Measurement of urinary copper excretion after 48-h d-penicillamine cessation as a compliance assessment in Wilson's disease.

Treatment of Wilson's disease (WD) with anti-copper agents is effective in most compliant patients. During long-term treatment with chelating agents, a two-day interruption of the treatment should result in normal urinary copper concentrations (<50 μg/dl). The aim of this study was to establish the usefulness of this method as a compliance assessment in these patients. We examined consecutive patients treated with d-penicillamine (DPA) undergoing routine follow-up studies at our center. We performed 24-h urinary copper excretion analysis 48 h after interruption of chelating therapy. Thirty-two patients were enrolled. After DPA cessation, normalization of copper excretion was observed in 91% of reportedly compliant patients. The specificity and sensitivity values of this test were 87% and 77%, respectively. Measurement of 24-h urinary copper excretion after a 48-h interruption of DPA therapy in patients with WD is a reliable method for confirming patients' compliance.