A 55-year-old man with hereditary hemochromatosis has serum transferrin saturation of 85 percent and elevated ferritin. Transferrin is the principal iron-transport protein in plasma. Which form of iron binds to transferrin for transport?
- A Ferrous iron (Fe2+)
- B Heme iron
- C Ferric iron (Fe3+) ✓
- D Iron-sulfur cluster
Correct answer: C. Ferric iron (Fe3+)
Explanation
Transferrin binds ferric iron (Fe3+), not ferrous iron. Before binding, ferrous iron must be oxidized to ferric iron by ceruloplasmin (ferroxidase). Transferrin transports Fe3+ to cells, where it is internalized via transferrin receptor-mediated endocytosis and released in the acidic endosome, then reduced to Fe2+ for storage or use.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.