Falsely elevated cardiac troponin I levels

Abstract

The measurement of cardiac troponins (cTn) is of considerable usefulness in the diagnosis of acute coronary syndrome. Abnormal levels of serum cTn are occasionally found in patients who are not suffering a myocardial infarction. This may be observed in several well-known situations including pulmonary embolism, pericarditis, myocarditis, coronary vasospasm, sepsis, congestive heart failure, supraventricular tachycardia with hemodynamic compromise, re-nal insufficiency, and prolonged strenuous endurance exercise. Endogenous antibodies such as heterophile antibodies, rheumatoid factor, and other autoantibodies are known to interfere with the immunoassay measurements of many different analytes, including the widely used Abbot AxSYM cTnI analyzer. Other sources of circulating antibodies include immunotherapies, vaccinations, or blood transfusions that may interfere with these immunoassays as well. We examine the case of a 48-year-old man with a history of hypercholesterolemia and obesity who presented with chest pain and was found to have elevated Tn I levels on two separate occasions. Further work-up revealed that the Tn I levels were spuriously elevated because the patient's blood revealed a normal cTnI level when mixed with polyethylene glycol to inactivate any antibodies interfering with the cTnI assay.