Does hepcidin affect erythropoiesis in hemodialysis patients?

Ziltivekimab for Treatment of Anemia of Inflammation in Patients on Hemodialysis: Results from a Phase 1/2 Multicenter, Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND

Patients with CKD who are on hemodialysis are hyporesponsive to erythropoiesis-stimulating agents (ESAs) because of anemia of inflammation. Interleukin-6 (IL-6) induced hepcidin expression is a key mediator of such inflammation.

METHODS

This phase 1/2, placebo-controlled trial assessed effects of ziltivekimab, a novel anti-IL-6 ligand antibody, in patients on hemodialysis with rs855791, a single nucleotide polymorphism of the TMPRSS6 gene that is hypothesized to heighten susceptibility to IL-6-mediated inflammatory effects. After a screening period documenting stable ESA and iron dosing, we randomized 61 patients with elevated IL-6 (≥4 pg/ml) to receive placebo or ziltivekimab (doses of 2, 6, or 20 mg), administered intravenously every 2 weeks for 12 weeks during hemodialysis. ESA dose adjustments were allowed after 4 weeks. We analyzed safety and effects on inflammation, iron metabolism, serum albumin, and anti-drug antibodies.

RESULTS

No patient experienced dose-limiting toxicity. Four patients (two each in the 6- and 20-mg cohorts) died of a treatment-emergent adverse event. Compared with patients receiving placebo, those receiving ziltivekimab experienced significantly greater reductions of high-sensitivity C-reactive protein, serum amyloid A, and fibrinogen from baseline to end of treatment. Median ESA usage decreased by 15,000, 15,000, or 33,000 IU/wk per patient in the 2-, 6-, and 20-mg ziltivekimab cohorts, respectively, compared with no change in the placebo group. We also noted significant dose responses for decreased ESA resistance index and increased serum iron, total iron binding capacity, transferrin saturation, and serum albumin.

CONCLUSIONS

Ziltivekimab significantly improved markers of inflammation, reduced ESA requirements, and increased serum albumin in patients on hemodialysis with inflammation and hyporesponsiveness to ESA therapy.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Study to Assess the Safety, Pharmacokinetics, and Pharmacodynamics of Multiple Doses of COR-001, NCT02868229.

Relationship between the serum levels of Vitamin D and inflammatory markers in ESRD patients

BACKGROUND AND AIM

In patients with End-stage renal disease (ESRD), 25-(OH)-Vitamin D3 deficiency is a common problem and also the inflammatory responses increase in these patients. The present study aims to evaluate the relation of 25-(OH)-Vitamin D3 with the indirect inflammatory markers in patients on hemodialysis (HD) and peritoneal dialysis (PD).

METHODS

This study was done by cross-sectional method on 85 ESRD patients receiving renal replacement therapy (RRT), from one geographical area. 64 patients on HD and 21 patients on PD who were matched for age and sex were studied. Serum level of 25-(OH) Vitamin D3 was measured in each patient. ESR, CRP and the other routine blood tests were measured as well.

RESULTS

The level of 25-OH Vitamin D3 was significantly lower in PD group in comparison to HD group (P: 0/0012, 2/70±0/10 vs 2/05±0/14). Platelet (195/40 ± 7/6 vs 265/52 ± 15/6, P: 0/001) and ESR (46/80 ± 6/89 vs 23/53 ± 1/96, P: 0/003) were significantly higher in PD group. Considering total population of the study (PD and HD), there was a significant association between ESR and serum level of 25-(OH)-Vitamin D3 (r: 0.26, P: 0.036) but no correlation was seen between 25-(OH)-Vitamin D3 and hemoglobin (Hb) or duration of dialysis. On the other hand, in patients on HD, multiple regression analysis revealed a significant relationship between duration of dialysis (P: 0.02), Hb (P: 0.01) and ESR (P: 0.001) with 25-(OH)-Vitamin D3 level. Moreover, there was a relationship between vitamin D3 levels and inflammatory markers as well.

CONCLUSIONS

The deficiency of 25-(OH)-Vitamin D3 was followed with increase of ESR as an inflammatory marker in patients on HD. Key words: Inflammation; 25-hydroxy vitamin D; Renal replacement; Dialysis.

Soluble transferrin receptor as a marker of erythropoiesis in patients undergoing high-flux hemodialysis

Anemia is a common complication in chronic kidney disease (CKD) patients receiving hemodialysis. The effect of high-flux dialysis (HFD) on anemia remains unclear. This prospective study aimed to evaluate the effect of HFD on anemia, and the potential of soluble transferrin receptor (sTfR) as a marker of iron status and erythropoiesis in CKD patients on hemodialysis. Forty patients, who switched from conventional low-flux dialysis to HFD for 12 months, were enrolled in this study. The levels of sTfR, hemoglobin (Hb), iron, and nutritional markers, as well as the dose of recombinant human erythropoietin (rhEPO) and use of chalybeate were determined at 0, 2, 6, and 12 months after starting HFD. HFD significantly increased the hemoglobin level and reduced sTfR level in CKD patients (p < 0.05). In addition, significant decreasing linear trends were observed for rhEPO dosage and chalybeate use (p < 0.05). The level of sTfR was positively correlated with the percentage of reticulocytes (RET%), rhEPO dose, and chalybeate use, while it was negatively correlated with Hb levels and total iron-binding capacity results (all p < 0.05). A univariate generalized estimating equation (GEE) model showed that the Hb level, RET%, rhEPO dose, and chalybeate use were the variables associated with sTfR levels. A multivariate GEE model showed that the time points when hemodialysis was performed were the variables associated significantly with sTfR levels. Overall, our findings suggest that HFD can effectively improve renal anemia in hemodialysis patients, and sTfR could be used as a marker of erythropoiesis in HFD patients.

Serum copper and ferroportin in monocytes of hemodialysis patients are both decreased but unassociated

PURPOSE

Disturbed iron homeostasis contributes to resistance to recombinant human erythropoietin (rHuEpo) in hemodialysis (HD) patients. Although increased hepcidin, which downregulates the iron exporter ferroportin, had been incriminated, such an association has not been confirmed. Albeit not universally accepted, it has been supported that in case of copper deficiency, decreased activity of multicopper oxidases induces endocytosis and degradation of ferroportin. Ferroportin in monocytes, serum copper, ceruloplasmin and markers of iron status were measured, and associations with rHuEpo resistance index (ERI) were evaluated.

METHODS

After a 4-week washout period from iron treatment, 34 HD patients and 20 healthy volunteers enrolled in the study. Ferroportin was assessed by means of Western blotting, copper colorimetrically, whereas ceruloplasmin with enzyme-linked immunosorbent assay. Hemoglobin, serum iron, ferritin and transferrin saturation (TSAT) were also measured.

RESULTS

Ferroportin in monocytes of HD patients was decreased. Serum copper, ceruloplasmin, iron and TSAT were decreased. No correlation between copper or ceruloplasmin and ferroportin was detected. ERI was negatively correlated with ferroportin and all the markers of iron adequacy, but not with copper or ceruloplasmin.

CONCLUSION

Although copper deficiency and decreased ferroportin are common in HD patients, copper might not play role in ferroportin level in monocytes and in iron metabolism in this population.

Regulation of Hepcidin-25 by Short- and Long-Acting rhEPO May Be Dependent on Ferritin and Predict the Response to rhEPO in Hemodialysis Patients

Background/Aims

We examined whether regulation of hepcidin-25 by short- or long-acting recombinant human erythropoietin (rhEPO) is dependent on ferritin and predicts the response to rhEPO in hemodialysis (HD) patients.

Methods

Two studies with rhEPO were performed in 9 HD patients with a 2-year interval. Serum hepcidin-25 was measured at 0-18 h after intravenous epoetin-β (EPO) or methoxy polyethylene glycol-epoetin-β (PEG-EPO) administration and on days 3-7 after PEG-EPO. Hemoglobin (Hb), serum ferritin, transferrin, C-reactive protein (CRP), and interleukin (IL)-6 were analyzed before hepcidin measurement and 6 months after rhEPO. Based on the serum ferritin levels before hepcidin measurement, the patients in the two studies with EPO or PEG-EPO were combined into low (11; serum ferritin of <15.0 ng/ml) and high ferritin groups (7; serum ferritin of ≥15.0 ng/ml). The response of hepcidin-25 to rhEPO and the effect of rhEPO on anemia were compared between the groups.

Results

The serum hepcidin-25 levels rose at 6-9 h and returned to the baseline at 18 h after EPO. They rose at 6-9 h, returned to the baseline at 18 h, and decreased on day 5-7 after PEG-EPO. Serum hepcidin-25 levels were low (<5.0 ng/ml) in the low ferritin group, but rose at 6-9 h after rhEPO in the high ferritin group. Serum transferrin levels were similar, and CRP and IL-6 were normal in both groups. Hb tended to increase in the low ferritin group, but it significantly decreased in the high ferritin group after rhEPO.

Conclusion

Regulation of hepcidin-25 by rhEPO may be dependent on ferritin, affecting the response to rhEPO in HD patients.

Effects of additional iron doses on hepcidin-25 level in hemodialysis patients without evident iron deficiency

BACKGROUND

Serum hepcidin-25 is not only a marker of iron stores, but also an acute phase reactant, and it could fluctuate in response to erythropoietic activity.

STUDY DESIGN

Prospective interventional, 3-months duration, investigating the influence of additional intravenous (IV) iron on hepcidin-25 in hemodialysis (HD) patients without obvious iron deficiency (ID).

SETTINGS AND PARTICIPANTS

Single HD unit, 41 patients.

MEASUREMENTS

Hepcidin-25 (ELISA method), ferritin, transferrin, transferrin saturation (TSAT), C-reactive protein and serum albumin--at baseline and assessment; hemoglobin, iron and darbepoetin doses--monthly.

INTERVENTION

Additional IV iron doses were administered, driven by hemoglobin trend: iron dose increased by 25 % for each 0.5 g/dL hemoglobin drop for baseline ferritin of 200-800 ng/mL. Iron was discontinued for stable hemoglobin or >13 g/dL. Darbepoetin doses were adjusted for 11 g/dL target hemoglobin.

RESULTS

At baseline, 21 % of patients had "optimal" iron status; none had "absolute" or "functional" ID, while 15 % had iron "overload." Hepcidin levels were 112.8 (95 % CI 105.3-121.8) ng/mL. Hemoglobin was within the target range. After 75 % augmentation in iron doses, hepcidin-25 decreased by 70 %. Transferrin increased, and TSAT and ferritin decreased. Prevalence of "functional" ID rose to 24 % and of iron "overload" declined to 0 %. Reversal of iron-restricted erythropoiesis was further sustained by unchanging hemoglobin and decrease in darbepoetin doses and darbepoetin resistance index. Reasonable associations between assessment versus baseline ratios for hepcidin-25 and transferrin (inverse), TSAT and ferritin (direct) were found. Despite the increased inflammation, decrease in transferrin and increase in ferritin ratios were independent predictors of hepcidin variability (model of logistic regression r (2) 0.34; p < 0.0001).

LIMITATIONS

Low number of participants, less diabetic nephropathy/vascular diseases than general dialyzed population, uncontrolled design, use of hepcidin-25 ELISA assay.

CONCLUSIONS

Activation of erythropoiesis by additional IV iron administration overcomes moderate inflammation in suppressing hepcidin-25. Thus, hepcidin-25 could be clinically useful to evaluate iron status in patients with renal anemia.

Potential effects of omega-3 fatty acids on anemia and inflammatory markers in maintenance hemodialysis patients

BACKGROUND

Anemia is a common complication among hemodialysis (HD) patients. Although intravenous iron and erythropoiesis-stimulating agents revolutionized anemia treatment, about 10% of HD patients show suboptimal response to these agents. Systemic inflammation and increased serum hepcidin level may contribute to this hyporesponsiveness. Considering the anti-inflammatory properties of omega-3 fatty acids, this study aimed to evaluate potential role of these fatty acids in improving anemia and inflammation of chronic HD patients.

METHODS

In this randomized, placebo-controlled trial, 54 adult patients with HD duration of at least 3 months were randomized to ingest 1800 mg of either omega-3 fatty acids or matching placebo per day for 4 months. Anemia parameters including blood hemoglobin, serum iron, transferrin saturation (TSAT), erythropoietin resistance index, and required dose of intravenous iron and erythropoietin, and serum concentrations of inflammatory/anti-inflammatory markers including interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-10, C-reactive protein (CRP), hepcidin, ferritin, intact parathyroid hormone (iPTH), and ratios of IL-10 to IL-6 and IL-10 to TNF-α were measured at baseline and after 4 months of the intervention.

RESULTS

45 subjects (25 in the omega-3 and 20 in the placebo group) completed the study. No significant changes were observed in blood hemoglobin, serum iron, TSAT, and required dose of intravenous iron in either within or between group comparisons. Additionally, erythropoietin resistance index as well as required dose of intravenous erythropoietin showed no significant change in the omega-3 group compared to the placebo group. Although a relative alleviation in inflammatory state appeared in the omega-3 group, the mean differences of inflammatory and anti-inflammatory markers between the two groups did not reach statistically significant level except for IL-10-to-IL-6 ratio and serum ferritin level which showed significant changes in favor of omega-3 treatment (P <0.001 and P = 0.003, respectively).

CONCLUSION

Omega-3 fatty acids relatively improved systemic inflammation of chronic HD patients without any prominent benefits on anemia. However, future well-designed studies on larger number of patients may determine utility of omega-3 fatty acids in HD patients with respect to inflammation and anemia.

Ferroportin in monocytes of hemodialysis patients and its associations with hepcidin, inflammation, markers of iron status and resistance to erythropoietin

PURPOSE

Disturbed iron homeostasis contributes to resistance to recombinant human erythropoietin (rHuEpo) in hemodialysis (HD) patients. Increased hepcidin, which downregulates the iron exporter ferroportin, has been incriminated. However, other factors also control ferroportin expression in mononuclear phagocyte system. Ferroportin in monocytes, as well as serum hepcidin, interleukin-6 (IL-6) and common markers of iron status were measured and correlations with rHuEpo resistance index (ERI) were evaluated.

METHODS

After a 4-week washout period from iron treatment, 34 HD patients and 20 healthy volunteers enrolled in the study. Ferroportin was assessed by means of western blotting, whereas hepcidin and IL-6 with enzyme-linked immunosorbent assay. Hemoglobin, serum iron, ferritin and transferrin saturation (TSAT) were also measured.

RESULTS

Ferroportin in monocytes of HD patients was decreased. Serum hepcidin and IL-6 were increased, whereas serum iron and TSAT were decreased. ERI was negatively correlated with ferroportin and all the markers of iron adequacy, but not with hepcidin.

CONCLUSION

Decreased ferroportin in monocytes of HD patients accompanies increased hepcidin, inflammation, decreased iron availability and is correlated with resistance to rHuEpo treatment.

Is hemojuvelin a possible new player in iron metabolism in hemodialysis patients?

Introduction

Hemojuvelin (HJV) is highly expressed in the liver, skeletal muscles, and heart, seems to play a role in iron absorption and release from cells, and has anti-inflammatory properties. Moreover, HJV plays an essential role in the regulation of hepcidin expression, specifically in the iron-sensing pathway. Hepcidin has emerged as a key regulator of iron homeostasis. In this study we tested for the first time the hypothesis that HJV is related to iron metabolism in hemodialysis (HD) patients.

Methods

Iron status, complete blood count, and serum creatinine, albumin, and lipids were assessed, using standard laboratory methods. Serum levels of soluble transferrin receptor (sTFR), high-sensitivity CRP, IL-6, hepcidin, and HJV were measured using commercially available kits.

Results

Serum HJV, hepcidin, ferritin, IL-6, hsCRP, and serum creatinine were significantly higher (all P < 0.001), whereas serum iron, sTFR, transferrin, hemoglobin, and erythrocyte count were significantly lower in HD patients, compared to healthy volunteers (all P < 0.001). In univariate analysis, HJV was strongly correlated (P < 0.001) with ferritin, transferrin saturation, and TIBC, as well as with hsCRP, hepcidin, Kt/V (P < 0.01) and residual renal function, the presence of diabetes, APKD, and coronary heart disease. Predictors of HJV level in multiple regression analysis were ferritin (beta value was 0.50, P = 0.00004) and transferrin saturation (beta value was 0.47, P = 0.0002), explaining 81% of the HJV variations.

Conclusions

Serum HJV is elevated in HD patients and related predominantly to kidney function and iron metabolism. However, HJV is probably not correlated to inflammation. HJV appears to be a new player in iron metabolism in these patients.

Soluble erythropoietin receptor contributes to erythropoietin resistance in end-stage renal disease

BACKGROUND

Erythropoietin is a growth factor commonly used to manage anemia in patients with chronic kidney disease. A significant clinical challenge is relative resistance to erythropoietin, which leads to use of successively higher erythropoietin doses, failure to achieve target hemoglobin levels, and increased risk of adverse outcomes. Erythropoietin acts through the erythropoietin receptor (EpoR) present in erythroblasts. Alternative mRNA splicing produces a soluble form of EpoR (sEpoR) found in human blood, however its role in anemia is not known.

METHODS AND FINDINGS

Using archived serum samples obtained from subjects with end stage kidney disease we show that sEpoR is detectable as a 27kDa protein in the serum of dialysis patients, and that higher serum sEpoR levels correlate with increased erythropoietin requirements. Soluble EpoR inhibits erythropoietin mediated signal transducer and activator of transcription 5 (Stat5) phosphorylation in cell lines expressing EpoR. Importantly, we demonstrate that serum from patients with elevated sEpoR levels blocks this phosphorylation in ex vivo studies. Finally, we show that sEpoR is increased in the supernatant of a human erythroleukaemia cell line when stimulated by inflammatory mediators such as interleukin-6 and tumor necrosis factor alpha implying a link between inflammation and erythropoietin resistance.

CONCLUSIONS

These observations suggest that sEpoR levels may contribute to erythropoietin resistance in end stage renal disease, and that sEpoR production may be mediated by pro-inflammatory cytokines.

Pro-hepcidin and iron metabolism parameters in multi-time blood donors

A high number of blood donations may cause iron depletion. The pathophysiology behind this process may involve hepcidin, a recently discovered peptide that acts by inhibiting iron absorption and promoting iron retention in reticuloendothelial macrophages. The aim of this study was to determine serum pro-hepcidin levels and iron metabolism parameters in multi-time blood donors. The study group consisted of 132 multi-time male blood donors and 25 healthy male volunteers (nondonors). Complete blood cell count and iron status including serum iron, ferritin, soluble transferrin receptor (sTfR), total iron binding capacity (TIBC), unsaturated iron binding capacity (UIBC), erythropoietin and pro-hepcidin (ELISA) were assessed. In blood donors, ferritin level drops markedly in relation to donation frequency (P < 0.001). In contrast, TIBC and UIBC levels increase progressively corresponding to annual donation frequency. Pro-hepcidin concentration increases significantly with the number of donations per year (P = 0.0290). In blood donors having donated blood with the highest frequency per year, pro-hepcidin levels were positively correlated with haemoglobin (R = 0.31, P < 0.05) and negatively with sTfR (R = -0.31, P < 0.05). Pro-hepcidin levels increase in relation to blood donation frequency per year. Longitudinal studies focusing on changes in serum hepcidin levels are required to address the question whether hepcidin may contribute to iron metabolism disturbances in multi-times blood donors.

Plasma hepcidin levels are elevated but responsive to erythropoietin therapy in renal disease

Hepcidin is a critical inhibitor of iron export from macrophages, enterocytes, and hepatocytes. Given that it is filtered and degraded by the kidney, its elevated levels in renal failure have been suggested to play a role in the disordered iron metabolism of uremia, including erythropoietin resistance. Here, we used a novel radioimmunoassay for hepcidin-25, the active form of the hormone, to measure its levels in renal disease. There was a significant diurnal variation of hepcidin and a strong correlation to ferritin levels in normal volunteers. In 44 patients with mild to moderate kidney disease, hepcidin levels were significantly elevated, positively correlated with ferritin but inversely correlated with the estimated glomerular filtration rate. In 94 stable hemodialysis patients, hepcidin levels were also significantly elevated, but this did not correlate with interleukin-6 levels, suggesting that increased hepcidin was not due to a general inflammatory state. Elevated hepcidin was associated with anemia, but, intriguingly, the erythropoietin dose was negatively correlated with hepcidin, suggesting that erythropoietin suppresses hepcidin levels. This was confirmed in 7 patients when hepcidin levels significantly decreased after initiation of erythropoietin treatment. Our results show that hepcidin is elevated in renal disease and suggest that higher hepcidin levels do not predict increased erythropoietin requirements.

Intravenous iron versus erythropoiesis-stimulating agents: friends or foes in treating chronic kidney disease anemia?

Patients with chronic kidney disease (CKD), especially those requiring maintenance hemodialysis treatments, may lose up to 3 g of iron each year because of frequent blood losses. Higher doses of erythropoiesis-stimulating agents (ESAs) may worsen iron depletion and lead to an increased platelet count (thrombocytosis), ESA hyporesponsiveness, and hemoglobin variability. Hence, ESA therapy requires concurrent iron supplementation. Traditional iron markers such as serum ferritin and transferrin saturation ratio (TSAT) (ie, serum iron divided by total iron-binding capacity [TIBC]), may be confounded by non-iron-related conditions. Whereas serum ferritin <200 ng/mL suggests iron deficiency in CKD patients, ferritin levels between 200 and 1,200 ng/mL may be related to inflammation, latent infections, malignancies, or liver disease. Protein-energy wasting may lower TIBC, leading to a TSAT within the normal range, even when iron deficiency is present. Iron and anemia indices have different mortality predictabilities, in that high serum ferritin but low iron, TIBC, and TSAT levels are associated with increased mortality, whereas hemoglobin exhibits a U-shaped risk for death. The increased mortality associated with targeting hemoglobin above 13 g/dL may result from iron depletion-associated thrombocytosis. Intravenous (IV) iron administration may not only decrease hemoglobin variability and ESA hyporesponsiveness, it may also reduce the greater mortality associated with the much higher ESA doses that have been used in some patients when targeting higher hemoglobin levels.

Serum prohepcidin is associated with soluble transferrin receptor-1 but not ferritin in healthy post-menopausal women

Hepcidin is a 25-amino-acid iron peptide hormone originated from its two precursors of prohepcidin (60-amino-acid) and preprohepcidin (84-amino-acid). Serum prohepcidin levels have been widely used to evaluate iron overload in clinical and preclinical studies. However, its usefulness is often questioned and its stepwise conversion mechanism remains largely unknown. Using New York University Women's Health Study subjects, we measured serum levels of prohepcidin with ELISA and hepcidin with mass spectrometry as well as ferritin and soluble transferrin receptor 1 (sTfR1) in 45 normal healthy post-menopausal women over a 1-year period with 2 samples per subject. We found that serum prohepcidin levels are correlated with the serum sTfR1 levels (r=0.45, p<0.01) but not to ferritin levels (r=0.08, p=0.60), suggesting that serum prohepcidin is not a biomarker of iron overload that was originally thought and designed for. Interestingly, serum hepcidin levels are associated with serum ferritin levels (r=0.64, p<0.0001) but not with sTfR1 levels (r=0.06, p=0.70), indicating that hepcidin is a measure of iron overload. Although hepcidin is a downstream product of prohepcidin, the amounts of hepcidin and prohepcidin are not related to each other (r=-0.007, p=0.90) under normal physiological conditions. The interrelationships between sTfR1 and prohepcidin or between ferritin and hepcidin suggest that ferritin- and sTfR1-sensed hepcidin conversion system exist in human body and maybe regulated at the post-translational level.

Association of prohepcidin and hepcidin-25 with erythropoietin response and ferritin in hemodialysis patients

Hepcidin is a key regulator of iron metabolism. In this study, we examined whether measurement of hepcidin is useful in assessing recombinant human erythropoietin (rHuEPO) responsiveness in regular hemodialysis (HD) patients in a cross-sectional fashion. We examined the association between serum prohepcidin, a prohormone of hepcidin, and rHuEPO dosage and the rHuEPO/hemoglobin (Hb) ratio in 75 HD patients. We also semiquantatively measured the peak intensity of serum hepcidin-25, the major form of mature hepcidin, in 24 HD patients by using surface-enhanced laser desorption ionization time of flight time mass spectrometry, and compared those between rHuEPO-hyporesponsive (rHuEPO 192 +/- 10 [126-252] IU/kg/week, n = 15) and responsive patients (rHuEPO 40 +/- 9 [0-81] U/kg/week, n = 9). A significant but weak relationship was found between serum prohepcidin and rHuEPO dosage (r = 0.24, p < 0.05) and rHuEPO/Hb ratio (r = 0.22, p = 0.06). However, prohepcidin did not become an indicator of hematopoietic parameters by multiple regression analysis. Serum hepcidin-25 intensity was significantly and positively correlated with ferritin (r = 0.51, p < 0.01) but not with log-transformed C-reactive protein. There was no difference in the intensities of serum hepcidin-25 between rHuEPO-hyporesponsive and responsive patients (64 +/- 10 vs. 52 +/- 16 AU, p = NS). It follows from these findings that the assessment of serum hepcidin using currently available assays was not valid in predicting rHuEPO responsiveness in chronic HD patients.