A Case of Macroenzyme Aspartate Aminotransferase Mimicking Hepatic Injury

Macroenzymes are high molecular weight complexes that are formed by the binding of normal serum enzymes with circulating immunoglobulins - primarily IgG, IgA, and IgM. These high molecular weight complexes are difficult to clear through the kidneys, therefore they remain persistently elevated in the serum leading to inaccurate diagnoses and unnecessary workup. The prevalence of macroenzymes is relatively rare in the general population; however, it is an important phenomenon to be aware of when working up isolated elevations in serum enzymes. A quick and efficient test for the detection of macroenzymes is the polyethylene glycol precipitation test. Here, we present a case of macro-aspartate aminotransferase masquerading as an underlying hepatobiliary disease ultimately leading to an extensive evaluation before arriving at the correct diagnosis. This case highlights the importance of an accurate and efficient diagnosis of macroenzymes in the serum in order to prevent unnecessary healthcare utilization and also to decrease the psychological burden on the patient.