Comparison of Erythrocyte Indices With A Newly Developed Mean Corpuscular Hemoglobin Concentration Based Formula for Differentiating β-Thalassemia Minor From Other Microcytic Hypochromic Anemia.

Background: Erythrocyte indices are measuring tools for differentiating beta thalassemia (β-thalassemia) minor from other microcytic hypochromic anemias using routine hematological parameters. Although indices such as the Mentzer Index, Shine and Lal (S&L), Green and King, Ehsani, and Srivastava are widely applied, diagnostic accuracy remains limited when compared to hemoglobin electrophoresis, which serves as the gold standard.

Objective: To compare the performance of two newly developed erythrocyte formulas for identifying β-thalassemia minor in comparison with five commonly used indices.

Methods: A cross-sectional study was conducted on 54 males and 214 female subjects with microcytic hypochromic anemia. Two new formulas were developed based on Mean Corpuscular Hemoglobin Concentration (MCHC), a parameter available in simple hematologic analyzers. The first formula was derived using the binary logistic regression method (21.33 + 0.9MCH-1.3MCHC), while the second was constructed as a ratio of Mean Corpuscular Volume (MCV) and MCHC (MCV/MCHC² × 100). Diagnostic performance was compared against other widely used erythrocyte indices.

Results: Shine and Lal Index had the highest sensitivity compared to all erythrocyte indices (98.65%). However, the newly developed formulas had the highest specificity (92.50% and 90.01%), positive predictive value (PPV) (93.48% and 91.55%), negative predictive value (NPV) (85.38% and 85.71%), accuracy (89.55% and 88.81%), Youden Index (79.66% and 77.85%), and Area Under the Curve (AUC) (0.932 and 0.934) compared to all erythrocyte indices.

Conclusion: The two new MCHC-based formulas had the best diagnostic performance compared with other erythrocyte indices, while Shine and Lal Index had the highest sensitivity.