Effectiveness of osmotic fragility screening with varying saline concentration in detecting B-Thalassemia trait

ABSTRACT

Thalassemia is a major health problem in Iran. The prevalence of thalassemia minor is high and screening program for detecting beta -thalassemia trait has been established in southern parts of Iran since 1992. To determine the efficacy of naked-eye single-tube red cell osmotic fragility test [OFT] as a screening test for beta -thalassemia trait. Three different concentrations [0.36%, 0.37% and 0.38%] of buffered saline solutions were used. OFT were applied to three groups of subjects: 50 normal individuals, 50 subjects with genetically proven beta -thalassemia trait, and 15 patients with proved iron-deficiency anemia. The results demonstrated that 0.37% saline was the best solution for OFT. It could detect 98% of heterozygous beta -thalassemia patients compared to 96% and 84% detection rate obtained with respective 0.36% and 0.38% saline. Specificity of OFT with 0.37% saline was 96% whereas that of 0.36% and 0.38% saline were 84% and 94%, respectively. The OFT with 0.37% saline was also positive in 5 [33.3%] patients with iron-deficiency anemia. OFT done with 0.37% buffered saline solution provides more accurate results. Since the test is inexpensive and practical it might be considered as the single screening test to be used in areas with limited laboratory facilities and economic resources