Diabetes Mellitus, a chronic disease characterized by hyperglycemia of the eyes, heart, kidneys, blood vessels and other organ systems. The disease is accompanied by carbohydrate, lipid & protein metabolism disturbances. Traditional methods of assessing glycemic control in diabetes is by analyzing the medical history, performing a physical examination and measuring blood and urine glucose, while extremely important for routine care have only limited value as indices of long term glycemic status. It is only with the development of glycated Hb (GHb), testing that accurate, objective measure of long term glycemic status is possible.
The terms “glycated hemoglobin” also called glycohemoglobin or glycosylated Hb – refers to a series of stable minor Hb components that are formed slowly and non- enzymatically from Hb and glucose. Of the fast moving Hb’s identified in the 1950’s, HbA1C is present in greatest quantity in both normal and diabetic individuals. HbA1C is formed by the nonenzymatic glycation of free amino groups at the ‘N’ terminal of the amino acid valine of the Hb “B” chain.
The glucose remains bound during the erythrocyte life cycle. It is related to the degree of blood glucose level elevation and the time interval over which this occurs as well as the erythrocyte life span. The HbA1C level correlates with the mean glucose concentration prevailing in the course of the patient’s recent history (approximately 6-8 weeks). Therefore provides much more reliable information for glycemic monitoring than do determination of blood glucose or urinary glucose.
Test Principle
The HbA1C determination is based on the turbidimetric inhibition immunoassay for haemolysed whole blood. The HbA1C in the sample reacts with the anti HbA1C antibody to form a soluble antigenantibody complex. The polyhaptens react with excess anti HbA1C antibodies to form an insoluble antibody polyhapten complex, which can be determined turbidimetrically. Liberated Hemoglobin from the haemolysed sample is correlated to a derivative having a characteristic spectrum and subsequently determined.
The terms “glycated hemoglobin” also called glycohemoglobin or glycosylated Hb – refers to a series of stable minor Hb components that are formed slowly and non- enzymatically from Hb and glucose. Of the fast moving Hb’s identified in the 1950’s, HbA1C is present in greatest quantity in both normal and diabetic individuals. HbA1C is formed by the nonenzymatic glycation of free amino groups at the ‘N’ terminal of the amino acid valine of the Hb “B” chain.
The glucose remains bound during the erythrocyte life cycle. It is related to the degree of blood glucose level elevation and the time interval over which this occurs as well as the erythrocyte life span. The HbA1C level correlates with the mean glucose concentration prevailing in the course of the patient’s recent history (approximately 6-8 weeks). Therefore provides much more reliable information for glycemic monitoring than do determination of blood glucose or urinary glucose.
Test Principle
The HbA1C determination is based on the turbidimetric inhibition immunoassay for haemolysed whole blood. The HbA1C in the sample reacts with the anti HbA1C antibody to form a soluble antigenantibody complex. The polyhaptens react with excess anti HbA1C antibodies to form an insoluble antibody polyhapten complex, which can be determined turbidimetrically. Liberated Hemoglobin from the haemolysed sample is correlated to a derivative having a characteristic spectrum and subsequently determined.
Normal reference range is 4.3 to 6.0 %. However, good control for a diabetic patient is considered as, an HbA1C value below 7.0 %. Glycohemoglobin is a valuable tool for assessing glycemic control and is routinely used in the care of persons with diabetes. Measurement of GHb has also shown useful research applications facilitating studies requiring objective assessment of long term glucose control. Reports have shown that regular monitoring of GHb among diabetic patients can facilitate changes in treatment resulting in improved glycemic control.
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