False-Positive Troponin in a Professional Cyclist: A Case Report on Avoiding Misdiagnosis and Unnecessary Restrictions

Abstract Background Myocarditis can cause sudden cardiac death in athletes, and in the presence of clinical symptoms and elevated troponins, exercise restriction is recommended. However, macrotroponin complexes, formed by antitroponin antibodies, can cause falsely elevated troponin levels, thereby complicating the diagnostic process and leading to unnecessary exercise restriction. Case summary A 27-year-old professional cyclist presented with exercise intolerance following a viral illness. High-sensitivity troponin I was markedly elevated, while high-sensitivity troponin T remained normal. Major cardiac causes were excluded, raising suspicion for macrotroponin complexes. This was confirmed via polyethylene glycol (PEG) precipitation. The patient was cleared to return his sport activities without the need for further monitoring. Discussion In athletes, exercise-induced troponin release is common and may contribute to a higher prevalence of macrotroponin formation, which is an underrecognized cause of elevated troponin levels. A discrepancy between troponin I and T assay results can suggest its presence, which can be confirmed using polyethylene glycol precipitation, a simple method that helps avoid unnecessary testing, activity restrictions, and prolonged monitoring.