Unanticipated error in HbA(1c) measurement on the HLC-723 G7 analyzer

Clin Biochem. 2010 Apr;43(6):623-5. doi: 10.1016/j.clinbiochem.2009.12.020. Epub 2010 Jan 11.


Objectives: Investigation of falsely elevated HbA(1c) measurements on the HLC-723 G7 analyser.

Design and 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.

Conclusion: 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.

Publication types

  • Case Reports
  • Evaluation Study

MeSH terms

  • Automation
  • Blood Chemical Analysis / instrumentation*
  • Blood Chemical Analysis / methods
  • Blood Chemical Analysis / standards
  • Calibration
  • Chromatography, Ion Exchange / instrumentation
  • Chromatography, Ion Exchange / standards
  • Diabetes Mellitus / blood
  • Diabetes Mellitus / diagnosis*
  • Diagnostic Errors*
  • Glycated Hemoglobin A / analysis*
  • Hemolysis / physiology
  • Humans
  • Indicator Dilution Techniques
  • Reference Standards


  • Glycated Hemoglobin A
  • hemoglobin A1c protein, human