GSTM1 and Iron deficiency anemia: When classified by the combination of serum ferritin, serum iron, and hemoglobin values, 48.9% of the underweight children were recognized as anemic (Hb concentration<11g/dl), 33.3% in a state of iron deficiency (serum iron<60μmol/L), and 5.6% with low iron stores (serum ferritin <12μg/L).There was no significant difference in the prevalence of iron deficiency between two groups (P=0.345).