PROBNP II, N-TERMINAL PRO B-TYPE NATRIURETIC PEPTIDE

Additional Manufacturer Narrative

(B)(4). THE EVENT OCCURRED IN: (B)(6).

Description of Event or Problem

THE CUSTOMER COMPLAINED OF A FALSE NEGATIVE RESULT FOR 1 PATIENT TESTED FOR ELECSYS PROBNP II IMMUNOASSAY (PROBNP II) IN COMPARISON TO THE CREATININE RESULT. THE INITIAL PROBNP II RESULT WAS < 5 PG/ML. THE SAMPLE WAS REPEATED TWICE WITH RESULTS OF < 5 PG/ML AND < 5 PG/ML. THE RESULT OF < 5 PG/ML WAS RELEASED OUTSIDE OF THE LABORATORY, BUT WAS NOT BELIEVED TO BE CORRECT SINCE THE PATIENT HAD A CREATININE RESULT OF 2.5 MG/DL. THERE WAS NO ALLEGATION OF AN ADVERSE EVENT. THE CUSTOMER USED COBAS 6000 E 601 MODULE SERIAL NUMBER (B)(4). THE INVESTIGATION IS CURRENTLY ONGOING.

Additional Manufacturer Narrative

THE SAMPLE WAS RE-MEASURED FOR FURTHER INVESTIGATION AND THE CUSTOMER¿S RESULT OF A PROBNP II VALUE OF < 5 PG/ML WAS REPRODUCED. TWO POINT MUTATIONS (R72H AND E69D) IN THE EPITOPE OF THE DETECTION ANTIBODY WAS SUSPECTED. TESTING WITH THE PROBNP II REAGENT SUPPLEMENTED WITH ADDITIONAL DETECTION ANTIBODIES FOR THESE MUTATIONS SHOWED THAT THE BNP IN THE SAMPLE CONTAINED THE R72H MUTATION. THEREFORE, IT IS NOT DETECTED BY THE ELECSYS PROBNP II IMMUNOASSAY. THE PATIENT SAMPLE WAS FOUND TO HAVE A TYPE OF POINT MUTATION THAT IS EXTREMELY RARE AND SO FAR HAS ONLY BEEN FOUND IN SAMPLES FROM JAPAN. A DISCLAIMER WAS ADDED TO PRODUCT LABELING.

Additional Manufacturer Narrative

THE SAMPLE WAS RECEIVED FOR FURTHER INVESTIGATION AND THE CUSTOMER'S RESULTS WERE REPRODUCED. THE INVESTIGATION IS CURRENTLY ONGOING.