The Role of Zinc and Copper in Anemia and Erythropoietin Responsiveness in Patients on Hemodialysis and Peritoneal Dialysis

Abstract

Introduction: Imbalance in copper (Cu) and zinc (Zn) homeostasis is a frequent finding in patients undergoing dialysis. These patients have higher serum Cu and lower serum Zn levels compared to controls. This study is designed to investigate the relationship between blood Cu and Zn levels and Cu/Zn ratio and, ESA (erythropoietin stimulating agent) dosage, erythropoietin responsiveness and anemia in dialysis patients. Methods: Clinical and demographic data for 151 participants (men=79) with a median dialysis vintage of 69.7 months [101 on Hemodialysis (HD), 50 on Peritoneal Dialysis (PD)] and mean age of 56.25±15.6 years was collected in November 2022. Zn and Cu levels were measured with atomic absorption. Erythropoietin responsiveness was evaluated by the erythropoietin resistance index (ERI) and ESA dosing. Results: In HD patients, mean serum Zn and Cu levels were 61.33 ± 15.77 μg/dL and 95.1 ± 21.1 µg/dL, respectively, with a Cu/Zn ratio of 1.58 ± 0.69. In PD patients, mean serum Zn and Cu levels were 54.8 ± 10.3 µg/dL and 97 ± 20.2 µg/dL, respectively, with a Cu/Zn ratio of 1.72 ± 0.55. In Spearman analyses serum Cu was negatively correlated with hemoglobin (p=0.018), serum iron (p=0.03), transferrin saturation (p=0.019), and iron supplementation (p <0.01) in the HD patient group. Serum Cu was found to be positively correlated with erythropoietin (EPO) dosage (p=0.03), ERI (p=0.04), high sensitive C reactive protein (hsCRP) (p=0.01), and Kt/V (p=0.033). Cu/Zn ratio was positively correlated with EPO dosage (p=0.043), ERI (p=0.051) and hsCRP (p=0.015). Conversely, it was negatively correlated with iron supplementation (p=0.014) and serum albumin levels (p=0.049). Serum Zn levels was solely correlated with albumin level (p=0.039). In PD, patient’s serum Cu level was correlated positively with hsCRP (p=0.036); serum Zn levels correlated positively (p=0.01), and Cu/Zn ratio was correlated negatively with albumin (p=0.042). Conclusion: This study has shown a possible association between both serum Cu and Cu/Zn ratio, ESA dosage and hsCRP in HD patients.