[Isolated aspartate aminotransferase elevation in a young, healthy person. Case report]

The authors present diagnostic methods used in a young healthy person who had isolated aspartate aminotransferase elevation. Polyethylene glycol precipitation test, aspartate aminotransferase serum electrophoresis and immunofixation were performed for measuring the macro-aspartate aminotransferase. It was found that aspartate aminotransferase activity in the patient was almost completely eliminated after precipitation of immunoglobulins with polyethylene glycol. In addition, aspartate aminotransferase migrated in the control samples to the anode while in the patient towards the cathode. Finally, a wider and more intense staining band was visible in the region of immunoglobulin A in the patient sample on the immunofixation gel as compared to the control sample. The authors conclude that that increased aspartate aminotransferase activity was due to macro formation. The elevated level of immunoglobulin A and selective increase of polyclonal immunoglobulin A (κ and λ light chains) indicated that the macro format was created by immunoglobulin A bound to aspartate aminotransferase.