The Efficiency of MCH Level for Differentiation between Normal and Alpha Thalassemia Trait from the Sample Group with Normal Hb Typing, Not Rule out Alpha-thalassemia Results in Sawanpracharak Hospital

Abstract

           Alpha-thalassemia is an inherited hemoglobin disorder characterized by reduced synthesis of alpha-globin chains, leading to ineffective erythropoiesis and anemia. Hb typing is routinely used to screen at-risk couples. However, standard Hb typing may not distinguish normal individuals from alpha-thalassemia traits, especially in cases with A2A pattern and microcytosis. These are often reported as “normal Hb typing, cannot rule out alpha-thalassemia,” requiring further confirmation by molecular testing, which may lead to unnecessary costs and delays when results are eventually normal. To evaluate the diagnostic performance of mean corpuscular hemoglobin (MCH) level in distinguishing normal individuals from those with inconclusive Hb typing results. It could decrease the unnecessary confirmation by molecular testing.  A retrospective study was conducted at a regional referral hospital in Thailand between September 2023 and October 2024. The medical records of 137 pregnant women and their partners with A2A hemoglobin typing results and inconclusive alpha-thalassemia carrier status were reviewed.

           MCH ≥ 22.2 pg showed 98.1% sensitivity, 96.4% specificity, 94.6% positive predictive value, 98.8% negative predictive value, and an overall diagnostic accuracy of 97.1% in identifying non-carriers. MCH ≥ 22.2 pg may serve as an effective tool for excluding normal individuals from patients with inconclusive Hb typing results.