The Hidden Threat in Immunoassays: A Case of Persistent False-Positive CK-MB.

Objective: This report aims to explore the significant impact of heterophilic antibodies on CK-MB immunoassays, leading to persistent false-positive results.

Case report: A 59-year-old male with a history of coronary artery disease exhibited persistently elevated CK-MB levels for over two years, despite normal troponin I levels. Further investigations, including serial dilution, blocking experiments, and testing across different platforms, confirmed the presence of heterophilic antibody interference, which was responsible for the falsely elevated CK-MB levels.

Conclusion: This case underscores the critical importance of recognizing heterophilic antibody interference in immunoassays. The use of appropriate diagnostic approaches, such as blocking antibodies, cross-platform testing, and the integration of additional diagnostic markers, is essential to prevent misdiagnosis and ensure accurate clinical decision-making.