True iron deficiency occurs in the setting of malnutrition, impaired dietary absorption by medications, blood losses from phlebotomy, hemodialysis, and uremic platelets, whereas functional iron deficiency is caused by inflammation-induced hepcidin, the iron regulatory hormone that causes degradation of ferroportin (the iron exporter) in order to block iron release from iron recycling hepatic and splenic macrophages, hepatic iron stores, and dietary sources into the bloodstream [55]. The gene discussed is SLC40A1; the disease is Iron deficiency anemia.