title: Hemoglobin A2 Lowered by Iron Deficiency and α -Thalassemia: Should Screening Recommendation for β -Thalassemia Change?
abstract: Screening for β -thalassemia trait (BTT) relies on measuring hemoglobin (Hb) A2. Since multiple factors can affect HbA2 levels, the screening can become unreliable. In 1356 healthy Arabs enrolled into a federally funded premarital BTT screening program, the effects of iron deficiency (ID), α (+)-thalassemia trait, gender, smoking, and tribalism on HbA2 were studied. The complete blood count and hemoglobin fractions were determined on the entire cohort; serum ferritin (<15  μ g/L) in 391 subjects was used to determine ID. BTT was present in 29 (2.1%) subjects (HbA2 > 3.5%). Among 77(20.3%) subjects with ID, the mean HbA2 (2.30 ± 0.23%) was 0.2% lower than in subjects without iron deficiency (2.50 ± 0.24%, P < 0.0001). In 65 (38%)/172 subjects with phenotypic α (+)-thalassemia trait, the mean HbA2 (2.43 ± 0.24%) was 0.13% lower than in subjects without α (+)-thalassemia trait, P < 0.0001. The mean HbA2 did not differ between males and females, smokers and nonsmokers, and between the tribes. Thus, 35 (2.6%) subjects with HbA2 between 3.2 and 3.5% were at a risk of false negative diagnosis of BTT. Since iron deficiency and α (+)-thalassemia are both common and both lower HbA2, modifications in screening recommendations for BTT are proposed.
authors.affiliation: Department of Medicine, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, Abu Dhabi, UAE.
authors.forename: Srdjan
authors.initials: S
authors.lastname: Denic
authors.forename: Mukesh M
authors.initials: MM
authors.lastname: Agarwal
authors.forename: Bayan
authors.initials: B
authors.lastname: Al Dabbagh
authors.forename: Awad
authors.initials: A
authors.lastname: El Essa
authors.forename: Mohamed
authors.initials: M
authors.lastname: Takala
authors.forename: Saad
authors.initials: S
authors.lastname: Showqi
authors.forename: Javed
authors.initials: J
authors.lastname: Yassin