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

Additional Manufacturer Narrative

(B)(4). THIS EVENT OCCURRED IN (B)(6).

Description of Event or Problem

THE CUSTOMER RECEIVED QUESTIONABLE ELECSYS PROBNP II IMMUNOASSAY RESULTS FOR ONE PATIENT FROM A 6000 E 601 MODULE. THE SERIAL NUMBER WAS REQUESTED BUT WAS NOT PROVIDED. THE PATIENT SAMPLE REPEATEDLY HAD A RESULT OF <0.6 PMOL/L WITH A DATA FLAG AND THE RESULT WAS REPORTED OUTSIDE THE LABORATORY. THE TREATING PHYSICIAN QUESTIONED IF IT IS PLAUSIBLE TO HAVE THIS RESULT FOR A PATIENT. THERE WAS NO ALLEGATION OF AN ADVERSE EVENT. THE PATIENT WAS NOT KNOWN TO HAVE THE CLINICAL SYMPTOMS RELATED TO HEART FAILURE. THE PATIENT HAS BEEN INVESTIGATED FOR LUNG FUNCTION (A-TYPCIAL THORAX COMPLAINTS), HAS NORMAL GLUCOSE VALUES, AND A CHOLESTEROL VALUE OF 5 (NO UNIT OF MEASURE PROVIDED). NO PREVIOUS PRO-BNP OR TROPONIN RESULTS WERE KNOWN FOR THE PATIENT. THE PATIENT HAS A FAMILY HISTORY OF HEART FAILURE AND THE PATIENT FEARS HE WILL HAVE HEART FAILURE AS WELL. THE FATHER OF THE PATIENT DIED FROM HEART FAILURE AND THE BROTHER OF THE PATIENT HAD A NON-LETHAL HEART ATTACK. INTERFERENCE OR AN NT-PROBNP GENETIC VARIANT WAS SUSPECTED FOR THE PATIENT. SAMPLE FROM THE PATIENT WAS SUBMITTED FOR INVESTIGATION.

Additional Manufacturer Narrative

A SPECIFIC ROOT CAUSE COULD NOT BE DETERMINED. SAMPLE FROM THE PATIENT WAS SUBMITTED FOR INVESTIGATION AND THE CUSTOMER¿S LOW RESULT WAS CONFIRMED. FURTHER TESTING OF THE PATIENT SAMPLE FOUND IT DID NOT CONTAIN THE GENETIC MUTATIONS (R72H AND E69D). THE SAMPLE WAS THEN TESTED WITH THE GEN 1 PROBNP ASSAY WHICH USES A POLYCLONAL ANTIBODY INSTEAD OF THE MONOCLONAL ANTIBODY USED IN THE GEN 2 ASSAY. THE RESULT WAS NEGATIVE FOR PROBNP. THE RESULTS AFTER THE SAMPLE WAS TREATED WITH HETEROPHILIC BLOCKING TUBES (HBT) INDICATED NO INTERFERENCE WITH IGM. FURTHER TESTING SHOWED THAT AN INTERFERENCE WITH RUTHENIUM WAS VERY UNLIKELY. THE SAMPLE WAS THEN TESTED FOR PROBNP ON A SIEMENS IMMULITE AND THE RESULT WAS 172 NG/L AND WAS CLEARLY ABOVE THE CUT OFF VALUE. FURTHER CLARIFICATION OF THE DISCREPANCY WAS NOT POSSIBLE WITH THE AVAILABLE METHODS AND THE CURRENT STATE OF THE ART.