On (b)(6) 2022 the customer reported obtaining erroneously high psa (access hybritech psa prostate specific antigen (part number 37200, lot number 233605) results for one patient since 2016 and generated on customer's unicel dxi 800 access immunoassay analyzers (part number 973100 (b)(4)).The patient was diagnosed with prostate cancer in 2011 and had subsequent radical prostatectomy.In 2016 (exact date was not available), a reappearance of abnormal psa values (3.25 ng/ml) was observed on dxi analyzer (instrument serial number not specified), which fluctuated when reanalyzed.No further information was provided.In (b)(6) 2021, the patient was tested with a psa result of 64 ng/ml and in august the result was 90 ng/ml (dxi serial number not specified).The patient underwent a pet-ct scan (positron emission tomography - computerized tomography) as a result of the elevated access psa results without finding lesions suggestive of tumor disease.(b)(6) the study was extended and a f-psma (prostate-specific membrane antigen) pet was performed with the same result.Subsequently, 18f-fdg (fluoro- d-glucose) pet was performed, resulting in a negative result.No further information was provided.The date of event was selected to (b)(6) 2021 as last results before scans were obtained in (b)(6) 2021.In (b)(6) 2022, it was decided to measure total psa using two different methodologies.The access result was 3.43 ng/ml (dxi serial number not specified) and the abbott architect result was lower at 0.06 ng/ml.On (b)(6) 2022, the patient was retested with an access result of 14.42 ng/ml on the dxi (b)(4) while the roche methodology result was 0.04 ng/ml.No hardware errors or other assay issues were reported in conjunction with this event.The most recent calibration on dxi (b)(4) passed on (b)(6) 2022 with reagent lot 233605 and calibrator lot 125422.Qc was passing within the laboratory¿s established ranges.System checks passed on (b)(6) 2022 on both dxi.One patient sample was sent to the marseilles chu (complaint handling unit) for investigation.Sample used in (b)(6) 2022 is serum from a bd vacutainer sst tube.Sample volume was adequate, and processed from primary tube.Sample was centrifuged by the dxa 5000 and looked clear.The sample was processed the same day within approximately 2 hours.No further issues with sample integrity were reported by the customer.
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The full patient identifier is (b)(6).The customer did not provide patient demographics such patient date of birth, weight, ethnicity or race.The beckman psa reagent was not returned for evaluation.No hardware errors or other assay issues were reported in conjunction with this event.System performance indicators such as system check, calibration and quality control were passing within specifications at the time of the event.No other patient results were called into question.One patient sample from (b)(6) 2022 was sent to the marseilles chu (complaint handling unit) for investigation.Patient sample was first tested neat for the psa-hyb assay.Customer's result was confirmed.Then, a dilution testing was performed.Results did not show the presence of interferences since the test was linear.An interference testing, using different blockers, was then carried out.The blockers used in the interference testing consist of pool 1 (polymak 33 and hbr-1) and pool 2 (goat, mouse, rabbit, sheep and bovine iggs) which are composed of animal derived antibodies.Pool 3 (ap mutein, scavenger alp) was also tested.This interference testing demonstrated the presence of heterophile interfering substances since the addition of pool 1 and 2 of blockers significantly lowered the signal.Per the psa instructions for use (ifu), par number (pn) a85067 n, it states "for assays employing antibodies, the possibility exists for interference by heterophile antibodies in the patient sample.Patients who have been regularly exposed to animals or have received immunotherapy or diagnostic procedures utilizing immunoglobulins or immunoglobulin fragments may produce antibodies, e.G.Hama, that interfere with immunoassays.Additionally, other heterophile antibodies such as human anti-goat antibodies may be present in patient samples.Such interfering antibodies may cause erroneous results.Carefully evaluate the results of patients suspected of having these antibodies." in conclusion, the investigation demonstrated that heterophile interference, is the likely cause of the falsely elevated psa results obtained for this patient.There is no evidence to reasonably suggest that a malfunction occurred in conjunction with this event.
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