Which is not involved in iron metabolism?

Transferrin is used for transpoing iron throughout the body BUT Transthyretin (Option a) - transpos Thyroxine & Retinol binding protein. So, it is NOT involved in iron metabolism WITH RESPECT TO OTHER OPTIONS: (Option b) Ceruloplasmin is a Cu containing enzyme also having Ferroxidase activity. Ferroxidase conves Fe +2 to Fe +3 (i.e. Ferrous to ferric). Ferric form of iron is required for transpo by transferrin in plasma. (Option c) Hepcidin regulates iron transpo in circulation. (Option d) Ferritin & Haemosiderin are proteins for iron storage. Haemosiderin has higher iron content than Ferritin.