, we review the literature on other, less commonly observed macroenzymes in human blood. We stress (a) the impact of methodology on clinical impressions and (b) the importance of discussing laboratory observations with the patient's physician and communicating them to the patient's medical record in writing.