Serum copper, zinc levels linked to kidney function status

Increased serum copper levels are associated with higher albumin-to-creatinine ratio (ACR), while an inverse relationship exists between serum zinc and reduced estimated glomerular filtration rate (eGFR), reports a recent study.

To determine the role of trace elements such as copper and zinc in chronic kidney disease, the authors examined the association of serum copper and zinc with kidney function status, as well as explored possible effect modifiers in the general population. They analysed data from 5,353 National Health and Nutrition Examination Survey participants, aged 18‒80 years, from 2011 to 2016.

The following kidney outcomes were then assessed: reduced eGFR <60 mL/min/1.73 m² and increased urinary ACR ≥30 mg/g.

Serum copper was significantly associated with urinary ACR (odds ratio [OR], 1.04, 95 percent confidence interval [CI], 1.00‒1.07). After adjusting for confounders, serum copper levels of 18.0 μmol/L (median) or higher (reference level <18.0 μmol/L) significantly correlated with higher urinary ACR (OR, 1.67, 95 percent CI, 1.21‒2.31).

On the other hand, serum zinc was inversely associated with reduced eGFR (OR, 0.89, 95 percent CI, 0.81‒0.99). Serum zinc level >12.3 μmol/L (median) correlated with a lower prevalence of reduced eGFR (OR, 0.65, 95 percent CI, 0.16‒0.60).

Stratified analysis further revealed more significant associations between serum copper and increased urinary ACR risk among individuals with serum albumin >43 g/L or systolic blood pressure >120 mm Hg based on different risk factors.

“Our findings suggest that the reference levels of serum copper and zinc levels in healthy individuals may be different from current understanding,” the authors said. “If further studies substantiate the same, the results will be a useful guide for designing future clinical trials and nutritional guidelines.”