The customer observed a reproducibly elevated immulite 2000 xpi br-ma (ca15-3) result on a patient compared to a lower alternate ca15-3 test method which was in accordance with the patient clinical history.Quality control (qc) was within range and no other samples were affected indicating this is a sample/patient specific incident.The immulite 2000 ca15-3 assay has no claim for method comparison to the alternate ca15-3 test method.Ca15-3 antigen levels in a given specimen determined with assays from different manufacturers can vary due to differences in assay methods and reagent specificity.Values obtained with different assays cannot be used interchangeably.The potential cause of the elevated ca15-3 result is unknown; however, siemens cannot rule out an interferent in the sample causing the elevated result.Heterophilic antibodies in human serum can react with the immunoglobulins included in the assay components causing interference with in vitro immunoassays.Immunoassays are subject to a number of interferences including those caused by endogenous antibodies.Interference can occur because of heterophile antibodies, anti-animal antibodies and auto antibodies.Patients exposed to animals or animal serum products can be prone to this interference and anomalous values may be observed.The interfering antibodies can give rise to a falsely high result.The erroneous result is recognized as being inconsistent with the patient's clinical picture.The potential interferent may not necessarily be due to an interfering antibody but may be due to other exogenous interferences such as drugs, nutritional supplements and/or herbal medicine in the blood.Typical laboratory strategies to resolve potential sample interferents would be treatment with a heterophile binding tube (hbt) and/or serial dilution of the sample to attempt to dilute out the interfering substance if one is present.Based on the available information, no potential product problem exists.The customer is operational.The limitations section of the instructions for use states the following: "for diagnostic purposes, the results obtained from this assay should always be used in combination with the clinical examination, patient medical history, and other findings." the assay is performing within specification.No further evaluation of the device is required.
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The customer observed a discordant, elevated result on a patient sample using the immulite 2000 xpi br-ma (ca15-3) assay and questioned by the physician(s).The same sample when repeated was elevated.The same sample was repeated on an alternate ca15-3 test method, resulting lower.The lower ca15-3 result agreed with the patient's clinical picture and was reported to the physician(s) as the correct result.There are no known reports that treatment was altered or prescribed or adverse health consequences due to the discordant br-ma (ca15-3) result.
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