[Two cases of false troponin I increase in patients with heterophile antibodies]

Cardiac troponin T and I are highly sensitive and specific biochemical markers for the detection of myocardial damage and they are now considered the preferred markers for the diagnosis of myocardial infarction. Despite this, in some cases elevations in the serum levels of cardiac troponin T and I are not associated with a final diagnosis of cardiac necrosis. These false-positive results are to be related to different interferences in immunometric assays. We report 2 cases of false-positive troponin I results due to heterophilic antibodies. Two women admitted to the Emergency Department with acute chest pain persistently showed, in serial blood samples, elevated and constant values of troponin I serum levels. The results were confirmed as being false positives by treatment of the samples with heterophilic blocking reagent (Scantibodies Laboratory, Santee, CA, USA). Coronary artery disease was excluded at coronary angiography and at stress testing in the first case and at stress myocardial perfusion imaging in the second case. In clinical practice, in case of persistently elevated but constant values of cardiac troponin without the time interval of release characteristic of acute syndromes, it is important to bear in mind the possible occurrence of false-positive cardiac troponin results due to the presence of heterophilic antibodies.