Analysis of tissue copper levels as a reliable diagnostic tool in paediatric liver disease

Elevated tissue copper levels are a useful diagnostic tool for the diagnosis of Wilson's disease (WD). However, the exact cut-off level for diagnosis is widely disputed, and elevated hepatic copper levels have been demonstrated in other liver diseases. This study, therefore, aims to evaluate the diagnostic accuracy of tissue copper levels derived from paediatric liver biopsies. Copper measurements including liver tissue copper, serum ceruloplasmin, and 24-h urinary copper were derived from electronic patient records and retrospectively analysed in children ≤ 18 years old with paediatric liver disease. Data was derived from children who attended for liver biopsy between June 2012 and October 2021. Mann-Whitney U tests were performed to test the difference between tissue copper in those with WD and non-Wilson's liver disease (NWLD). A total of 98 children were included in the final analyses. Those with WD had a significantly higher tissue copper level than NWLD (p < 0.0001). Only one of 23 children with untreated WD had a tissue copper level < 250 µg/g. Thirty-nine percent of people with WD were identified as having steatosis compared to 25% of the NWLD. Excluding one person, all those in the NWLD group with steatosis had metabolic dysfunction-associated steatotic liver disease. Conclusion: The cut-off level of ≥ 250 µg/g tissue copper may be reliably used to predict WD in children. The variables, low ceruloplasmin and presence of steatosis, should be used to come to a more reliable conclusion in children with tissue copper levels < 250 μg/g. The median tissue copper level in NWLD was < 250 μg/g. However, the use of tissue copper level alone to diagnose WD is precarious; thus, it should be used in combination with histopathology and biochemistry. What Is Known: • ⁠Elevated tissue copper levels is not exclusive to Wilson's disease and exists in other paediatric liver diseases. • ⁠The cut off level of ≥ 250 μg/g hepatic tissue copper has been conventionally recognised to aid Wilsons disease diagnosis, but remains disputed. What Is New: • ⁠Children with Wilson's disease have significantly higher tissue copper than those with non-Wilson's liver diseases. • ⁠The cut off level of ≥ 250 μg/g hepatic tissue copper should be used with other recognised parameters such as ceruloplasmin and urinary copper to aid diagnosis.