Differentiation of Beta Thalassemia Trait and Iron Deficiency Anaemia by Red Cell Indices

Beta thalassaemia trait (β-TT) and iron deficiency anaemia (IDA) are the most frequent causes of hypochromic microcytic anaemia in Bangladesh. Differentiation between βTT and IDA is important for proper treatment of patients. Red blood cell (RBC) indices obtained from automated cell counter can be used to differentiate between two. Objective: To compare among three RBC indices; red cell distribution width (RDW), red cell distribution width index (RDWI) and Mentzer’s index to differentiate between βTT and IDA. Materials and Methods: This cross-sectional comparative study was conducted on 50 diagnosed cases of β-TT and 50 cases of IDA at the department of pathology, BNS Patenga, Bangladesh from January 2016 to December 2017. Patients with Hb <6.0 gm/dl was excluded because below this level IDA and β-TT morphologically become very much distinguishable. RDW, RDWI and Mentzer’s index were calculated from the automated cell counter. Sensitivity, specificity, positive predictive value and negative predictive value were calculated to compare diagnostic value of the indices. Results: Mentzer’s index was found the most reliable index as it had the highest sensitivity 95.1% and specificity 84.8% for detecting IDA. RDWI showed much lower sensitivity 91.2% and specificity 66.2% while RDW showed sensitivity and specificity of 83.2% and 61.1% respectively. Conclusion: Mentzer’s index is a reliable and useful index for differentiation between IDA and β-TT compared to other two indices. Journal of Armed Forces Medical College Bangladesh Vol.13(2) 2017: 39-41