Effect of megaloblastic anemia on hemoglobin A and diagnosis of β-thalassemia trait.

CONTEXT

β-thalassemia trait is usually diagnosed by raised hemoglobin A (HbA). The presence of megaloblastic anemia can cause an increase in HbA and create a diagnostic dilemma. Here, we have analyzed the effect of vitamin B12 and folic acid supplementation on HbA and diagnosis of β-thalassemia trait in cases of megaloblastic anemia with raised HbA.

MATERIALS AND METHODS

Cases of megaloblastic anemia with raised HbA on high-performance liquid chromatography (HPLC) were supplemented with vitamin B12 and folic acid. Post-treatment evaluation was done after 2 months. Cases showing adequate hematological response were subjected to statistical analysis. Based on post-treatment HbA value, the cases were diagnosed as normal, borderline raised HbA, or β-thalassemia trait. Pre- and post-treatment values of red cell parameters and HbA were analyzed.

RESULTS

There was a significant decrease in HbA value after vitamin B12 and folic acid supplementation. The diagnosis was changed in 70.97% of the cases after treatment. The chance of inconclusive diagnosis was decreased from more than 50% to less than 10%. Pre-treatment mean corpuscular volume (MCV) and HbA% showed a significant difference between the thalassemic and normal groups.

CONCLUSIONS

Megaloblastic anemia can lead to false-positive diagnosis of β-thalassemia trait on HPLC. Repeat HPLC should be done after adequate supplementation of vitamin B12 and folic acid in cases of megaloblastic anemia with raised HbA. Red cell parameters are not helpful to suspect β-thalassemia trait in presence of megaloblastic anemia. However, HbA% on HPLC can be a useful parameter to suspect or exclude β-thalassemia trait in cases of megaloblastic anemia.