Relative exchangeable copper, a high-quality biomarker for differentiation of Traditional Chinese Medicine syndrome in Wilson's disease.

Objective: To investigate the value of relative exchangeable copper (REC) in diagnosing Wilson's disease (WD) and to determine its significance in the differentiation of Traditional Chinese Medicine (TCM) syndrome.

Methods: A total of 78 patients with WD were recruited on the same day of the medical visit, and among them, 32 were suffering from non-WD (N-WD) and 37 were heterozygous ATP7B carriers (HC) enrolled as controls. Molecular genetic testing was performed for diagnosing WD and HC. Additionally, REC levels in different TCM syndromes were investigated. The correlation between REC and serum ceruloplasmin (Cp), serum copper oxidase (CO), and 24-h urinary copper was analyzed using the Global Assessment Scale and Unified Wilson's Disease Rating Scale and the significance of REC in WD diagnosis was investigated. Resting-state functional magnetic resonance imaging was used to assess the clinical symptoms of WD and analyze its severity in different TCM syndromes.

Results: REC determination helped in significantly distinguishing patients with N-WD or HC from those with WD with a cut-off of 21.15%. Furthermore, the comparative analysis of REC ratios among different TCM syndromes showed markedly high REC levels in the dampness-heat internal accumulation syndrome group. Additionally, the seed-based functional connectivity value from the putamen to the cerebellum was significantly correlated with TCM syndromes.

Conclusion: REC level is a high-quality biomarker for diagnosing WD that effectively reflects disease severity and plays an essential role in deciding on treatment strategies and prognosis. Furthermore, REC levels are closely related to TCM syndromes in WD; thus, it is a potential objective quantitative indicator for distinguishing TCM syndromes in WD.