The initial reporter stated they received questionable results for one patient sample tested with the elecsys tsh ver.2 assay, ft4, ft3, elecsys cortisol ii, elecsys testosterone ii assay, and elecsys dhea-s on a cobas e 411 immunoassay analyzer.The results measured on the e411 analyzer did not compare to results obtained with competitor methods.The results from the e411 analyzer were reported outside of the laboratory.The specific ft3 and ft4 assays used are unknown.This medwatch will apply to the testosterone assay.Please refer to the medwatch with patient identifier (b)(6) for information related to the tsh assay.Please refer to the medwatch with patient identifier (b)(6) for information related to the ft4 assay.Please refer to the medwatch with patient identifier (b)(6) for information related to the ft3 assay.Please refer to the medwatch with patient identifier (b)(6) for information related to the cortisol assay.Please refer to the medwatch with patient identifier (b)(6) for information related to the dhea-s assay.The sample was initially tested on the customer's e411 analyzer.The sample was then sent to a second site, where it was tested on a beckman coulter instrument and discrepancies were observed.The sample was treated with a heterophilic blocking tube and ft3 and ft4 testing was repeated on the beckman analyzer with no improvement in recovery.The sample was repeated again on the siemens atellica and abbott architect platforms.The reporter stated that the patient was recently tested again on the e411 analyzer and the same pattern was found.The serial number of the e411 analyzer is (b)(4).
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Further investigations of the sample determined that it contains an interfering factor against the streptavidin component of the assay.Immunoglobulin concentrations were measured in the sample and a highly elevated concentration of igm could be determined, which leads to further unspecific interference in the assay.These interferents would affect recovery of all elecsys assays.Per product labeling: "in rare cases, interference due to extremely high titers of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur.These effects are minimized by suitable test design.".
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