What is the best initial investigation for Wilson's disease?

The best initial investigation for Wilson's disease is serum ceruloplasmin. Wilson's disease is a genetic disorder that leads to excessive accumulation of copper in the body, primarily affecting the liver, brain, and corneas. The most critical initial step in diagnosing this condition involves measuring ceruloplasmin levels in the serum.

Ceruloplasmin is a copper-carrying protein synthesized by the liver. In Wilson’s disease, due to the impaired excretion of copper, ceruloplasmin levels are typically low or absent. Therefore, low ceruloplasmin can indicate the presence of Wilson's disease and is a valuable diagnostic marker.

While 24-hour urinary copper excretion is significant in confirming the diagnosis, especially after suspicion arises, it is not typically used as the first investigation because it may not be elevated in early stages of the disease before liver damage is extensive. Liver biopsy can provide definitive information about copper content in the liver but is more invasive and is usually reserved for cases where the diagnosis is uncertain or to assess the extent of liver damage. Genetic testing can confirm mutations in the ATP7B gene responsible for Wilson's disease, but it is also not the first step. Thus, serum ceruloplasmin serves as a practical and