What is adult hemoglobin composed of?
HbA, Hb A2 and Hb F. Hb A contains serveral minor hemoglobin components, identified as Hb A1a, Hb A1b and Hb A1c.
What are the modifications of Hb A collectively referred to as?
glycated hemoglobin, glycosylated hemoglobin, Hb A1c g, "fast hemoglobin" or glycohemoglobin.
What are elevations of glycosylated Hb A1c the result of?
Prolonged hyperglycemia usually of 60-90 days duration. Leading to glycation reaction between glucose and Hb A.
Why is the measurement of Hb A1c useful in determining compliance with therapy & the extent to which satisfactory diabetic control has been achieved?
Diabetics have a higher proportion of Hb A1c than do normal individuals. The measurement of glycated hemoglobin provides an index of the patient's average blood glucose over a two month period.
Is there an inverse relationship between the levels of Hb A1c and the rate at which complications developed?
No. There is a linear relationship between the levels of Hb A1c and the rate at which complications develop. Hb A1c < 8% is the threshold below which most complications can be prevented. Therapy for DM should focus on metabolic control to lower Hb A1c while avoiding hypoglycemic episodes.
How do we measure the levels of Advanced Glycosylation End products (AGE)?
The A1c level reflects the levels of advanced glycosylation end products. These glycosylated enzymes/proteins have been linked to many of the complications of DM.
How does the half-life of albumin relate to the insight generated by measuring glycated albumin levels?
fructosamine is a measure of glycemic control during the 3 week period prior to sampling since the half-life of albumin is two to three weeks.
Can all serum proteins be glycated? Why choose albumin as the target of glycosylation levels?
Can all be glycated & since albumin is the most abundant protein in the serum, fructosamine is largely a measurement of glycated albumin.
Urine Microalbumin Test
since DM can lead to renal complications w/ loss of albumin into the urine (diabetic nephropathy), albumin can be seen in the urine (microalbuminuria). EARLY diabetic nephropathy treatable by better control of the patient's blood glucose levels & blood pressure.