Ceruloplasmin is a copper-binding protein produced by the liver that plays a crucial role in copper metabolism and transport throughout the body. This test measures ceruloplasmin levels in the blood and is primarily used to diagnose Wilson's disease, a rare genetic disorder that causes copper to accumulate in the liver, brain, and other organs. Low ceruloplasmin levels, along with other clinical findings, strongly suggest Wilson's disease, which can cause liver disease, neurological problems, and psychiatric symptoms if left untreated. Ceruloplasmin also acts as an acute-phase reactant, meaning levels can increase during inflammation, infection, or certain cancers. This test is commonly ordered when evaluating unexplained liver disease, neurological symptoms, or when Wilson's disease is suspected based on family history or clinical presentation. Early diagnosis of Wilson's disease is critical for preventing irreversible organ damage.