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Glycosylated hemoglobin
Last reviewed: 23.04.2024
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The reference value (norm) of glycosylated hemoglobin (HbA 1 c ) in the blood - 4,0-5,2% of the total hemoglobin.
HbA 1 c is the glycosylated form of HbA present in the red blood cells. At high concentrations of glucose in the blood, it enters into a non-enzymatic interaction with plasma proteins with the formation of Schiff bases, including hemoglobin. The degree of glycosylation of hemoglobin depends on the concentration of glucose in the blood and on the duration of contact of glucose with hemoglobin. Therefore, the amount of HbA 1 c is proportional to the concentration of glucose and the duration of incubation (contact with erythrocytes). Measurement of the concentration of HbA 1 c allows retrospectively to estimate the level of hyperglycemia in diabetes mellitus. In fact, glycosylated hemoglobin consists of three components: HbA 1a, HbA 1 b and HbA 1 c. HbA 1 c has a higher correlation with the severity of hyperglycemia in diabetic patients.
The concentration of HbA 1 c in erythrocytes is the integral index of the state of carbohydrate metabolism for the preceding 6-8 weeks. The results of the study are assessed as follows: 4-6% - good compensation for diabetes mellitus in the last 1-1.5 months, 6.2-7.5% - satisfactory, more than 7.5% - unsatisfactory. To evaluate the effectiveness of treatment, it is advisable to repeat the study after 2-3 months.
Lozhnoponizhennye values HbA 1 c occur in uremia, chronic and acute hemorrhages, as well as conditions involving reduction in life expectancy of erythrocytes (e.g., hemolytic anemia).
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