In Wilson disease, which laboratory finding is typically decreased?

• A. Increased ceruloplasmin
• B. Decreased ceruloplasmin
• C. Normal ceruloplasmin
• D. Decreased ferritin

Answer: (B)

In Wilson disease, the problem is a defect in copper transport due to a mutation in ATP7B. This disrupts how copper is loaded onto ceruloplasmin and how copper is excreted into bile. Because copper cannot be properly incorporated, the circulating holo-ceruloplasmin (the copper-bound form) is reduced and is less secreted into the blood, so serum ceruloplasmin levels are typically low. Ceruloplasmin is the main copper-carrying protein made by the liver and also has ferroxidase activity; when it’s low, it reflects the impaired copper handling characteristic of the disease. Increased ceruloplasmin is not typical, and while ceruloplasmin can be normal in some cases, the classic finding used in diagnosis is decreased ceruloplasmin. Ferritin isn’t a defining feature of Wilson disease and isn’t consistently decreased.