Clinical Impact of Macrotroponin on Immunometric Troponin Assays: A Cross-Analytical Case Evaluation.

High-sensitivity cardiac troponin assays are susceptible to analytical interferences, including macrotroponin, an immunoglobulin-bound complex that may cause persistent, non-dynamic, and assay-dependent elevations. This paper describes the case of a 74-year-old woman with hypertension who presented with intermittent mild chest discomfort and exertional dyspnea and exhibited persistently elevated but stable cardiac troponin I concentrations over several months, in the absence of clinical, electrocardiographic, or imaging evidence of myocardial injury. Orthogonal testing revealed discordant results across different assay platforms, and polyethylene-glycol (PEG) precipitation resulted in a substantial signal reduction, confirming macrotroponin as the source of assay-dependent analytical interference. Recognizing this phenomenon is crucial to avoid misdiagnosis, unnecessary diagnostic procedures and inappropriate management in patients with isolated troponin elevation. In conclusion, this report provides evidence-based recommendations on the optimal diagnostic strategies and laboratory approaches to adopt in cases of suspected macrotroponin-mediated interference in high-sensitivity cardiac troponin assays.