A 19-year-old woman is investigated for a combination of psychiatric symptoms (lability, psychosis), liver disease (ALT 320 U/L), haemolytic anaemia (Coombs-negative), and a golden-brown ring at the corneal periphery on slit-lamp examination. Serum ceruloplasmin is 8 mg/dL. What is the MOST specific biochemical test to confirm the diagnosis?
- A Liver copper content >250 μg/g dry weight on biopsy ✓
- B 24-hour urine copper after D-penicillamine challenge
- C Serum copper elevated above 150 μg/dL
- D ATP7B gene sequencing showing compound heterozygosity
Explanation
This is Wilson's disease (autosomal recessive copper metabolism disorder due to ATP7B mutation). The most specific diagnostic test is liver copper quantification on biopsy showing >250 μg/g dry weight. Low ceruloplasmin (<20 mg/dL), Kayser-Fleischer rings, and neuropsychiatric features are supportive. The Leipzig scoring system incorporates these. 24-hour urine copper >100 μg/day (or >1600 μg/day post-penicillamine challenge in children) is highly sensitive but less specific. Gene sequencing confirms mutation but has limited diagnostic role in compound heterozygotes with over 500 known mutations.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.