Which laboratory tests are essential for the diagnosis of Wilson's Disease, and what are their expected findings?

Essential laboratory tests for diagnosing Wilson's disease include serum ceruloplasmin, 24-hour urinary copper excretion, and hepatic copper quantification via liver biopsy. Serum ceruloplasmin is typically low in Wilson's disease, often below 0.2 g/L, reflecting impaired copper transport ¹ (Langner and Denk, 2004). However, ceruloplasmin can be normal in some cases, especially in acute liver failure or inflammatory states, so it is not solely diagnostic ¹ (Aggarwal and Bhatt, 2013). 24-hour urinary copper excretion is elevated, usually exceeding 100 µg/24h, indicating increased free copper excretion due to defective biliary copper excretion ¹ (Chanpong and Dhawan, 2022). Liver biopsy with quantitative copper measurement remains the gold standard, showing hepatic copper concentrations greater than 250 µg/g dry weight, confirming copper accumulation ¹ (Langner and Denk, 2004). Additional supportive tests include slit-lamp examination for Kayser-Fleischer rings and genetic testing for ATP7B mutations, but these are adjuncts rather than primary laboratory diagnostics ¹ (Aggarwal and Bhatt, 2013). Serum free copper (non-ceruloplasmin-bound copper) is often elevated but less commonly used in routine diagnosis due to variability (Chanpong and Dhawan, 2022). Thus, the diagnostic approach integrates low ceruloplasmin, elevated urinary copper, and hepatic copper quantification to establish Wilson's disease.