THE APPLICATION OF MCH FOR DIFFERENTIATION OF NORMAL FROM NORMAL Hb TYPING, NOT RULE OUT α-THALASSEMIA

Abstract

Thalassemia is the most common genetic disease in Thailand. Its gene could be passed on to the off spring, so laboratory investigation plays an important role on control and prevention of severe thalassemia. Hemoglobin (Hb) typing method must be performed in order to find a risk coupler. In normal people, the results of Hb Typing will be A2A, which must be considered in conjunction with red blood cell indices.
If red blood cell indices are normal reported A2A Normal, if red blood cell are abnormal reported A2A Normal Hb Typing, not rule out α-thalassemia. Because Hb Typing method cannot separate α-thalassemia with Normal, So be confirmed by PCR. This causes additional a waste of budget, increased workload, and patients wasting time waiting. If there is a value used as a dividing point to separate normal people from Normal Hb Typing, not rule out α-thalassemia group, it will reduce this problem.
The aim of this study is to apply Mean corpuscular hemoglobin (MCH) level to exclude normal people from Normal Hb Typing, not rule out α-thalassemia group when Hb typing result was obvious, opportunities to reduce confirmation by PCR.  A total of 125 samples were collected to diagnose α-thalassemia trait and Normal Hb Typing, not rule out α-thalassemia was reported. Based on the ROC curve, the best cut-off level of MCH in predicting the α-thalassemia trait was 22.2 picrograms. The MCH level ≥ 22.2 picrograms gave the sensitivity of 92.0% and specificity of 86.0% for differentiation of normal from Normal Hb Typing, not rule out α-thalassemia. The positive predictive value and negative predictive value were 90.8 % and 87.8% respectively. In conclusion, MCH level ≥ 22.2 picrograms is a good tool for differentiation of normal from Normal Hb Typing, not rule out α-thalassemia.