Calibration signals were within the expected range.No quality control results for level 1 were provided.Quality control results of level 2 show fluctuations but all results were within the specified range for total psa.Upon review of the alarm trace, no relevant alarms were observed.The customer stores calibrators and controls in the freezer without temperature control.The customer thaws the aliquots, runs the quality control or calibrators, and freeze them again.The samples were requested but were not available for investigation.The investigation could not identify a product problem.The cause of the event could not be determined.The issue is consistent with an interference and/or a seldom psa isoform present in the sample that leads to the free psa values being greater than the total psa values.Per product labeling: "in rare cases, interference due to extremely high titers of antibodies to analytes specific antibodies, streptavidin or ruthenium can occur.These effects are minimized by suitable test design." "it is known that in rare cases psa isoforms do exist which may be measured differently by different psa tests.Findings of this kind have occasionally been reported for psa tests from various manufacturers.".
|