The accuracy of Glycosylated Hemoglobin a Index Measurement in Medical Laboratories in Isfahan City

Today, Glycosylated hemoglobin A (HbA1c) is used as a diagnostic criterion for diabetes and long-term monitoring of plasma glucose level. Therefore, it is essential that HbA1c be measured accurately. The aim of this study was to investigate the common HbA1c index measurement methods in laboratories in Isfahan and compare the accuracy of their results with the reference method.

In this cross-sectional study, three blood sample of a volunteer had been sent to 37 laboratories. Among them, two laboratories measured this parameter by HPLC method and were considered as a reference. For each laboratory, the coefficient of variation (CV) was calculated. One-way ANOVA and Bonferroni post hoc test were used to compare the results of different methods of measuring HbA1c with the reference method.

Comparison of the laboratories results with the reference method showed that 60% of the laboratories reported the percent of HbA1c index beyond the permitted range with an unfavorable report. The mean and standard deviation and CV index range were 2.8 and 4.4, (from 0.65 to 25.18%), respectively. Comparison of the different methods results with the reference method showed that capillary electrophoresis and immunoturbidometry and enzymatics had good accuracy. The highest accuracy was related to capillary electrophoresis. The methods with the lowest measurement accuracy were nephelometry and column chromatography, respectively.

Despite the standardization of methods for measuring HbA1c, it was noted that different results of the same blood sample was reported. In addition to the High Performance Liquid Chromatography method, the capillary electrophoresis seems to provide a more acceptable result than other methods.