Background/Aim: Hepcidin could be one of the most important regulators for iron metabolism in patients on maintenance hemodialysis (MHD). The factors affecting serum hepcidin levels were evaluated among indexes of anemia, iron metabolism, or inflammation, as well as the dose of erythropoietin. Methods: 198 MHD patients treated with recombinant human erythropoietin were recruited and serum hepcidin-25 levels were specifically measured by liquid chromatography tandem mass spectrometry. Results: In multivariate analysis, only transferrin and ferritin were selected as significant predictors of hepcidin in all patients. In the selected patients with highly sensitive C-reactive protein of >0.3 mg/dl, however, ferritin as well as the IL-6 level were found to be significant predictors for serum hepcidin. The serum ferritin/hepcidin ratio was very similar among MHD and healthy volunteers, suggesting that uremic conditions do not affect the ratio. Serum hepcidin levels decreased by only 27% after a single hemodialysis session, but returned to basal levels 1 h after and remained so until the next hemodialysis session. Conclusions: In the absence of apparent inflammation, the serum hepcidin level could be exclusively associated with ferritin in MHD patients and was independent of inflammatory cytokines. Only in the presence of microinflammation, however, might IL-6 also affect hepcidin expression.

Serum levels of both hepcidin and TNF-α are independently associated with arterial stiffness in MHD patients, suggesting that microinflammation and iron metabolism might affect the integrity of arterial walls.

Background/Aims: Mortality in end-stage renal disease patients with dialysis remains high. A high percentage of dialysis patients display signs of chronic microinflammation. To clarify whether microinflammation is involved in the high incidence of poor prognosis in dialysis patients, we investigated the association of inflammatory markers with mortality in a prospective observational cohort study. Methods: 120 patients undergoing hemodialysis were enrolled. Baseline cross-sectional analysis of the relationship between inflammatory markers [interleukin-6 (IL-6), tumor necrosis factor-α and high-sensitivity C-reactive protein] and other factors, along with a survival analysis for death, were performed. All subjects were divided into 2 groups according to the median value of IL-6. Results: The mortality rate was significantly higher in the high (20.0%) compared with the low IL-6 group (3.3%, p = 0.0046). Receiver-operating characteristic curves indicated high mortality to be closely associated with a high IL-6 level rather than tumor necrosis factor-α. In stepwise multiple regression analyses, age, phosphorus and high-sensitivity C-reactive protein were independent predictors of IL-6 (R² = 0.466, p < 0.0001). Conclusions: These data clearly show that plasma IL-6 is a powerful predictor of all-cause mortality in dialysis patients.

Hepcidin has been established as a central regulator of iron metabolism. In most patients with chronic kidney disease (CKD), serum hepcidin levels are relatively high, favoring iron sequestration in several cell types and organs and thereby leading to iron-related complications. In the absence of overt inflammation, serum hepcidin has been found to be most closely associated with serum ferritin in healthy subjects and in CKD patients. Intestinal iron absorption is tightly regulated by both iron stores and hepcidin. The expression of the mammalian iron exporter, ferroportin (FPN), limits the growth of intracellular bacteria by depleting cytosolic iron. An upregulation of hepcidin could diminish FPN and favor bacterial growth. Of note, in patients with hyperferritinemia impaired hepcidin expression caused by a mutation in the hemochromatosis gene associates with an attenuation of atherosclerosis. Thus, hepcidin might accelerate atherosclerosis by preventing iron exit from macrophages or other cells in the arterial wall. High hepcidin levels have also been found to be linked to good erythropoiesis-stimulating agents (ESAs) response, in conjunction with the strong hepcidin-ferritin correlation. Finally, hepcidin may also play a significant role by itself in the pathogenesis of CKD complications associated with disturbed iron metabolism, i.e. unrelated to ESA hyporesponsiveness, such as bacterial infections and atherosclerosis.

Previously, dialysate contained small amounts of acetate as an alkaline buffer. Recently, acetate-free dialysate (A[-]D) has been available. We evaluated the clinical effect of A(-)D over acetate-containing dialysate (A(+)D) on acid-base balance, anemia, and nutritional status in maintenance hemodialysis (MHD) patients. Twenty-nine patients on MHD were treated with A(+)D for 4 months (first A(+)D), switched to A(-)D for 4 months, and returned to A(+)D for the next 4-month period (second A(+)D). Metabolic acidosis: Serum bicarbonate (HCO3(-) ) levels did not change in patients with normal HCO3(-) levels (≥20 mEq/L) throughout the study. Meanwhile, in patients with initially low HCO3(-) levels, it was significantly increased during the A(-)D period only. Anemia: In patients with target hemoglobin (Hb) ≥10 g/dL, Hb levels were maintained during the study period, even if the dose of erythropoiesis-stimulating agents (ESAs) decreased. In patients with low Hb levels, it was significantly increased in the A(-)D period without increasing ESA or iron doses. Nutritional Condition: In patients with normal albumin levels (≥3.8 g/dL), albumin did not change throughout the study period. However, in patients with lower albumin levels, it was significantly increased during the A(-)D period. These improvements in metabolic acidosis, anemia, and nutrition in the A(-)D period completely dissipated during the second A(+)D period. Hemodialysis (HD) with A(-)D may improve a patient's clinical status with intractable metabolic acidosis, hyporesponsiveness to ESA, and malnutrition that were not normalized in HD with A(+)D.