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 μmol/L) was significantly higher in group 1 (mean 2.2±0.7 μmol/L) compared to the other three groups: group 2=0.9±0.4 μmol/L, group 3=1.2±0.4 μmol/L, group 4=1.1±0.3 μmol/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.