Response to “Increased Creatine Kinase MB and Cardiac Troponin T with Normal Cardiac Troponin I in Metastatic Alveolar Rhabdomyosarcoma”

[摘要] We wish to comment on the case reported recently by Isotalo et al. (1). Two different cardiac troponin I (cTnI) assays were used: the AxSYM (Abbott) and the Opus Plus (Dade Behring). The title of the letter claimed that the cTnI value was normal. This is not consistent with the data presented.The AxSYM values for cTnI of 1.2 (day 1), 0.8 (day 2), and 1.1 μg/L (2 weeks) are not normal. The limit of detection for the AxSYM is 0.3 μg/L, with a quoted upper reference limit of 0.4 μg/L and an acute myocardial infarction cutoff of 2.0 μg/L (2). The patient’s values fall within the range for detectable and prognostically significant myocardial damage.The main conclusion that Isotalo et al. (1) make is that the increased cardiac troponin T (cTnT) and creatine kinase MB (CK-MB) concentrations are the result of release from a non-cardiac source related to abnormal expression of these proteins. They did not perform experiments to detect evidence of abnormal cTnT or CK-MB expression in the tumor biopsy. Therefore, we fully agree with the authors that their conclusions were “speculative”. However, we disagree with their discussion. The authors clearly state that the patient had no biochemical evidence of renal failure. However, they go on to describe, in detail, the findings of three conflicting studies that discuss the issue of skeletal muscle expression of cTnT in uremic patients. The reference to these studies in this case presentation implies that the authors are making an association with the issues of cTnT in patients with renal failure. We believe this to be a tenuous link between their limited study and the subject of skeletal muscle expression of cTnT in renal failure. In addition, we feel that they have either misread or misinterpreted two of the references dealing with this … [↵][1]bAddress correspondence to this author at: Division of Biochemistry, Department of Laboratory Medicine, Ottawa Hospital–Civic Campus, 1053 Carling Ave., Ottawa, Ontario, Canada K1Y 4E9. Fax [phone]; e-mail jdonnelly{at}civich.ottawa.on.ca [1]: #xref-corresp-2-1

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