ELECSYS ACTH

Description of Event or Problem

THERE WAS AN ALLEGATION OF QUESTIONABLE HIGH RESULTS FOR 1 PATIENT TESTED FOR ELECSYS ACTH (ACTH) ON A COBAS E 801 ANALYTICAL UNIT. THE ACTH RESULTS ARE ALLEGEDLY HIGH WITH NO KNOWN CAUSE, AS THE PATIENT IS ASYMPTOMATIC (PREVIOUSLY CUSHING'S DISEASE). THE INITIAL RESULT WAS 118,000 PG/ML. THE SAMPLE WAS REPEATED WITH VARIOUS DILUTIONS: X5: > 2000 PG/ML WITH A DATA FLAG, X10: >2000 PG/ML WITH A DATA FLAG, X20: >2000 PG/ML WITH A DATA FLAG, X40: >2000 PG/ML WITH A DATA FLAG, X75: 118,350 PG/ML, X100: 126,400 PG/ML. ON (B)(6) 2025, A NEW SAMPLE WAS OBTAINED, AND THE RESULT WAS APPROXIMATELY 25,000 PG/ML.

Additional Manufacturer Narrative

THE E801 ANALYZER SERIAL NUMBER WAS (B)(6). SAMPLE MATERIAL FROM THE PATIENT WAS RECEIVED FOR INVESTIGATION. THE CUSTOMER'S HIGH ACTH RESULTS WERE REPRODUCED AT THE INVESTIGATION SITE. SAMPLE MATERIAL FROM THE PATIENT WAS SENT TO AN EXTERNAL LABORATORY AND TESTED BY THE SIEMENS METHOD, WHERE THE ACTH WAS ALSO EXTREMELY HIGH (80,163 PG/ML). INTERFERENCE TESTING USING SIZE EXCLUSION CHROMATOGRAPHY (SEC) WAS PERFORMED. NO INTERFERENCE WAS FOUND. PEPTIDE MAPPING ANALYSIS OF THE SAMPLE FRACTIONS SUGGESTS THE HIGH ELECSYS ACTH RESULTS ARE CONSISTENT WITH AN ERRONEOUS DETECTION OF A DIFFERENT PEPTIDE FROM THE HIGHER-LEVEL PROOPIOMELANOCORTIN (POMC) PROTEIN.