A clinical and laboratory approach used to elucidate discordant results of high-sensitivity troponin T and troponin I
Abstract
Background: Careful interpretation of discordant results in high-sensitivity troponin measurements is necessary in cases of suspect immunoassay interferences. We describe several procedures taken in a case of a polymorbid patient with chest pain, without clear evidence of myocardial necrosis and with increased high-sensitivity cardiac troponin T (hs-cTnT).
We checked the Vafaie's algorithm for the evaluation of suspect interference in troponin measurements. Methods: We conducted a case report analysis, additional measurements, a dilution test and pretreatment of plasma with blocking agents.
Results: Concentration of hs-cTnT (99th percentile of "healthy" population 14 ng/L) increased from 120.1 ng/L to 280.4 ng/L during an 8-month period and decreased to 216.3 ng/L during the following month with repeatedly negative troponin I (TnI), hs-cTnI, myoglobin and creatine kinase MB (CK-MB). Suspected false positivity of hs-cTnT was further confirmed by treatment of plasma with an antiheterophile blocking agent (hs-cTnT before treatment 280.4 ng/L, after 16.53/16.23 ng/L).
This outcome was further confirmed by the manufacturer's experiments. Conclusions: The false-positive results of hs-cTnT were caused by the presence of extremely rare high molecular weight protein, presumably IgM, most likely HAMA (human anti-mouse antibody).
Only the pre-treatment of plasma with a blocking agent provided a reliable indication of the interference. Cooperation among clinicians, laboratory personnel and the manufacturer is essential. (C) 2015 Elsevier B.V.
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