ELECSYS VITAMIN B12 II

Additional Manufacturer Narrative

QUALITY CONTROL RESULTS WERE IN THE ACCEPTABLE RANGE. VITAMIN SUPPLEMENTATION WAS RULED OUT. SAMPLE FROM THE PATIENT WAS SUBMITTED FOR INVESTIGATION.

Description of Event or Problem

THERE WAS AN ALLEGATION OF QUESTIONABLE ELECSYS VITAMIN B12 IMMUNOASSAY RESULTS FROM COBAS 6000 E 601 MODULE SERIAL NUMBER (B)(4). THE INITIAL RESULT WAS >2000 PG/ML. WHEN DILUTED 1/2 MANUALLY, THE RESULT WAS 2376 PG/ML. THE HIGH RESULT WAS REPORTED OUTSIDE OF THE LABORATORY AND THE PHYSICIANS BELIEVED THE HIGH RESULTS (>2000 PG/ML) MAY BE DUE TO INTERFERENCE. THE PRESENCE OF IMMUNOGLOBULIN-VITAMIN B12 COMPLEXES (MACRO-B12) WAS SUSPECTED. THE SAMPLE WAS PROCESSED AGAIN WITH A DILUTION WITH PEG (1:1), OBTAINING A RECOVERY OF 17% (398 PG/ML) COMPARED TO A CONTROL SAMPLE WITH B12 ALSO ELEVATED WHICH RECOVERED 80%.

Additional Manufacturer Narrative

THE SAMPLE WAS INVESTIGATED WITH SIZE EXCLUSION CHROMATOGRAPHY (SEC) AND SHOWED MORE OF AN ATYPICAL DISTRIBUTION OF VITAMIN B12 BOUND TO BINDING PROTEINS. THIS IS CONSISTENT WITH AN IGG INTERFERENCE (MACROB12) IN ADDITION TO HIGH FREE VITAMIN B12 AND HOLOTC CONCENTRATIONS. THIS INTERFERENCE IS DOCUMENTED IN PRODUCT LABELING FOR THE ASSAY: NOTE: THE PRESENCE OF IMMUNOGLOBULIN-VITAMIN B12 COMPLEXES MAY CAUSE UNEXPECTEDLY HIGH VALUES OF VITAMIN B12. BASED ON THE AVAILABLE DATA, NO PRODUCT PROBLEM COULD BE FOUND. SECTION D4, EXPIRATION DATE WAS UPDATED.