D-dimer assay interference detected by the discrepancy in D-dimer concentrations at different dilutions: a case report

This case report describes interference from heterophilic antibodies in D-dimer assay. The interference was suspected due to discrepancies between D-dimer concentrations in the original sample and diluted samples, as well as inconsistent clinical findings. The patient's medical history, laboratory results, and imaging studies were considered in the investigation. Heterophilic antibodies, likely developed during the SARS-CoV-2 infection, were identified as the probable cause of interference. The interference was confirmed through various methods, including dilution studies, blocking heterophilic antibodies, and comparing results with an alternative D-dimer method. This case highlights the importance of recognizing and addressing interference in D-dimer testing, emphasizing the need for collaboration between clinicians and laboratory specialists.