What investigations are used to diagnose Wilson's disease?

Diagnostic Investigations for Wilson's Disease

The diagnosis of Wilson's disease requires a comprehensive panel of tests including serum ceruloplasmin, 24-hour urinary copper excretion, hepatic copper quantification, slit-lamp examination for Kayser-Fleischer rings, and in some cases genetic testing, as no single test is sufficient for definitive diagnosis. 1

Initial Diagnostic Tests

Biochemical Tests

• Serum ceruloplasmin:

  • Values <0.1 g/L (<10 mg/dL) strongly suggest Wilson's disease 1
  • Important limitations: normal levels in 15-36% of children with Wilson's disease, and potential false lows in malabsorption syndromes, aceruloplasminemia, heterozygous carriers, and severe hepatic insufficiency 1

• 24-hour urinary copper excretion:

  • Values >1.6 μmol/24h (>100 μg/24h) are typically diagnostic in symptomatic patients 1
  • A threshold of 40 μg/24h (0.6 μmol/24h) is recommended for screening 1
  • Proper collection techniques are essential to avoid contamination 2

• Serum copper and non-ceruloplasmin bound copper:

  • Calculate non-ceruloplasmin bound copper = serum copper (μg/dL) - 3 × ceruloplasmin (mg/dL) 1
  • Values >250 μg/L suggest Wilson's disease 1

• Liver function tests:

  • Serum aminotransferases are generally abnormal but may be only mildly elevated 2
  • In acute liver failure due to Wilson's disease, look for:
    • Modest elevations in serum aminotransferases
    • Low serum alkaline phosphatase (typically 40 IU/L)
    • Ratio of alkaline phosphatase to bilirubin <2
    • AST:ALT ratio >2.2 2

Physical Examination

• Slit-lamp examination for Kayser-Fleischer rings by a skilled examiner 2
  • Present in virtually all patients with neurological manifestations
  • Absent in up to 50% of patients with hepatic Wilson's disease 1
  • The absence of rings does not exclude the diagnosis 2

Advanced Diagnostic Tests

Liver Biopsy

• Hepatic copper quantification:

  • Values >4 μmol/g dry weight are diagnostic 1
  • Normal levels (<0.64-0.8 μmol/g) almost always exclude Wilson's disease 1
  • Critical when diagnosis is not straightforward 2

• Histological findings:

  • Steatosis, glycogenated nuclei in hepatocytes, focal hepatocellular necrosis
  • Later stages: fibrosis and cirrhosis 2
  • Histochemical detection of copper is variable and not reliable for screening 2

Imaging Studies

• Brain MRI in patients with neurological symptoms:
  • Hyperintensity on T2 MRI in the basal ganglia region 2
  • "Face of the giant panda" sign (characteristic but found only in a minority of patients) 2
  • Hyperintensities in tectal-plate and central pons, and simultaneous involvement of basal ganglia, thalamus, and brainstem are virtually pathognomonic 2

Genetic Testing

• ATP7B gene mutation analysis:

  • Most useful for screening first-degree relatives 1
  • Challenging due to >600 different mutations 1
  • Direct molecular-genetic diagnosis is difficult because most patients are compound heterozygotes 2
  • Identification of two mutations will confirm the diagnosis 2

• Haplotype studies:

  • Based on polymorphisms surrounding the Wilson's disease gene 2
  • Requires identification of an index patient within the family 2

Diagnostic Algorithms

Leipzig Scoring System

• Score ≥4: Diagnosis established
• Score 3: Possible diagnosis
• Score ≤2: Diagnosis unlikely 1

Special Situations

Acute Liver Failure

Look for:

• Markedly elevated serum copper (usually 200 μg/dL or 31.5 μmol/L)
• Coombs-negative hemolysis
• Low alkaline phosphatase
• Ratio of alkaline phosphatase to bilirubin <2 1

Family Screening

All first-degree relatives of newly diagnosed patients must be screened with:

• Brief history and physical examination
• Serum copper and ceruloplasmin
• Liver function tests
• Slit-lamp examination for Kayser-Fleischer rings
• Basal 24-hour urinary copper
• Genetic testing if mutations are known in the index case 1, 2

Common Pitfalls and Caveats

• No single test is sufficient for diagnosis or exclusion of Wilson's disease 1
• Urinary copper excretion may overlap with other liver diseases, particularly autoimmune hepatitis 1
• Wilson's disease should be considered in any patient between ages 3-55 years with liver abnormalities of uncertain cause 2
• Wilson's disease must be excluded in any patient with unexplained liver disease along with neurological or neuropsychiatric disorder 2
• Patients in the pediatric age bracket who present with autoimmune hepatitis should be investigated for Wilson's disease 2
• Adult patients with atypical autoimmune hepatitis or who respond poorly to standard corticosteroid therapy should also be investigated for Wilson's disease 2

Early diagnosis and treatment are essential for preventing irreversible organ damage and improving long-term outcomes in terms of morbidity, mortality, and quality of life 3.