Copper levels in patients undergoing peritoneal dialysis

Abstract Background Copper is an essential trace element. As copper is widely available in the diet, European best practice guidelines do not recommend routine supplementation for individuals with kidney conditions, although some medicines routinely prescribed may reduce absorption. As more patients who are frail and have co-morbidities are treated by peritoneal dialysis, we wished to determine whether supplements are required. Methods Serum copper was measured in 550 patients undergoing peritoneal dialysis, with a mean age of 59 ± 16 years, 61% male patients, 45% with diabetes and a median dialysis vintage of 2 years (2–3 years). We investigated variables associated with serum copper in patients undergoing peritoneal dialysis. Results The mean serum copper was 17.3 ± 3.78 µmol/L, which was normal in 86.3%, low in 2.4% and high in 11.3% of the patients. Serum copper was associated with C-reactive protein (CRP) ( r = 0.36), zinc ( r = 0.15) and skeletal muscle mass (SMM; r = −0.15), with p < 0.001. On adjusted multiple linear regression analysis, the following were found: CRP (beta coefficient ( β ) 0.05, 95% confidence intervals (CI) 0.04–0.06); zinc ( β 0.27, 95% CI 0.13–0.14); both p < 0.001; and lower SMM ( β −0.06, 95% CI −0.12 to −0.004), p = 0.035. Phosphate binder prescription, particularly calcium-containing binders, had lower serum copper (mean difference 0.98 µmol/L, 95% CI 0.35–1.61) compared with other binders, p = 0.002. Conclusions Most patients undergoing peritoneal dialysis (PD) had normal copper levels, but levels were higher in patients with inflammation and higher zinc and lower in patients prescribed calcium-containing phosphate binders.