HAMP and anemia (phenotype): Targeting iron supplements to periods when low hepcidin concentrations indicated that children were ready and safe to receive iron successfully reduced the overall load of supplemental iron by 50% in the 12 mg/day screen-and-treat group and by 75% in the 6 mg/day screen-and-treat group, but was less efficacious than untargeted supplementation for the primary endpoint (haemoglobin concentration) and many secondary endpoints (including prevalence of anaemia and iron deficiency).