Sample transport and/or storage can cause falsely low HbA1c levels in blood cells measured by enzymatic assay
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Although HbA1c measurement by enzymatic assay (EA-HbA1c) is widely used in health-screening settings in Japan, recent studies have suggested lower EA-HbA1c levels as compared with HbA1c levels measured by high-performance liquid chromatography (HPLC-HbA1c). Hypothesizing that falsely low levels of EA-HbA1c are attributable to hemolysis caused by sample transport and/or storage, we measured EA-HbA1c in blood cells and whole blood after sample transport and compared them with HPLC-HbA1c levels. Blood samples were collected from ten non-diabetic individuals into sodium fluoride-containing blood collection tubes and immediately measured for EA-HbA1c in blood cells. After transport, the blood samples were again subjected to measurement of EA-HbA1c levels in blood cells and whole blood the following day. These EA-HbA1c levels were compared with HPLC-HbA1c levels. EA-HbA1c levels in blood cells measured immediately after sample collection did not significantly differ from HPLC-HbA1c levels. Transported blood samples showed hemolysis and significantly lower EA-HbA1c levels in blood cells, as compared with HPLC-HbA1c levels, whereas no significant difference was observed between EA-HbA1c levels in whole blood and HPLC-HbA1c levels. Transported blood samples showed hemolysis and falsely low EA-HbA1c levels in blood cells. Hemolysis caused by sample transport and/or storage might be responsible for the falsely low EA-HbA1c levels. This should be kept in mind, because falsely low HbA1c levels may lead to a false-negative diagnosis of diabetes.
KeywordsHbA1c Hemolysis Sodium fluoride Enzymatic assay
The authors would like to acknowledge the Arkray Inc. for their assistance in performing HbA1c measurements in this study.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Human rights and informed consent
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions. Informed consent or a substitute for it was obtained from all patients prior to their participation in this study.
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