Effect of Rheumatoid Factor on Cardiac Troponin I Measurement Using Two Commercial Measurement Systems

The Abbott AxSYM cardiac troponin I (cTnI) immunoassay may generate false-positive results in the presence of specific human anti-animal antibodies (HAAAs) (1). We use the term HAAAs rather than heterophile antibodies, a term used for weak, multispecific antibodies against diverse antigens (2), either human or animal. Techniques are available to detect and correct the interference attributable to HAAAs. We have used the Heterophile Blocking Tube (HBT; Scantibodies Inc.) to identify interference from suspected HAAAs. Anecdotal reports and experience in our laboratory have also suggested that the Abbott AxSYM cTnI may also be susceptible to interference from rheumatoid factor (RF), a heterophile antibody. Abbott Laboratories has recently modified its cTnI reagent system to address the issue of HAAA and heterophile antibody interference. The objective of this study was to compare the Beckman Access …