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The investigation determined the customer reported that higher than expected vitros crea results were obtained from a single patient sample tested on a vitros 5600 integrated system.The most likely assignable cause for the issue is an unknown sample interferent.Per the vitros crea instructions for use (ifu), limitations of the procedure, known interferences: creatine: at a creatinine concentration of 1.5 mg/dl (133 umol/l), creatine greater than 8 mg/dl (707 umol/l) will be flagged with a dp code (because highly elevated creatine concentrations may cause excessive background density).At a creatinine concentration of 14 mg/dl (1237 umol/l), creatine greater than 1 mg/dl (88 umol/l) will be flagged with a dp code.Refer to sample dilution for dilution instructions.The vitros 5600 integrated system did not generate a vitros crea result when the patient sample was tested undiluted due to the occurrence of a dp sample code, which indicates substrate depletion.The most likely cause of the dp sample code is an interferent in the sample, such a creatine, which would be diluted out with the sample dilution prior to repeat testing.Per the vitros flags and codes on reports, the description for a dp sample code is substrate depletion, and the suggested action is to dilute the sample and repeat the test.The higher-than-expected vitros crea results were obtained from 2x dilutions of the sample.The historical quality control data review indicates the vitros crea slides did not likely contribute to the event, as the quality control results were acceptable during the timeframe of the event.In addition, continual tracking and trending did not indicate a performance issue with vitros crea slide lot 1515-3568-9586.The customer made no indication that there was a performance issue with the vitros 5600 integrated system.Historical quality control results indicated vitros crea slide lot 1515-3568- 9586 was performing as intended on the vitros 5600 integrated system.However, since no diagnostic within-run precision testing was performed to assess the performance of the vitros 5600 system, an instrument performance issue cannot be entirely ruled out as contributing to the event.Improper patient sample handling did not likely contribute to the event as the higher-than-expected vitros crea results were isolated to the affected sample, and the results were reproducible.
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