Effects of Hemoglobin C and S Traits on Glycohemoglobin Measurements by Eleven Methods

Abstract

Patients with diabetes mellitus routinely have glycohemoglobin (GHb) testing performed to monitor glycemic control and assess risk for developing complications of their disease (1 ). The accuracy of several GHb methods can be adversely affected by the presence of hemoglobin (Hb) C or S trait (2-6 ). It has been estimated that there are at least 200 000 Americans with diabetes mellitus who also have either Hb C or S trait (6 ). We have recently shown that the presence of Hb C or S trait does not affect the accuracy of GHb measurements made by the CLC 330 boronate affinity HPLC method (7 ). We therefore evaluated the effects of Hb C and S traits on 11 commercial GHb methods, using the CLC 330 assay as the comparison method.Whole blood samples from individuals homozygous for Hb A (n ϭ 73) and heterozygous for Hb C or S (n ϭ 46 and 76, respectively) were collected in EDTA-containing tubes. After routine clinical testing had been completed, Hb variants were identified by inspection of chromatograms obtained with a VARIANT analyzer (Bio-Rad Laboratories) and the Beta Thal Short program run according to the manufacturer's instructions. Aliquots of these samples that had 4 -14% Hb A 1c were stored at 2-8°C and analyzed within 10 days of collection except for aliquots for the HA8160 and HA8160 Beta Thal (BT) methods, which were shipped on dry ice and stored frozen until analysis. Not all samples were analyzed by each analytic method. This study was approved by the Institutional Review Board of the University of Utah.Samples were analyzed by the following instruments/ methods: A1c 2.2 Plus and G7 (Tosoh); A1cNow (Metrika); D-10, DiaSTAT, and VARIANT II (Bio-Rad Laboratories); Dimension RxL (Dade Behring); HA8160 HbA1c and HA8160 BT (Menarini Diagnostics); and PDQ (Primus). All of these methods were used according to the manufacturers' instructions and have been certified by the National Glycohemoglobin Standardization Program (NGSP). The CLC 330 GHb analyzer (Primus) was used as the comparison method in an NGSP Network Laboratory with in-house calibrator materials and assigned values. Results for all methods are reported as NGSP Hb A 1c equivalents.For each test method, results obtained for each type of sample (homozygous Hb A, heterozygous Hb C, and heterozygous Hb S) were compared with those obtained by the CLC 330 comparison method. An overall test of coincidence of two least-squares linear regression lines was performed with SAS software (SAS Institute) to determine whether the presence of Hb C or S trait caused a statistically significant difference (P Ͻ0.01) in results relative to the comparison method. Deming regression analysis was performed to determine whether the presence of Hb C or S trait produced a clinically significant effect on GHb results. Given recommendations by the American Diabetes Association of an upper reference limit of 6% and an action limit of 8%, we chose Hb A 1c evaluation limits of 6% and 9%. After correcting for possible calibration bias by comparing results from the homozygous Hb A sample ...

New screening technologies for type 2 diabetes mellitus appropriate for use in tuberculosis patients [Review article]

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Comparison of glycated hempglobin with HPLC and capillary electrophoresis

“…Considering these facts Sebia Capillary Flex Piercing II proves to have superior performance in presence of additional hemoglobin fractions. [11][12][13][14][15] The linearity for Sebia Flex Piercing II is upto 16.4% and limit of detection is 4.6% (Kit Insert) which slightly lower than Biorad D10 for which the linearity is upto 18.5% as well as limit of detection is 3.8%. (Kit Insert) The run time for individual sample in Sebia Flex Piercing II is 9 minute whereas in Biorad D10 is 3 min.…”

Lack of precision in HbA1c values on variant II in cases of hemoglobin Q India

“…According to the Hemoglobin A1c program pack insert hemoglobin heterozygous variants S and C, have no clinically significant effect on the A1c values because the retention time of hemoglobins S and C are longer than HbA and the peak areas of hemoglobin S and C are not included in the calculation of total hemoglobin (10,11). But, other abnormal hemoglobin variants have not been fully evaluated on the Variant II TM hemoglobin A1c program.…”

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