Variation in Hemoglobin A1c Linked to Hemoglobin S: Comparison of Analysis Results from ion Exchange Chromatography and an Immunoturbidimetric Method

Hemoglobin S can interfere with the measurement of glycated hemoglobin, an essential tool for diagnosing and monitoring diabetes. The objective of this study is to evaluate the analytical performance of 2 glycated haemoglobin assay methods.

A prospective cross-sectional study was conducted where 186 patients (61 homozygous sickle cell disease, 61 AA type subjects and 64 AS type subjects) were recruited. Glycated hemoglobin was measured by immunoturbidimetry method and ion exchange chromatography.

The coefficient of variation (CV) of the repeatability is 2.34% and 1.13% (normal rate) ; 2.32% and 1.65% (high rate) respectively for the immunoturbidimetric method and ion exchange chromatography. In reproducibility, the CV obtained are 3.23% and 2.64% (normal rate) and 3.27% and 2.22% (high rate), respectively for the immunoturbidimetric method and the ion exchange chromatography. Linearity is satisfactory for both methods. Mean glycated hemoglobin values ​​show no significant difference (the P-value is equal to 0.09, 0.17 and 0.70 respectively in subjects AA, AS and SS) in the 2 methods for patients with the same hemoglobin electrophoretic profile.

The analytical performances of the 2 methods are good but their use is not recommended in the biological diagnosis of diabetes and pre-diabetes due to interference from hemoglobin S, especially in the case of homozygous sickle cell disease or in the case of composite heterozygosity.