Ceruloplasmin is a copper-containing plasma protein with ferroxidase activity. A patient with Wilson's disease (ATP7B mutation) has low serum ceruloplasmin and corneal Kayser-Fleischer rings from copper deposition. The ferroxidase activity of ceruloplasmin is clinically important because it:

• A Oxidizes Cu+ to Cu2+ for hepatic storage in metallothionein
• B Reduces ferric iron in the gut lumen to ferrous iron for intestinal absorption
• C Catalyzes copper incorporation into cytochrome c oxidase (Complex IV)
• D Oxidizes Fe2+ to Fe3+, enabling transferrin to bind iron for transport and preventing Fe2+-driven Fenton reaction generating hydroxyl radicals ✓

Explanation

Ceruloplasmin's ferroxidase activity converts Fe2+ (ferrous) to Fe3+ (ferric) in plasma; this is essential for loading iron onto apotransferrin, which only binds Fe3+. More critically, free Fe2+ drives the Fenton reaction (Fe2+ + H2O2 → Fe3+ + OH- + OH•) generating highly toxic hydroxyl radicals. In Wilson's disease, ceruloplasmin deficiency impairs ferroxidase activity, contributing to oxidative stress from both copper and iron dysregulation. Aceruloplasminemia (rare genetic ferroxidase deficiency) causes iron accumulation in brain, liver, and pancreas with neurodegeneration, diabetes, and retinal degeneration despite normal copper metabolism.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.