The AxSYM System Analyzer (Abbott Laboratories, Abbott Park, IL) is frequently utilized in the measurement of cardiac enzymes, hormones, drugs, and other markers. Falsely increased troponin I (TnI) results attributable to the presence of heterophilic antibodies (1), rheumatoid factor (2), or fibrin clots (3) have been described previously. We report several cases of erroneously increased results for plasma TnI that were attributable to a temporary malfunction of the AxSYM analyzer. The impairment of the analyzer was noted during one of the daily control runs when the three plasma TnI and creatine kinase-MB (CK-MB) quality-control samples repeatedly exceeded their respective control ranges. The instrument did not display an error code for a mechanical or other problem. In an effort to ascertain the cause of the spurious quality-control result, we opened the instrument cover to inspect the processing center. We checked the positions of two bulk solution dispensers (located within the AxSYM processing center). The dispensers, labeled “1” and “3”, were side-by-side, adjacent to the microparticle enzyme immunoassay (MEIA) optical assembly, processing center pipette, and processing carousel. Upon more …