**Question:** Plasma ceruloplasmin is a

A. Ferritin
B. Transferrin
C. Copper carrier
D. Alpha-2-glycoprotein

**Correct Answer:** D. Alpha-2-glycoprotein

**Core Concept:** Ceruloplasmin is an acute-phase protein, a type of plasma protein whose levels change in response to inflammation or infection. It plays a role in copper transport and is a copper-binding protein.

**Why the Correct Answer is Right:** Ceruloplasmin is an α2-macroglobulin, a glycoprotein synthesized primarily in the liver. Its main function is to transport copper ions in the plasma, preventing copper-induced oxidative damage to other proteins and tissues. As an acute-phase protein, its plasma concentration increases during inflammation or infection.

**Why Each Wrong Option is Incorrect:**

A. Ferritin is an iron storage protein, not involved in copper transport.
B. Transferrin is another plasma protein involved in iron transport, not copper transport.
C. Copper is not the primary function of ceruloplasmin, but rather its role in copper transport.

**Clinical Pearl / High-Yield Fact:** Ceruloplasmin is a marker of copper status and can indicate copper deficiency or excess. Low ceruloplasmin levels may be seen in Wilson's disease, a genetic disorder characterized by copper accumulation in the liver, brain, and other tissues.

In summary, ceruloplasmin is an α2-macroglobulin that primarily functions as a copper-transporting protein in plasma. Its elevation during inflammation or infection is a characteristic of acute-phase proteins.