Study design and hepcidin and iron status at the start and end of the malaria season. (A) Study design at the Gambian site. (B) Study design at the Kenyan site. (C) Plasma hepcidin levels at the start and end of the season. (D) Proportion of iron-deficient children at the start and end of the season. (E) Ferritin levels at the start and end of the season. (F) Soluble transferrin receptor (sTfR) levels at the start and end of the season. CBC indicates complete blood count. Geometric means are presented for continuous variables. The same individual study participants contributed data at the start and end of the season. All analyses were adjusted for age.