Haematological indices as screening tool in distinguishing beta thalassemia trait and iron deficiency anaemia: Insights from a tertiary hospital study.

INTRODUCTION

Beta thalassemia trait (BTT) or heterozygous, is an inherited haematological disease characterised by more than 100 different mutations that lead to reduced beta chain formation. Distinguishing BTT from Iron deficiency anaemia (IDA) is challenging since both conditions are characterised by microcytic anaemia, have distinct underlying causes, and thus require different approaches in treating the condition. The aim of our study is to determine the utility of haematological indices as a screening marker in detecting cases of beta thalassemia carriers and differentiating it from IDA in our tertiary care hospital.

MATERIALS AND

METHODS

A retrospective analysis of the data at the Department of Pathology from January 2020 to December 2023 (4 years duration) was conducted. The analysis included a comparison of haematological parameters and RBC (Red Blood Cell) indices between the 78 cases of BTT and the 60 cases of IDA. Complete blood count (CBC) samples were collected in 2 ml of K2 EDTA (Di potassium Ethylene Diamine Tetra Acetic acid) vacutainer tube and processed in the automated haematology analyser, Sysmex XN 1000. Haematological parameters were analysed, and RBC indices were calculated. HPLC (High Performance Liquid Chromatography) analysis was done to detect HbA2/F levels. HbA2 levels more than 4% were diagnosed as BTT in our study. Various discriminating formulas, such as Srivastav index(SI), Red blood cell Distribution Width Index (RDWI), Shine and Lal index (SLI), Ricera index (RI), Green and King index (GKI), Mentzer index (MI), Sirdah Index (SI), Mean density of Haemoglobin/litre of blood (MDHL), England and Fraser index (EFI), Mean Cell Haemoglobin Density (MCHD), and Ehsani Index (EI), were applied to differentiate BTT cases from IDA Cases.

RESULTS

The mean haemoglobin in BTT was 10.8 g/dl, while in IDA, the mean Hb was 7.4 g/dl. The mean RBC count in BTT was 5.6 million/mm3, while in IDA it was 3.8 million/mm3. The values of haemoglobin (HB), Red blood cell Distribution Width - Coefficient of Variation (RDW-CV), Mean Corpuscular Haemoglobin Concentration (MCHC) and Mean Corpuscular Volume (MCV), between BTT cases and IDA cases showed statistical significance of p<0.05. Among the 11 discriminator formulas applied in our study, maximum accuracy was observed with the Ehsani index (84.06%), followed by the MI (82.61%). Maximum sensitivity was observed with RDWI (97.44%), followed by SLI (96.15%), EI (83.3%), and MI (79.45%). Youdens' score was highest in Ehsani index (68.33%), followed by MI (66.16 %), and the Green and King index (59.87%).

DISCUSSION: Among the various discriminator formulas applied, two indices, such as EI and MI showed the highest accuracy, and maximum score in Youdens' formula. Hence, in mass screening or in cases suspected to have IDA, either MI <13 or Ehsani index <17 with normal serum ferritin levels can be subjected to HPLC evaluation for the diagnosis of beta thalassemia carrier cases.