Feasibility of four discriminant functions for identifying hemoglobin E disorders: Experience in 114 Thai pregnant subjects

Hemoglobin disorder, especially for hemoglobin E disorder, is the major problem of Thailand. Based on the modern electronic cell counter, quick differential screenings by discriminant functions have been widely developed. However, originally, these DFs were mostly applied to the differentiation of iron deficiency anemia from beta thalassemia. Only a few studies on its property in screening for other abnormal hemoglobin have been reported. The 4 most widely used discriminant functions were
evaluated for their abilities to identify HbE - containing blood
samples among 114 Thai pregnant subjects. The functions evaluated were: a) F 1= 0.01 x MCH X (MCV)2, b) F2 = RDW x MCH x (MCV)2 / Hb x 100, c) F3 = MCV/RBC and d) F4 = MCHC/RBC.
Conclusively based primarily on hemoglobin typing as A2A, EA and EE, the means of F1 F2, F3 and F4 of A2A > EA> EE. The sensitivity, specificity, false positive and false negative of using F4 in identification of EE group are100 %, 95.2 %, 4.8 % and 0 %, respectively. In conclusion, the four tested DFs are not good screening tool of the normal (A2A) from abnormal (disease: EE and carrier: EA) but F4 might be used as screening tool for disease (EE). Due to the fact that these DFs do not pose good diagnostic property in screening for abnormal and require automated analyzer.