N ANTISERA TO HUMAN IMMUNOGLOBULINS (IGG)

Additional Manufacturer Narrative

ANALYSIS OF THE INSTRUMENT AND INSTRUMENT DATA INDICATE THAT THE CAUSE FOR THE DISCORDANT LOW CSF IGG RESULT WAS ANTIGEN EXCESS. THE ISSUE WAS RESOLVED BY REPEATING THE SAMPLE AT A HIGHER DILUTION AS DESCRIBED IN THE REAGENT INSTRUCTIONS FOR USE. THE N ANTISERUM TO HUMAN IGG INSTRUCTIONS FOR USE DESCRIBES THE SCENARIO IN THE LIMITATIONS OF PROCEDURE SECTION. THE IMMUNOGLOBULIN ASSAYS HAVE BEEN DESIGNED TO MINIMIZE ANTIGEN EXCESS IN THE INITIAL SAMPLE DILUTIONS. HOWEVER, IT CANNOT BE COMPLETELY ELIMINATED AND IN RARE CASES VERY HIGH IMMUNOGLOBULIN CONCENTRATIONS MAY PRODUCE FALSELY-LOW RESULTS. ESPECIALLY MONOCLONAL IMMUNOGLOBULINS MAY SHOW REACTIVITY DIFFERENT FROM THE POLYCLONAL STANDARD, WHICH IN ISOLATED CASES MAY LEAD TO ARTIFICIALLY DECREASED OR NON-LINEAR RESULTS. IN CASE OF SERUM OR PLASMA DETERMINATIONS, THE CONSTELLATION OF IGG, IGA AND IGM SHOULD BE ASSESSED. A CHECK OF IGG RESULTS IN CSF SHOULD BE PERFORMED BY MEANS OF RATIO DIAGRAMS. IN CASE OF QUESTIONABLE RESULTS, THE DETERMINATIONS SHOULD BE REPEATED USING THE NEXT HIGHER SAMPLE DILUTION. THE INSTRUMENT IS PERFORMING WITHIN SPECIFICATIONS. NO FURTHER EVALUATION OF THE DEVICE IS REQUIRED.

Description of Event or Problem

A DISCORDANT LOW IGG RESULT WAS OBTAINED ON A PATIENT SPINAL FLUID (CSF) SAMPLE ON THE BN PROSPEC INSTRUMENT. THE PATIENT RESULT WAS NOT REPORTED TO THE PHYSICIAN. THE LABORATORY REPEATED THE SAME SAMPLE AT A HIGHER DILUTION AND A HIGHER RESULT WAS OBTAINED AND REPORTED. PATIENT TREATMENT WAS NOT ALTERED OR PRESCRIBED BASED ON THE INITIAL DISCORDANT LOW CSF IGG RESULT. THERE IS NO INDICATION OF ANY ADVERSE HEALTH CONSEQUENCES DUE TO THE INITIAL DISCORDANT LOW CSF IGG RESULT.