DIMENSION

Additional Manufacturer Narrative

SIEMENS FILED THE INITIAL MDR 2517506-2026-00066 ON 08-APR-2026. ADDITIONAL INFORMATION (20-APR-2026): SIEMENS HEALTHCARE DIAGNOSTICS HAS CONCLUDED THE INVESTIGATION OF THE EVENT. SIEMENS EVALUATED THE INSTRUMENT DATA AND THE INFORMATION PROVIDED BY THE CUSTOMER AND FOUND THAT THE PHOTOMETRIC PERFORMANCE WAS STABLE AND CONSISTENT OPTICAL MEASUREMENTS, WITH NO EVIDENCE OF ABNORMAL REACTION CURVES, OPTICAL NOISE, OR CUVETTE-RELATED PHOTOMETER INSTABILITY. THE QUALITY CONTROL (QC) PERFORMED AFTER THE EVENT RECOVERED WITHIN ACCEPTABLE RANGE, INDICATING THAT THE ASSAY PERFORMANCE WAS STABLE, THE INSTRUMENT OPTICS, REAGENT DELIVERY, AND CALIBRATION STABILITY ARE CONSIDERED VERIFIED, AND THE RAW PHOTOMETRIC FILTER VALUES DEMONSTRATE CONSISTENT REACTION PROGRESSION WITHOUT ANALYTICAL DRIFT INDICATING THAT THE SYSTEM WAS FUNCTIONING WITHIN EXPECTED PERFORMANCE SPECIFICATIONS. TACROLIMUS (TAC) ASSAY UTILIZES A HOMOGENEOUS MAGNETIC SEPARATION (HM) PROCESS FOLLOWED BY PHOTOMETRIC MEASUREMENT, WHERE THE FINAL CALCULATED RESULT DEPENDS ON EFFICIENT RED BLOOD CELL LYSIS, ADEQUATE WHOLE-BLOOD MIXING, AND HOMOGENEOUS SAMPLE TRANSFER BEFORE PHOTOMETRIC MEASUREMENT. THE TROUBLESHOOTING AND METHOD GUIDANCE INDICATE THAT WHOLE-BLOOD TAC TESTING IS PARTICULARLY SENSITIVE TO SAMPLE PREPARATION VARIABLES, INCLUDING INCOMPLETE RED BLOOD CELLS (RBC) RESUSPENSION, DELAYED MIXING AFTER ALIQUOTING, ETHYLENEDIAMINETETRAACETIC ACID (EDTA) CONCENTRATION VARIATION, OR MICRO-CLOT/PARTICULATE PRESENCE IN WHOLE BLOOD SAMPLES. SIEMENS OBSERVED REPEAT VARIABILITY AND IS MOST CONSISTENT WITH SAMPLE-RELATED VARIABILITY INHERENT TO WHOLE-BLOOD TESTING, SUCH AS INCOMPLETE SAMPLE RESUSPENSION, OR MINOR PRE-ANALYTICAL FACTORS THAT MAY INFLUENCE ANALYTE RECOVERY BETWEEN REPEAT ASPIRATES. SMALL VARIATIONS IN WHOLE BLOOD RESUSPENSION OR SAMPLE SETTLING MAY RESULT IN REPEAT VARIABILITY, PARTICULARLY WHEN ANALYTE CONCENTRATIONS FALL WITHIN THE THERAPEUTIC RANGE. SUCH VARIABILITY CAN OCCUR EVEN WHEN QC MATERIALS PERFORM WITHIN RANGE, AS QC MATRICES DIFFER FROM NATIVE WHOLE BLOOD SAMPLES. BASED ON THE AVAILABLE INFORMATION, SIEMENS DETERMINED THAT THE ERRONEOUSLY ELEVATED (TAC) RESULT IS CONSISTENT WITH SAMPLE-RELATED FACTORS INHERENT TO WHOLE BLOOD TACROLIMUS TESTING, SUCH AS VARIABILITY IN SAMPLE HOMOGENIZATION OR SETTLING PRIOR TO ASPIRATION, WHICH MAY AFFECT ANALYTE DISTRIBUTION. THE DEVICE IS PERFORMING ACCORDING TO SPECIFICATIONS. NO FURTHER EVALUATION IS REQUIRED. NOTE: IN SECTION H6, THE CODES FOR INVESTIGATION FINDINGS AND INVESTIGATION CONCLUSIONS HAVE BEEN UPDATED TO REFLECT THE ADDITIONAL INFORMATION.

Additional Manufacturer Narrative

A UNITED STATES (US) CUSTOMER CONTACTED THE SIEMENS HEALTHCARE DIAGNOSTICS REMOTE SERVICES CENTER (RSC) REGARDING AN ERRONEOUSLY ELEVATED TACROLIMUS (TAC) RESULT OBTAINED ON A PATIENT SAMPLE ON A DIMENSION EXL 200 INTEGRATED CHEMISTRY SYSTEM. QUALITY CONTROL (QC) RECOVERED ACCEPTABLY ON THE EVENT DATE. SIEMENS IS EVALUATING THE EVENT.

Description of Event or Problem

THE CUSTOMER REPORTED THAT THEY OBTAINED AN ERRONEOUSLY ELEVATED TACROLIMUS (TAC) RESULT ON A PATIENT SAMPLE ON A DIMENSION EXL 200 INTEGRATED CHEMISTRY SYSTEM. THE SAMPLE WAS PROCESSED THREE TIMES ON THE SAME DIMENSION EXL 200 INTEGRATED CHEMISTRY SYSTEM. THE INITIAL RESULT AND THE 2ND REPEAT RESULT WERE CONSISTENT, CONSIDERED CORRECT, AND REPORTED TO THE PHYSICIAN(S). THE 1ST REPEAT RESULT WAS ELEVATED AND CONSIDERED ERRONEOUS. THE ERRONEOUS RESULT WAS NOT REPORTED TO THE PHYSICIAN(S). THERE ARE NO KNOWN REPORTS OF PATIENT INTERVENTION OR ADVERSE HEALTH CONSEQUENCES DUE TO THE ERRONEOUSLY ELEVATED TAC RESULT.