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Prevalence of elevated hemoglobin A2 measured by the CAPILLARYS system
Zhaohai Yang1, Carolyn H Chaffin, Pattye L Easley
1Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35233, USA.
American Journal of Clinical Pathology
|December 20, 2008
Summary
Elevated Hemoglobin A2 levels during pregnancy may not always indicate beta-thalassemia trait. Further investigation is needed for accurate diagnosis in pregnant individuals.
Area of Science:
- Hematology
- Clinical Chemistry
- Genetics
Background:
- Hemoglobin A2 (HbA2) electrophoresis is a standard method for prenatal screening of beta-thalassemia trait (betaTT).
- Elevated HbA2 levels can be caused by hemoglobinopathies or other factors.
- Pregnancy can influence HbA2 levels, potentially affecting screening accuracy.
Purpose of the Study:
- To evaluate the diagnostic accuracy of HbA2 electrophoresis for beta-thalassemia trait in pregnant women.
- To compare the prevalence of elevated HbA2 levels without betaTT in pregnant versus nonpregnant individuals.
Main Methods:
- Retrospective review of Hemoglobin capillary electrophoresis data.
- Analysis of Red Blood Cell (RBC) indices alongside HbA2 levels.
- Comparison of results between pregnant and nonpregnant patient groups.
Main Results:
- Of 122 cases with elevated HbA2, 79 were due to hemoglobinopathies (mostly HbS).
- In pregnant women (HbAA-pregnancy group), 3 of 36 cases with elevated HbA2 had betaTT; 29 had normal RBC indices.
- A significantly higher number of pregnant women without betaTT showed elevated HbA2 compared to nonpregnant individuals.
- Using a higher HbA2 cutoff (3.5%) reduced false positives in pregnant women.
Conclusions:
- A significant proportion of pregnant women exhibit elevated HbA2 levels without evidence of beta-thalassemia trait.
- Pregnancy status influences the interpretation of HbA2 electrophoresis results.
- Adjusting HbA2 cutoffs or considering RBC indices may improve diagnostic accuracy in pregnant populations.
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