Investigations in Wilson Disease

Copper metabolism and consequences of ATP7B mutation. Failure of biliary copper excretion and ceruloplasmin loading results in hepatotoxic copper accumulation and systemic copper release. (Robbins & Kumar Basic Pathology)

1. Slit-Lamp Examination (Kayser-Fleischer Rings)

• Present in ~98% of patients with neurological WD and ~80% of all WD cases
• Present in only ~50% of patients with isolated hepatic WD - so absence does NOT exclude the diagnosis in liver-only presentations
• Absent KF ring + normal ceruloplasmin together virtually excludes WD in a patient with neurological/psychiatric symptoms
• Must be examined by slit lamp - cannot be reliably seen with the naked eye

"A KF ring is present in 98% of patients with neurological disease and in 80% of all cases of WD." - Bradley and Daroff's Neurology in Clinical Practice

2. Serum Ceruloplasmin

• Low ceruloplasmin is not specific - also seen in severe liver disease of any cause, nephrotic syndrome, protein-losing enteropathy, malnutrition
• Ceruloplasmin can be falsely normal or elevated in WD because it is an acute-phase reactant - pregnancy, infection, and inflammation can raise it
• For patients with liver dysfunction: ceruloplasmin is generally <20 mg/dL

3. 24-Hour Urinary Copper Excretion

• In fulminant WD: urinary copper is markedly elevated
• False positives: any cholestatic liver disease can raise urine copper
• D-penicillamine challenge: in children, urine copper >25 μmol/24h after 500 mg D-penicillamine is given twice (total 1g over 12h) is suggestive (2 points in Leipzig score)

4. Serum Copper

• Total serum copper is usually low in WD (because ceruloplasmin-bound copper is reduced)
• However, in acute liver failure from WD, massive copper release from the necrotic liver causes serum copper to be strikingly elevated
• Non-ceruloplasmin-bound (free) copper is elevated in most WD patients and is a sensitive indicator, but not widely available in routine labs

5. Liver Biopsy with Quantitative Copper

• Sample must be collected in a trace element-free container on a fresh specimen
• Histochemical stains (rhodanine, rubeanic acid) for copper may be negative even with massive accumulation, and may be positive in other cholestatic conditions - they should NOT be relied upon for diagnosis
• Histological features of WD range from steatosis and focal necrosis to chronic hepatitis with Mallory bodies, to cirrhosis
• Liver biopsy may be contraindicated in fulminant WD due to coagulopathy

"There is no correlation between histochemical staining of copper and quantitative copper measurements of liver biopsy samples in Wilson disease. Therefore, these histochemical stains should not be used to establish or exclude this diagnosis." - Yamada's Textbook of Gastroenterology

6. Special Serum Ratios (for Acute Liver Failure / Fulminant WD)

7. Blood and Haematological Tests

• Coombs-negative (DAT-negative) haemolytic anaemia: in acute/fulminant WD, massive copper release from the necrotic liver causes direct erythrocyte lysis - this is a hallmark finding (1 point, Leipzig)
• Liver function tests: elevated transaminases, variable bilirubin (conjugated then unconjugated if haemolysis present), low albumin in advanced disease
• Serum uric acid: characteristically low in WD due to Fanconi-type renal tubular losses - a valuable clue
• Coagulation screen: PT/INR prolonged in severe hepatic involvement
• FBC: anaemia (haemolytic or from chronic disease), thrombocytopenia if hypersplenism/cirrhosis

8. Genetic Testing (ATP7B Mutation Analysis)

• Over 300 pathogenic mutations identified; most are small deletions or missense mutations
• Most common mutation: His1069Gln (up to 40% of cases in some ethnic populations)
• Absence of mutations does NOT exclude WD when clinical suspicion is high - testing is considered "uninformative" in that setting
• Most useful for family screening of first-degree relatives once a proband is identified

9. Neuroimaging (MRI Brain)

• MRI shows T2 hyperintensity in the basal ganglia (especially putamen), thalamus, midbrain, pons, cerebellum
• "Face of the giant panda" sign on axial MRI - hyperintensity in the tegmentum with preserved red nuclei and substantia nigra
• Cerebral and cerebellar atrophy is common
• Not diagnostic alone, but supports the diagnosis in neurological WD

10. The Leipzig Scoring System

• ≥4: Wilson disease diagnosis confirmed
• 3: Further testing required
• ≤2: Wilson disease unlikely

Summary: Investigation Approach by Presentation

• Yamada's Textbook of Gastroenterology, 7th ed. (Chapter 94)
• Robbins & Kumar Basic Pathology
• Bradley and Daroff's Neurology in Clinical Practice
• Sleisenger and Fordtran's Gastrointestinal and Liver Disease