Stores iron in a soluble, non-toxic, readily available form. Important for iron homeostasis. Has ferroxidase activity (PubMed:9003196). Iron is taken up in the ferrous form and deposited as ferric hydroxides after oxidation (PubMed:9003196). Also plays a role in delivery of iron to cells (By similarity). Mediates iron uptake in capsule cells of the developing kidney (By similarity). Delivery to lysosomes is mediated by the cargo receptor NCOA4 for autophagic degradation and release of iron (PubMed:24695223, PubMed:26436293). {ECO:0000250|UniProtKB:P09528, ECO:0000269|PubMed:24695223, ECO:0000269|PubMed:26436293, ECO:0000269|PubMed:9003196}. This is the function of ENSG00000167996 (FTH1, ferritin heavy chain 1).