Analysis of glycated hemoglobin A1c by capillary electrophoresis and capillary isoelectric focusing (original) (raw)
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A comparative evaluation of glycosylated haemoglobin assays: feasibility of references and standards
Diabetologia, 1984
Four assays; high pressure liquid chromatography, colorimetric with thiobarbituric acid, affinity columns, and microcolumn cation exchange were compared for (1) ability to discriminate between samples taken from diabetic and normal subjects; (2) correlation with each other; (3) stability over time at different temperatures; and (4) reproducibility between laboratories. The most discriminatory (10 samples from a diabetic and 10 samples from a normal group) was the microcolumn cation exchange method (t = 5.25; p < 0.001), but all were significantly different atp < 0.005. The intra-assay coefficient of variation was 1%-6%, except for the affinity column method which was 13% in normal subjects. High pressure liquid chromatography was used as a reference and the other assays correlated well (r=0.93-0.99). Storage at -80 ~ -20 ~ 4 ~ and 24 ~ showed marked differences. The thiobarbituric acid method results were stable except for 24 ~ Microcolumn cation exchange was labile under all conditions. Affinity column was stable for up to 15 days, only if samples were stored as whole blood. High pressure liquid chromatography showed an increase in haemoglobin Ala+b and a decrease in the haemoglobin Ale. Haemoglobin Ale was reproducible for 4 days when stored at 4 ~ and up to 11 days when stored at -80 ~ Samples exchanged between centres at 4 ~ and performed within 5 days by high pressure liquid chromatography for haemoglobin A1 and haemoglobin A1~ correlated well (r= 0.98 and 0.99). Samples exchanged between centres after storage (up to 40 days -80 ~ correlated (r = 0.99) by the thiobarbituric acid method. Thus, standards can be prepared for the thiobarbituric acid method and this method with high pressure liquid chromatography could be used to establish references for clinical assays.
Glycated Haemoglobin- Recent Developments and Review on Non-Glycemic Variables
Indian Journal of Forensic Medicine & Toxicology, 2021
Glycated hemoglobin (HbA1c) is the current tool for monitoring glycemic control once a diagnosis ofdiabetes is established. Its role in the diagnosis of diabetes has only recently come to attention. In the past,many international organizations have discussed the role of HbA1c in the diagnosis of diabetes and rejectedthis application as appropriately DCCT-aligned assays were not used or available globally. Consideringthe high biological variability, the dynamics of glucose, as well as the limitations of blood glucosemonitoring technology, at that time, the possibility of obtaining an integrated average glycemia value bythe measurement of a single biomarker elicited immense interest and provided a powerful tool in bothdiabetes research and clinical management. HbA1c testing was soon facilitated by the development of a newanalytical methodology that was suitable for use in clinical laboratories. However, a consensus statement in2007 on assays used to report HbA1c has now further streng...
Comparison of four chromatographic methods used for measurement of glycated hemoglobin
Revista Romana de Medicina de Laborator, 2016
This parameter’s results accuracy has a special importance in the management of diabetic patients since targets for optimal glycemic control are established using HbA1c values. Several error sources can influence the obtained value, some of them can be counteracted (ex. pipetting errors, storage), and others should be taken into consideration at the interpretation of the result (ex. presence of hemoglobin variants). The aim of this study was to compare four chromatographic methods regarding the costs and the influence of certain error sources on the accuracy of the result. Materials and methods: Samples and controls were analyzed using Variant I, Micromat II and In2it (Bio-Rad) systems, and the BIOMIDI reagent kit for HbA1c measurement. Results: Positive correlation could be observed comparing the results obtained using different methods, except the patients presenting elevated HbF. Pipetting errors modify the results up to 5% in case of Variant I, and up to 10% in case of Micromat ...
The Importance of Determining Irreversibly Glycosylated Hemoglobin in Diabetics
Diabetes, 1981
The concentration of glycohemoglobins (HbA1(a+b+c), HbA1,) was measured before and after incubation of normal and diabetic erythrocytes for 6 h at 37°C in saline. This procedure removes as much as 80-90% of the labile glucose-HbA0 adduct (labile HbA1,), thus allowing accurate estimation of irreversibly glycosylated hemoglobin (stable HbA1,). The concentration of HbA1 measured before such an incubation is total HbA1, (stable + labile). We determined the concentration of total, stable, and labile HbA1, in the same blood samples used to measure fasting plasma glucose (FPG) every day, for 4 consecutive days, in two groups of hospitalized insulin-treated diabetics. Group A subjects (N = 7) were type I, C-peptide negative, unstable diabetics, while group B subjects (N = 15) were type II, C-peptide positive, stable diabetics. Individual day-to-day variations of total HbA1, were wide in group A (Δ = 1.58 ± 0.14%), and slight in group B (Δ = 0.12 ± 0.01%; P < 0.001), paralleling similar p...
Measurement of glycosylated hemoglobins in black diabetic patients: a note of caution
Journal of the National Medical Association
Inspection of chromatography columns used for measurement of glycosylated hemoglobins revealed that blood samples from certain black diabetic patients produced two residual hemoglobin bands after chromatography rather than one. The levels of glycosylated hemoglobin were significantly lower in these subjects than in other diabetics. Further investigation revealed that each of these subjects had the hemoglobin AS or AC phenotype. The presence of hemoglobin S or C appears to cause spuriously low levels of glycosylated hemoglobin as determined by ion exchange chromatography. Other means to assess diabetic control should be used for patients with these abnormal hemoglobins. Measurement of glycosylated hemoglobin by ion-exchange chromatography is a valuable means of assessing control of hyperglycemia among patients with diabetes mellitus. ' Using a commercial
2005
Allen in 1958 showed chromatographic heterogeneity of hemoglobin A (1). Rahbar in Taheran first demonstrated elevation of minor hemoglobin in diabetes mellitus in 1968 (2). Trivelli introduced the column method of seperating out the fast hemoglobins in 1971 (3). Bunn and co-workers in 1978 pointed out that hemoglobin Alc is related to control of diabetes (4). The column method used in other countries, both the micro and macro columns have been expensive and as we shall discuss later, they are subject to more errors than the chemical method. Therefore, we have been interested in the chemical method that was described by Fluckiger and Winterhalter in 1976 (5). We modified this method to some extent to suit our needs and have tested it out over the past 5 years and found it to be working satisfactorily (6). This method has the advantage of not being influenced by changes in the ionic charge of the hemoglobin which occurs in many hemoglobinopathies and which occurs following aspirin or ...
Significance of Glycosylated Haemoglobin (Hb) in Diabetic Patients
The Southeast Asian Journal of Case Report and Review, 2014
In normal, non-diabetic control group subjects, mean glycosylated haemoglobin concentration is 6.68% and range is 5.02 to 7.93.In present study mean glycosylated haemoglobin concentration is 12.90. Glycosylated haemoglobin correlates significantly with the fasting, post prandial levels. Mean of fasting and post-prandial blood sugar level are 178.68 and 226.28 mg /dl respectively. Glycosylated haemoglobin value found higher in female-13.01 compare to make-12.86 Glycosylated haemoglobin values were higher in Juvenile onset diabetes (IDDM)-14, 20 than Maturity onset diabetes (NIDDM) 12.26. A Glycosylated haemoglobin value has no relation with the long complication of diabetes mellitus. Glycosylated haemoglobin concentration was found high in Insulin taking 15.26 than patients on oral hypoglycaemic agents 12.25 and on dietary restriction 7.81. Single Haemoglobin A1c measurement reflects the mean blood sugar concentration of the patient for the previous two to three months. Therefore, the glycosylated haemoglobin assay provides information about the degree of long term glucose control that is otherwise obtainable in the usual out patients setting. ION EXCHANGE RESIN method can be used routinely to estimate HbA1c in non-diabetic and diabetic patients. Periodic monitoring of HbA 1c should allow the assessment of chronic diabetic control on an out patients basis in a more objective manner than is now possible and enable one to evaluate various forms of therapy and the relationship between carbohydrate control and the progression of various diabetic sequele.
Brazilian Journal of Pharmaceutical Sciences, 2009
Hemoblobin A 1 c is the most important parameter for the monitoring of metabolic control of patients with diabetes mellitus. The purpose of this study was to adapt the Mono S method to a conventional HPLC system, allowing highly selective HbA 1 c determination without the acquisition of kits or the use of dedicated systems The results obtained were compared to the Tinaquant ® immune turbidimetric method and the Bio-Rad Variant ® chromatographic method. The developed method presented intra-study precision (C.V. %) of 1.39-3.65 and inter-study precision (C.V. %) of 2.80-3.02%. The determination coefficients among methods were: HPLC Mono S x Tinaquant ® : r 2 : 0.9856 (n=60) and HPLC Mono S x HPLC Bio-Rad Variant ® : r 2 : 0.9806 (n=16). A conversion equation between HPLC Mono S and Bio-Rad Variant ® was calculated allowing yielding comparable and interchangeable values. The HPLC Mono-S is a precise, low-cost method which yields similar values to the Bio-Rad Variant ® method on conventional HPLC equipment.