Answer and Critique (Correct Answer =2)
This Week’s Question #421 - Diabetes In Control.com Newsletter
A patient calls you up and tells you that they do “double red cell” donation to the American Red Cross every 4 months. They know that A1c is about glucose on the blood cells and want to know if this can affect their A1c level.
The donation of Red Blood Cells can cause:
Discussion
The donation of red cells does indeed have an effect on A1c levels. Since the test measures a type of hemoglobin in the red blood cell that attaches to glucose, the amount of red blood cells in the blood has a direct correlation to A1c levels.
We already know that patients who have a high turnover in red blood cells, such as those with sickle cell anemia, have an artificially low A1c, because they are making a higher number of new red blood cells. This is similar to what happens when red cells are lost due to a blood donation. A normal donation may require up to four weeks of new red cell production and a double donation may take eight weeks.
It takes about 8 weeks for new red blood cells to attach to glucose and raise the A1c to pre-donation levels.
A1c levels can actually be decreased by 4 to 8% for the first 4 to 6 weeks after a donation, and if a double donation A1c can be as much as 16% off for even a longer time.
Based on this information it is important to tell your patients that they should have their A1c done just prior to the donation, and more importantly we should ask if they have donated blood when they see us for an appointment.
Information from Practical Diabetology June 2008
Richard Benjamin, MD, CMO American Red Cross Blood Services
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