Effects of Hemoglobin (Hb) E and HbD Traits on Measurements of Glycated Hb (HbA1c) by 23 Methods

Abstract

Background: Glycohemoglobin (GHB), reported as hemoglobin (Hb) A1c, is a marker of long-term glycemic control in patients with diabetes and is directly related to risk for diabetic complications. HbE and HbD are the second and fourth most common Hb variants worldwide. We investigated the accuracy of HbA1c measurement in the presence of HbE and/or HbD traits. Methods: We evaluated 23 HbA1c methods; 9 were immunoassay methods, 10 were ion-exchange HPLC methods, and 4 were capillary electrophoresis, affinity chromatography, or enzymatic methods. An overall test of coincidence of 2 least-squares linear regression lines was performed to determine whether the presence of HbE or HbD traits caused a statistically significant difference from HbAA results relative to the boronate affinity HPLC comparative method. Deming regression analysis was performed to determine whether the presence of these traits produced a clinically significant effect on HbA1c results with the use of ±10% relative bias at 6% and 9% HbA1c as evaluation limits. Results: Statistically significant differences were found in more than half of the methods tested. Only 22% and 13% showed clinically significant interference for HbE and HbD traits, respectively. Conclusions: Some current HbA1c methods show clinically significant interferences with samples containing HbE or HbD traits. To avoid reporting of inaccurate results, ion-exchange chromatograms must be carefully examined to identify possible interference from these Hb variants. For some methods, manufacturers’ instructions do not provide adequate information for making correct decisions about reporting results.

Current controversies in the use of haemoglobin A1c

“…An international consensus committee has recommended that results should be reported worldwide in both SI units (mmol ⁄ mol) and derived NGSP ⁄ DCCT units (%) [38]. Acknowledging the limitations of the ADAG study, the consensus committee decided against the routine HbC [92] HbE [93] HbD [93] Hereditary persistence of HbF [94] Chemical derivatives of haemoglobin Carbamylated haemoglobin (e.g. as a result of uraemia) [95] Acetylated haemoglobin (e.g.…”

Status of Hemoglobin A1c Measurement and Goals for Improvement: From Chaos to Order for Improving Diabetes Care

“…Several reports have included analysis of the effects of these hemoglobins on Hb A 1c results (31)(32)(33)(34). The findings are summarized on the NGSP Web site (48 ).…”

Characterization of a Double Heterozygote HbE/β+ Thalassemia IVS 1-1 [G>T] in a Juvenile Diabetic

“…Little et al [6] showed that most HPLCs gave artificially low HbA1c results when compared to affinity chromatography. No clinically significant difference was found for HbA1c results measured with immunoassay.…”