The relationship between serum copper and ceruloplasmin in routine chnical practice

Introduction: The biochemical assessment of copper status is not easy when investigating deficient and excess states. Most clinicians request copper and ceruloplasmin and assume that the results provided by their local laboratory are comparable with data in the literature. Aims and methods: We decided to obtain paired copper and ceruloplasmin values retrospectively from the laboratory information systems from three different hospital laboratories to see how the relationships compared. Descriptive statistics and the relationship between caerulo-plasmin and copper were obtained. Results: Our data shows differences in the relationship (slope, intercept and correlation co-efficient) between copper and ceruloplasmin; this is especially the case at the clinical cut-off of a ceruloplasmin concentration of 200 mg/l. Conclusion: Differing methods or populations may be contributing to the differences between the data sets. We therefore recommend that local cut-offs are derived for the investigation of copper deficiency and excess states.