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The investigation determined that higher and lower than expected vitros intact pth (ipth) results have occurred with multiple patient samples when comparing data from a method comparison study between vitros ipth results and non-vitros roche and siemens systems.The assignable cause could not be determined.User error cannot be ruled out as contributing to the event.All the correlation samples were tested on a reagent pack with an expired on-board stability, and some of the correlation samples were also tested with an expired calibration.Since the quality control manufacturer and lot numbers are unknown, and since the customer provided no established control ranges, it is not possible to determine if the control results were acceptable and a reagent related performance issue cannot be ruled out as contributing to the event.However, the customer made no indication that quality control results were not acceptable.In addition, continual tracking and trending of complaints has not identified any signals that would point to a potential systemic issue with vitros ipth reagent lot 1870.No diagnostic within-run precision testing was performed that would assess the performance of the vitros 5600 integrated system, therefore, an instrument related performance issue cannot be ruled out as contributing to the event.The customer did not provide the collection dates for the samples, the dates the correlation samples were tested on the non-vitros roche and siemens systems, or the length of storage times and storage conditions between all three test events.It is unknown if the samples were tested initially on the vitros or non-vittros methods.The special precautions sections of the vitros ipth instructions for use states: "intact pth is labile and susceptible to fragmentation.Correct handling of patient samples is necessary to ensure that the pth molecule remains intact.The degree of fragmentation will depend on both time and temperature of storage." if the samples were initially tested with the vitros ipth method, and then retested using the non-vitros methods, it is possible that fragmentation of the ipth in the samples between test events caused the non-vitros results to be lower than the vitros results, however, this could not be confirmed.
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