1. Low serum ceruloplasmin levels < 20 mg/dL (Normal range 20-50 mg/dL).
2. Kayser - Fleischer rings in eyes.
3. High liver copper levels > 250 micrograms/g dry weight (Normal range <35 micrograms/g dry weight).
4. High 24 hr urinary copper levels > 100 micrograms /d or > 1.6 mmol/d (Normal range <50 micrograms/d or < 0.8 mmol/d).
5. Radioisotope copper studies using 64Cu, 67Cu or 65Cu, which assesses ability to incorporate copper into ceruloplasmin.

Liver biopsy is very helpful for making the diagnosis of Wilson's disease, especially in patients with normal ceruloplasmin levels and no evidence of Kayser-Fleischer rings. Hepatic copper concentrations greater than 250 micrograms/g dry weight (normal is <35 micrograms) are often found in untreated patients with Wilson's disease.

Identification of the Wilson's disease gene has made molecular diagnosis of this disease possible, but population-based screening is not feasible or recommended at this time. Genetic testing probably has had its biggest impact on screening of first-degree relatives of an affected person.