In diagnosing Wilson's disease, which serum protein should be measured?

In diagnosing Wilson's disease, measuring ceruloplasmin is crucial because this serum protein plays a significant role in copper metabolism. Wilson's disease is a genetic disorder characterized by excessive accumulation of copper in the body, which can lead to liver and neurological damage. Ceruloplasmin is a copper-carrying protein in the blood, and individuals with Wilson's disease typically have low levels of ceruloplasmin. This occurs because of the disrupted copper metabolism due to the defective ATP7B gene, which affects the liver's ability to excrete copper into bile and appropriately transport it in the bloodstream.

Low ceruloplasmin levels thus serve as an important biomarker for the diagnosis of Wilson's disease. While other serum proteins mentioned can provide useful clinical information, they do not specifically reflect the abnormal copper metabolism associated with Wilson's disease as effectively as ceruloplasmin does.