Unanticipated error in HbA(1c) measurement on the HLC-723 G7 analyzer.
OBJECTIVE
Investigation of falsely elevated HbA(1c) measurements on the HLC-723 G7 analyser.


METHODS
Comparison of HbA(1c) in blood samples that were diluted either in hemolysis reagent or water.


RESULTS
HbA(1c) results became falsely elevated when samples were diluted in hemolysis reagent, but not in water. QC-procedures failed to detect this error as calibrator and QC samples were manually diluted in water, according to manufacturer's instructions, whereas patient samples were automatically diluted using hemolysing reagent. After replacement of the instruments' sample-loop and rotor seal comparable HbA(1c) results were obtained, irrespective of dilution with hemolysing reagent or water.


CONCLUSIONS
This case illustrates the importance of treating calibrator and QC materials similar to routine patient samples in order to prevent unnoticed drift in patient HbA(1c) results.
van den Ouweland
Johannes M W
JM
Department of Clinical Chemistry, Canisius Wilhelmina Hospital, Weg door Jonkerbos 100, 6532 SZ Nijmegen, The Netherlands. j.v.d.ouweland@cwz.nl
de Keijzer
Marinus H
MH
van Daal
Henny
H
D001331:Automation; D001774:Blood Chemical Analysis / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D002138:Calibration; D002852:Chromatography, Ion Exchange / Q000295:instrumentation / Q000592:standards; D003920:Diabetes Mellitus / Q000097:blood / Q000175:diagnosis*; D003951:Diagnostic Errors; D006442:Glycated Hemoglobin / Q000032:analysis*; D006461:Hemolysis / Q000502:physiology; D006801:Humans; D007201:Indicator Dilution Techniques; D012015:Reference Standards
D006442:Glycated Hemoglobin; C517652:hemoglobin A1c protein, human