PHOSPHATE (INORGANIC) VER.2

Additional Manufacturer Narrative

THE COBAS 4000 C311 STAND-ALONE SYSTEM SERIAL NUMBER WAS (B)(6). THE INVESTIGATION IS ONGOING.

Description of Event or Problem

THERE WAS AN ALLEGATION OF QUESTIONABLE PHOSPHATE (INORGANIC) VER.2 RESULTS FROM THE COBAS 4000 C311 STANDALONE SYSTEM. AN INTERFERENCE WAS SUSPECTED. THE INITIAL RESULT WAS 9.80 MG/DL WITH A DATA FLAG. SINCE THE VALUE WAS PARTICULARLY HIGH AND THERE WERE NO CLINICAL CONDITIONS COMPATIBLE WITH RENAL FAILURE OR SUCH A DEGREE OF HYPERPHOSPHATEMIA, THE TEST WAS REPEATED USING A NEW SAMPLE. THE ELEVATED VALUE WAS CONFIRMED AT 8.10 MG/DL WITH A DATA FLAG. THIS LED TO THE HYPOTHESIS OF INTERFERENCE AND THE COLLECTION OF A NEW SAMPLE. THE FOLLOWING MORNING (B)(6) 2025), A THIRD SAMPLE WAS TAKEN FROM THE PATIENT, YIELDING A RESULT OF 8.55 MG/DL WITH A DATA FLAG. THE SAMPLE WAS SENT TO A SECOND LABORATORY USING THE SAME METHOD ON A C311 ANALYZER. THE RESULT WAS 5.7 MG/DL. THE SAMPLE WAS ALSO TESTED IN ANOTHER LABORATORY, WITH A RESULT OF 3.40 MG/DL. AFTER PREVENTIVE MAINTENANCE WAS PERFORMED AND THE INSTRUMENT CHECKED, THE SAMPLES WERE REPEATED, AND THE RESULTS WERE THE SAME ELEVATED VALUES. NO SPECIFIC DATA WAS PROVIDED.