Usefulness of penicillamine-stimulated urinary copper excretion in the diagnosis of adult Wilson's disease.

Objective: Diagnosis of Wilson's disease (WD) is reliant on liver biopsy (LB) and measurement of hepatic copper. The aim of this study was to determine the usefulness of penicillamine-stimulated urinary copper excretion (PS-UCE), a non-invasive diagnostic test, for the diagnosis of WD in adults.

Material And Methods: In this prospective study of patients with suspected WD, total serum copper, ceruloplasmin, basal 24-h UCE and PS-UCE levels were measured. LB with copper determination was performed in those patients with persistent hypertransaminasemia and low ceruloplasmin or basal UCE > 40 microg/24 h. Diagnosis was established if the ceruloplasmin level was found to be < 20 mg/dl and hepatic copper > 250 microg/g. Results. A total of 115 patients were studied; LB was performed in 43, and WD was diagnosed in 6 (13.9%). Significant differences between WD and non-WD patients were found for basal UCE (WD: median 134.3 microg/24 h versus non-WD: median 19.0 microg/24 h (p < 0.05)) and PS-UCE (WD: median 1284.0 microg/24 h versus non-WD: median 776.0 microg/24 h; p < 0.01). In the ROC (receiver-operated curve) analysis, PS-UCE was the best discriminant between WD and non-WD (area under the curve (AUC) = 0.911, best cut-off point 1057 microg/24 h, 100% sensitivity, 82.3% specificity).

Conclusions: PS-UCE is probably a useful non-invasive test in the diagnosis of WD, improving the selection of patients for diagnostic liver biopsy. Patients with PS-UCE under 1057 microg/24 h only rarely will suffer from WD and are unlikely to benefit from LB.