In this study, macrocytic anemia due to FAD was defined as having an MCV ≥100 fL and folic acid ≤6 ng/mL; pernicious anemia as having MCV ≥100 fL, vitamin B12<200 pg/mL, and serum gastric parietal cell antibody positivity; iron deficiency anemia as having MCV<80 fL and iron<60 μg/dL; and thalassemia trait as having MCV<74 fL, red blood cell (RBC) count>5.0 × 10(12)/L, and Mentzer index (MCV/RBC)<13.