GSTM1 and Iron deficiency anemia: Notably, patients who were referred were significantly older (median 60 vs 57 years, p < 0.001), had significantly higher f-Hb (≥ 10 μg/g 37.9% vs. 1.9%, p < 0.001), were more likely to be anaemic (22.4% vs 17.6%, p < 0.001), and had a greater proportion of iron deficiency anaemia (6.8% vs 3.9%, p < 0.001).