Association of copper exposure with prevalence of chronic kidney disease among a Chinese elderly population

BACKGROUND AND AIM: Metal exposures are suspected to associate with the risk of chronic kidney disease (CKD). Copper (Cu) is an essential yet toxic trace element in humans. Epidemiological evidence on the association of Cu exposure with CKD remains inconsistent. We aim to investigate the association of blood Cu and its co-exposure to other metals with CKD. METHODS: A cross-sectional study was conducted among 3,286 Chinese elderly adults in Zhejiang, China. The whole blood levels of Cu as well as other 10 metals were measured by inductively coupled plasma mass spectrometry (ICP-MS). CKD events were defined as the presence of albuminuria or <60 mL/min/1.73m2 estimated glomerular filtration rate (eGFR). Multivariable logistic regression and linear regression models were applied to assess the single-metal association of Cu with kidney function. The Bayesian kernel machine regression (BKMR) was used to estimate associations of the metal mixture with CKD. RESULTS: In the logistic models, we observed a positive dose-dependent association of blood Cu with CKD prevalence after adjusting for multiple covariates. Positive linear dose-response associations with blood Cu were also found for CKD and negative for eGFR. The positive association between blood Cu and CKD risk also observed in BKMR model and stronger at lower level of manganese (Mn). CONCLUSIONS: The whole blood level of Cu was remarkably associated with the prevalence of CKD and showed positive dose-response relationships in the elderly Chinese population. The toxicity of Cu on kidney function could be antagonized by the exposure of Mn. These findings have provided new clues of the potential roles of Cu in kidney health, and the needs to develop not only recommended intake but also safe limits for Cu. KEYWORDS: copper, chronic kidney disease, whole blood, BKMR analysis, manganese.