Janka Franeková1, Martin Bláha2, Jiří Bělohoubek3, Markéta Kotrbatá4, Peter Sečník5, Zdenek Kubíček6, Jiří Kettner7, Antonín Jabor8. 1. Department of Laboratory Methods, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic; Charles University, 3rd Faculty of Medicine, Ruská 87, 100 00 Prague 10, Czech Republic. Electronic address: jafa@ikem.cz. 2. Department of Cardiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic. Electronic address: martin.blaha@ikem.cz. 3. Department of Preventive Cardiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic. Electronic address: jiri.belohoubek@ikem.cz. 4. Department of Laboratory Methods, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic. Electronic address: marketa.kotrbata@ikem.cz. 5. Department of Laboratory Methods, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic. Electronic address: peter.secnik@ikem.cz. 6. Department of Laboratory Methods, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic. Electronic address: kubicek.zdenek@seznam.cz. 7. Department of Cardiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic. Electronic address: jiri.kettner@ikem.cz. 8. Department of Laboratory Methods, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic; Charles University, 3rd Faculty of Medicine, Ruská 87, 100 00 Prague 10, Czech Republic. Electronic address: anja@medicon.cz.
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 (99 th 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.
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 (99 th 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.
Authors: Maurits S Buiten; Mihály K de Bie; Joris I Rotmans; Friedo W Dekker; Marjolijn van Buren; Ton J Rabelink; Christa M Cobbaert; Martin J Schalij; Arnoud van der Laarse; J Wouter Jukema Journal: PLoS One Date: 2015-08-03 Impact factor: 3.240