In Wilson's disease, the Kayser-Fleischer ring results from copper deposition in Descemet's membrane. However, K-F rings can be absent in patients presenting with Wilson's liver disease alone. Which diagnostic test has highest sensitivity when K-F rings are absent?
- A Serum ceruloplasmin <0.1 g/L
- B 24-hour urinary copper >100 μg/day
- C Liver copper >250 μg/g dry weight on biopsy ✓
- D Serum copper >200 μg/dL
Explanation
Liver copper quantification >250 μg/g dry weight (by ICP-MS on biopsy) has the highest sensitivity (~86%) for Wilson's disease, especially when K-F rings are absent (absent in 50% of hepatic presentations). Ceruloplasmin can be falsely elevated (acute phase reactant) or falsely low in other liver diseases. The Leipzig scoring system for Wilson's disease uses K-F rings, neuropsychiatric symptoms, Coombs-negative haemolytic anaemia, ceruloplasmin, 24-hour urinary copper, and liver copper. A 24-hour urinary copper >100 μg after D-penicillamine challenge also supports diagnosis.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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