An Automated Hb A_2 Analyzer, HLC-723G7, for Diagnosis of β-Thalassemia

We investigated the usefulness of an automated analyzer, the HLC-723G7, for determination of Hb A2 in the diagnosis of β-thalassemia. The analyzer was used for 250 Thai subjects who were either normal or were diagnosed with microcytic hypochromia based on hematological findings. An intra-assay precision test of normal subject (Hb A_2 = 2.78%) and that (Hb A_2 = 5.90%) with β-thalassemia revealed as coefficients of variation (CV%) of 3.2% and 0.95%, respectively. Samples were kept stable at 4℃ for at least 10 days. The Hb A_2 values obtained by the HLC-723G7 showed good correlation with those obtained by DEAE-HPLC with the coefficient of correlation (r) being 0.940, the coefficient of determination (R^2) 0.884, and the equation of the regression line Y_ = 1.057X_-0.248. The subjects with a higher Hb A_2 value than about 4% were suspected of having β-thalassemia based on hematological findings. Most of those with a lower or relatively lower Hb A_2 value than the normal range (2.3-3.5%) or 4% and hematological abnormalities were considered to be suffering from α-thalassemia-1, α-thalassemia-2 or iron deficiency anemia. However, a confirmed diagnosis must be made by the further study of the red cell morphology, clinical manifestations and by the DNA analysis