Troponin I interference in an 18-year-old patient with bradycardia: a case study

To investigate the cause of markedly elevated cardiac troponin I (cTnI) levels that were inconsistent with the clinical presentation in an 18-year-old male patient with bradycardia.

Serial dilution analysis, heterophile antibody blocking test (HBT), polyethylene glycol 6000 (PEG6000) precipitation, and recovery rate calculation were performed on the patient samples, and the experiments were repeated three times. Additionally, continuous monitoring of cTnI, cardiac troponin T, myoglobin, creatine kinase (CK) and CK-MB was conducted on the patient. The recovery rate in the control group was derived from 20 troponin-positive patients.

The serial dilution test showed good linearity. After HBT treatment, the cTnI concentration was 3744 ng/L, while the control tube was 4024 ng/L, showing no significant change. In contrast, cTnI decreased markedly to 142 ng/L after PEG6000 precipitation. The recovery rate was only 5.61%, which was significantly lower than the mean recovery rate of 53.33% observed in the control group.

The patient was ultimately diagnosed with falsely elevated cTnI caused by macrotroponin interference. This case suggests that when laboratory results are inconsistent with clinical findings, the possibility of analytical interference should be carefully considered, and effective communication between the laboratory and clinicians is essential to avoid misleading diagnostic and therapeutic decisions.