This case highlights the importance of considering assay interference, such as from rheumatoid factor, when troponin elevation is inconsistent with the clinical picture of ischemia.
hs-TnI assay interference by rheumatoid factor may cause false positives; leaves open systematic evaluation of prevalence in discrepant cases.
A 78-year-old woman presented twice with high sensitivity troponin I (hs-TnI) elevation. Two cardiac catheterizations showed nonocclusive coronary artery disease, and 2 cardiac magnetic resonance imaging scans were normal. With these investigations unable to explain the troponin I (hs-TnI) elevation, alternate troponin samples were sent to check for assay interference. Results from these troponin assays were low. With the patient having elevated rheumatoid factor as a potential contributor to assay interference, the lab reanalyzed the samples using heterophile antibody blocking tubes, revealing lower hs-TnI levels. This case serves as a reminder to consider assay interference when the clinical picture is inconsistent with ischemia.
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Saunders et al. (2021) studied this question.
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