Relative exchangeable copper: a valuable tool for the diagnosis of Wilson disease.

Background & Aims: Measuring of the relative exchangeable copper seems to be a promising tool for the diagnosis of Wilson disease. The aim of our study is to determine the performance of REC for the diagnosis of Wilson disease in a population of patients with chronic liver diseases. Methods: Measuring of exchangeable serum copper levels and relative exchangeable copper was performed in a group of Wilson disease patients at diagnosis or at clinical deterioration because of non-compliance (group 1, n=9), a group of stable WD patients (group 2, n=40), and two groups of patients (adult and paediatric) followed for non-Wilsonian liver diseases (group 3, n=103 and group 4, n=49 respectively). Results: Exchangeable serum copper (N: 0.6-1.1 mu mol/L) was significantly higher in group 1 (mean 2.2 +/- 0.7 mu mol/L) compared to the other three groups: group 2=0.9 +/- 0.4 mu mol/L, group 3=1.2 +/- 0.4 mu mol/L, group 4=1.1 +/- 0.3 mu mol/L (P<0.05). Relative exchangeable copper was significantly higher in Wilson disease patients group 1 and 2 (mean 52.6% and 43.8%) compared to patients suffering from other liver diseases (mean 7.1% and 5.9%) (P<0.05). Conclusions: Our study confirms that the determination of relative exchangeable copper is a highly valuable tool for the diagnosis of Wilson disease.