Plasma zinc concentrations are decreased in patients on hemodialysis; zinc supplementation increases hemoglobin levels and reduces erythropoietin-stimulating agent treatments. However, inappropriate zinc supplementation causes copper deficiency. This review discusses the roles of zinc and copper throughout erythropoiesis; it also describes erythropoiesis-stimulating nutritional therapy that avoids copper deficiency, while providing safe zinc supplementation. In early erythropoiesis, erythropoietin regulates erythrocyte precursor proliferation and survival via zinc finger transcription factors. Mature blood cell formation and functional activation are regulated by zinc-mediated hormones, vitamins, and growth peptides. Zinc antagonizes the uptake of divalent cations (e.g., iron and copper) in erythrocyte precursors. Copper is required for iron transfer from cells to blood, ensuring dietary iron absorption and systemic iron distribution. In patients with copper deficiency, copper supplementation is initially performed, followed by zinc supplementation to manage hypozincemia. Serum zinc and copper measurements are needed at 2- to 3-month intervals during zinc supplementation to prevent copper deficiency.

Although it is well-known that plasma glucose concentration ((G)p) decreases during hemodialysis, the precise mechanism underlying this decrease has not yet been fully elucidated. The aim of the present study was to investigate the mechanism underlying hemodialysis-induced decrease (HID) in (G)p during the dialysis in vivo or in vitro. Using high CO2/ HCO3- dialysate, we measured (G)p by a hexose kinase method ((G)pHK) and concentrations of electrolytes, as well as pH, PCO2 and PO2 for both plasma and dialysate samples at pre- and postdialyzer sites obtained from hemodialysis patients with nondiabetic chronic renal failure (CRF). Furthermore, we studied the effect of PCO2 and acetazolamide (ACZ) on the changes in (G)pHK during the dialysis in vitro. After the first dialysis of CRF patients, the (G)pHK decreased from 118.3 +/- 18.0 to 98.6 +/- 5.7 mg/dl (p < 0.05), the latter value being significantly lower than glucose concentration in dialysate samples (approximately 105 mg/dl) at predialyzer sites. In the experiments of blood samples from healthy volunteers, (G)pHK decreased significantly after elevating or lowering CO2 level in the dialysates. In contrast, when the difference in PCO2 between the blood and dialysate was reduced, the HID in (G)pHK was abolished during hemodialysis. The addition of 10(-4) M ACZ to the blood samples completely prevented the development of HID in (G)pHK caused by the perfusion of high or low CO2/HCO3- dialysates. During hemodialysis using high CO2/HCO3- dialysate, the HID in (G)p results from the diffusion of glucose from plasma into erythrocytes, probably due to the consumption of glucose resulting from the accelerated anaerobic metabolism induced by the changes in the cytoplasmic pH of erythrocytes.

A key component of the etiology of leg cramping during hemodialysis sessions is alkalosis, which induces hypocalcemia and the release of calcium ions from the sarcoplasmic reticulum. Alkalosis is cau...

Patients undergoing hemodialysis often require zinc supplementation owing to hypozincemia, which may reduce serum copper concentrations. However, hypoxia-inducible factor–prolyl hydroxylase inhibitors (HIF-PHIs), which are used to treat renal anemia, have been reported to increase serum copper. Therefore, this study investigates the effectiveness of a combination of HIF-PHIs and zinc for the stabilization of serum copper and zinc concentrations during zinc supplementation for patients undergoing hemodialysis with renal anemia and hypozincemia. The serum zinc and copper concentrations were retrospectively compared over an 8-month period in 20 patients being administered roxadustat (an HIF-PHI) and 20 controls. The changes in concentrations were tracked in participants taking roxadustat who initiated or increased zinc supplementation. The serum zinc concentrations of the participants were significantly higher (p < 0.001) during zinc supplementation, regardless of roxadustat administration. Post-roxadustat, the serum copper concentrations were significantly higher than those pre-roxadustat or in non-roxadustat-treated participants, irrespective of zinc supplementation (p < 0.005). Even post-roxadustat, the serum copper concentrations were significantly lower, with no increase during zinc supplementation (p < 0.040). When zinc supplementation was initiated or increased in participants taking roxadustat, copper and zinc concentrations were normalized. Thus, combining zinc supplementation with roxadustat prevents both an excessive increase in serum copper and a decrease in serum zinc.

Since zinc is involved in many aspects of the hematopoietic process, zinc supplementation can reduce erythropoiesis-stimulating agents (ESAs) in patients undergoing hemodialysis. However, it remains unclear whether hypoxia-inducible factor–prolyl hydroxylase inhibitors (HIF-PHIs) have similar reduction effects. HIF-PHI stabilizes HIF, which promotes hematopoiesis, although HIF-1α levels are downregulated by zinc. This study aimed to investigate the effect of zinc supplementation on the hematopoietic effect of HIF-PHI in patients undergoing hemodialysis. Thirty patients undergoing maintenance hemodialysis who underwent periods of treatment with roxadustat or darbepoetin alfa during the past 3 years were retrospectively observed. Participants who underwent periods with and without zinc supplementation were selected, with nine treated with darbepoetin alfa and nine treated with roxadustat. Similarly to the ESA responsiveness index (ERI), the hematopoietic effect of zinc supplementation was determined by the HIF-PHI responsiveness index (HRI), which was calculated by dividing the HIF-PHI dose (mg/week) by the patient’s dry weight (kg) and hemoglobin level (g/L). Zinc supplementation significantly increased ERI (p < 0.05), but no significant change was observed (p = 0.931) in HRI. Although zinc supplementation did not significantly affect HRI, adequate zinc supplementation is required to alleviate concerns such as vascular calcification and increased serum copper during the use of HIF-PHI.