title: 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 (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.affiliation: 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.
authors.forename: Janka
authors.initials: J
authors.lastname: Franeková
authors.affiliation: Department of Cardiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic. Electronic address: martin.blaha@ikem.cz.
authors.forename: Martin
authors.initials: M
authors.lastname: Bláha
authors.affiliation: 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.
authors.forename: Jiří
authors.initials: J
authors.lastname: Bělohoubek
authors.affiliation: 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.
authors.forename: Markéta
authors.initials: M
authors.lastname: Kotrbatá
authors.affiliation: 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.
authors.forename: Peter
authors.initials: P
authors.lastname: Sečník
authors.affiliation: 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.
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Kubíček
authors.affiliation: Department of Cardiology, Institute for Clinical and Experimental Medicine, Vídeňská 1958/9, 140 21 Prague 4, Czech Republic. Electronic address: jiri.kettner@ikem.cz.
authors.forename: Jiří
authors.initials: J
authors.lastname: Kettner
authors.affiliation: 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.
authors.forename: Antonín
authors.initials: A
authors.lastname: Jabor
mesh_terms: D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D001416:Back Pain / Q000097:blood / Q000150:complications / Q000473:pathology; D002037:Bundle-Branch Block / Q000097:blood / Q000150:complications / Q000473:pathology; D002637:Chest Pain / Q000097:blood* / Q000150:complications / Q000473:pathology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000150:complications / Q000473:pathology; D050171:Dyslipidemias / Q000097:blood / Q000150:complications / Q000473:pathology; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000150:complications / Q000473:pathology; D007118:Immunoassay; D007075:Immunoglobulin M / Q000097:blood*; D051379:Mice; D010024:Osteoporosis / Q000097:blood / Q000150:complications / Q000473:pathology; D012016:Reference Values; D019210:Troponin I / Q000097:blood*; D020107:Troponin T / Q000097:blood*
chemical_list: D000911:Antibodies, Monoclonal; D007075:Immunoglobulin M; D019210:Troponin I; D020107:Troponin T
keywords: Heterophile antibodies; Immunoassay interference; Troponin