I would like to know if just being a sickle cell career could affect HbA1c levels.
The majority of assays used to detect HbA1c are not affected by Hb S interference, but it depends on what methodology you are using to measure HbA1c. Being heterozygous for Hb S could decrease the amount of HbA1c recognized as such if you are using a methodology such as HPLC. This is because HbA1c is a post translational modification product of Hb A and will have a particular retention time in the column. The glycated form of Hb S will have a different retention time than HbA1c. If a Sickle Cell carrier has 50% Hb A and 40% Hb S, their measured HbA1c could be as much as 40% lower than if they were not a Sickle Cell carrier. However, the majority of assays currently used to detect HbA1c are not affected by Hb S intereference. This is a good resource detailing which insturments and assays are affected by Hb S interference: http://www.ngsp.org/interf.asp
Thanks, Hung for the information.
Please, could you reccommend any more detailed references with regards to my question.
Thanks
If you are measuring HbA1c, please also see the following for info on other hemoglobin variants that can cause issues.
http://www.ngsp.org/interf.asp
Chesinta, This link provides a long list of articles addressing specific assays and whether or not there is Hb S intereference. The list of articles is too long to repost here. http://www.ngsp.org/factors.asp
@ Hung, thanks for the more extensive list as it sites some references for the specific methods as well, I will look at the references. I realise some of the analyser I know are used clinically for HbA1c measuremnt are not listed here, and was wondering if you happen to know any more references you can point me to.
Thanks so much
Chesie
@ Elizabeth, thanks for pointing me to the list.
Hi Chesinta,
I'm afraid I am not familiar with those assays that are missing from the list. Those 20 are pretty widely used.
Validity of A1c in the presence of a Hb Variant depends on two factors: Assay Interference and Clinical Interpretation. Although most A1c methods do not show assay interference with Hb S trait. However Hb S trait is associated with altered RBC half life. Thus the A1c results in Sickle trait cannot be fully compared with a subject without variant Hb. Glycation rates are different in various Hb Variants as compared to normal adult Hb.
I hope this helps.
Sutirtha states that sickle cell trait is associated with an altered RBC life span. I am not aware of any published data that would support this assertion. To my knowledge, although not very recent, the studies by McCurdy (1969) and Barbedo and McCurdy (1974) showing that the life span of AS RBC is normal have not been challenged by more recently published data.
Blood. 1969;33:214-24; Acta Haematol 1974;51:339–343
This is a controversial area. But a recent article by Mollinaro et al. states that that RBC survival time is altered in Hb S trait.
Mollinaro et al. Impact of hemoglobin variants on Hb A1c interpretation: Do we assume too much? MLO 2012
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