Labile Bound Copper (LBC) and Total Serum Copper Concentrations in Newborns and Infants

Effective markers for early detection of Wilson disease are of interest. Recently, a labile bound copper assay has been developed for the evaluation of copper disorders, which in concert with total copper concentrations can effectively detect Wilson disease in adults. Newborn labile bound copper (LBC) concentrations may also resemble those observed in adult patients with Wilson disease, as newborns exhibit low total copper concentrations and limited ceruloplasmin production. The primary goal of this study was to investigate LBC and total copper concentrations in newborns (0-4 weeks of age) and infants (5-29 weeks of age) and to compare them to those seen in adult patients with Wilson disease. Associations between LBC, LBC fraction, and total copper versus bilirubin concentrations in newborns were also investigated. Serum samples originally measured for bilirubin concentrations were analyzed for labile bound copper, labile bound copper fraction, and total serum copper by inductively coupled plasma mass spectrometry. Nearly 35% of newborns had labile bound copper fraction values that were above the adult reference interval cutoff, resembling values seen in adults with Wilson disease. Labile bound copper fraction values in pre-term newborns were higher than in full-term newborns, and pre-term newborns had lower total copper concentrations compared to full-term newborns. Finally, after adjusting for age, total copper concentrations in both newborns and infants were negatively correlated with both total bilirubin and unconjugated bilirubin. While the labile bound copper assay may not be suitable for evaluating newborns for Wilson disease, it may be a useful tool to assess copper metabolism.