Hepatocytes are the key source of hepcidin in the regulation of systemic iron homeostasis. Hepcidin synthesized in the kidney, central nervous system, lung, heart and other organs may be essential for regulation of local iron homeostasis but have a negligible effect on systemic iron homeostasis. For simplicity, not all known or putative sources of hepcidin are shown. Professional illustration by Debra T. Dartez.