Comparative study of sickling test, solubility test, and hemoglobin electrophoresis in sickle cell anemia

Abstract

Abstract Background: Madhya Pradesh, a state in India, bears the highest number of sickle cell anemia (SCA) cases, particularly among its tribal communities. The diagnosis of suspected SCA cases involves utilizing several methods. The sickling test operates on the principle of hemoglobin S (HbS) polymerization upon deoxygenation. By contrast, the solubility test involves the reduction of HbS using sodium hydrosulfite, followed by precipitation of lysed red blood cells. Hemoglobin (Hb) electrophoresis identifies Hb variants based on their migration in an electric field. Our objective was to assess the efficacy of sickling and solubility tests as screening tools for detecting SCA, comparing them against capillary Hb electrophoresis, which is considered the gold standard. Materials and Methods: All individuals suspected of having SCA between 2022 and 2023 were enrolled in the study. Clinical information, peripheral blood smear analysis, sickling test, solubility test, and capillary Hb electrophoresis were conducted, and the results were compared. Results: Of 250 cases assessed, Hb electrophoresis identified 225 cases of SCA, resulting in a sickle cell disease to sickle cell trait (SCT) ratio of 1:1.36 and a male-to-female ratio of 1:1.33. The highest number of cases were observed in the age group from 21 to 30 years. Generalized weakness (77%) and abdominal pain (52%) were the most frequently reported symptoms. The sickling test demonstrated a sensitivity, specificity, and diagnostic accuracy of 91.5%, 72%, and 89%, respectively, compared with Hb electrophoresis. The solubility test yielded values of 76.5%, 68%, and 75% for sensitivity, specificity, and diagnostic accuracy, while peripheral smear analysis showed 36%, 25%, and 42%, respectively. Conclusion: The sickling test displayed superior sensitivity and diagnostic accuracy compared with the solubility test, with no significant disparity in specificity between these two methods. Notably, the solubility test exhibited a higher incidence of false-negative results for SCT. Therefore, the sickling test is the preferred screening method for SCA.