Serum Hepcidin-25 and All-Cause Mortality in Patients Undergoing Maintenance Hemodialysis

Iron Parameters in Patients Treated with Roxadustat for Anemia of Chronic Kidney Disease

Roxadustat is a novel agent with a distinct mechanism of action compared to erythropoiesis-stimulating agents (ESAs) and a potentially different combination of effects on iron parameters. This narrative review describes the effects of roxadustat on iron parameters and on hemoglobin levels in the context of iron supplementation in patients with anemia of non-dialysis-dependent (NDD) or dialysis-dependent (DD) chronic kidney disease (CKD). Roxadustat use was associated with a greater reduction in serum ferritin levels than seen with ESAs and an increase in serum iron levels compared to a decrease with ESAs. Decreases in transferrin saturation in patients treated with roxadustat were relatively small and, in the case of patients with NDD CKD, not observed by Week 52. These changes reflect the concomitant increases in both serum iron and total iron-binding capacity. Compared to placebo and an ESA, roxadustat improved iron availability and increased erythropoiesis while requiring less intravenous iron use. Hepcidin levels generally decreased in patients who received roxadustat compared to baseline values in all CKD populations; these decreases appear to be more robust with roxadustat than with an ESA or placebo. The mechanisms behind the effects of roxadustat and ESAs on iron availability and stores and erythropoiesis appear to differ and should be considered holistically when treating anemia of CKD.

Association between Iron Status and Survival in Patients on Chronic Hemodialysis

The aim of this study was to evaluate survival rates according to iron status in patients undergoing maintenance hemodialysis (HD). Thus, the National HD Quality Assessment Program dataset and claims data were used for analysis (n = 42,390). The patients were divided into four groups according to their transferrin saturation rate and serum ferritin levels: Group 1 (n = 34,539, normal iron status); Group 2 (n = 4476, absolute iron deficiency); Group 3 (n = 1719, functional iron deficiency); Group 4 (n = 1656, high iron status). Using univariate and multivariable analyses, Group 1 outperformed the three other groups in terms of patient survival. Using univariate analysis, although Group 2 showed a favorable trend in patient survival rates compared with Groups 3 and 4, the statistical significance was weak. Group 3 exhibited similar patient survival rates to Group 4. Using multivariable Cox regression analysis, Group 2 had similar patient survival rates to Group 3. Subgroup analyses according to sex, diabetic status, hemoglobin level ≥ 10 g/dL, and serum albumin levels ≥ 3.5 g/dL indicated similar trends to those of the total cohort. However, subgroup analysis based on patients with a hemoglobin level < 10 g/dL or serum albumin levels < 3.5 g/dL showed a weak statistical significant difference compared with those with hemoglobin level ≥ 10 g/dL, or serum albumin levels ≥ 3.5 g/dL. In addition, the survival difference between Group 4 and other groups was greater in old patients than in young ones. Patients with a normal iron status had the highest survival rates. Patient survival rates were similar or differed only modestly among the groups with abnormal iron status. In addition, most subgroup analyses revealed similar trends to those according to the total cohort. However, subgroup analyses based on age, hemoglobin, or serum albumin levels showed different trends.

Effect of different hemodialysis modalities on hepcidin clearance in patients undergoing maintenance hemodialysis

INTRODUCTION

Hepcidin is a master regulator of iron utilization and takes part in the pathophysiology of anemia in maintenance hemodialysis (MHD) patients. Hepcidin is a moderate-molecular-weight substance and partially binds to plasma proteins in the circulation, which theoretically might be removed efficiently by hemoperfusion (HP). This study aimed to compare the effect of different dialysis modalities on hepcidin removal and discuss its effect on the iron and anemia status in MHD patients.

MATERIALS AND METHODS

In a longitudinal interventional study of 26 stable MHD patients, the serum hepcidin, β2-microglobulin (β2-MG), and intact parathyroid hormone (iPTH) were measured before and after one treatment session of hemodialysis (HD), hemodiafiltration (HDF), HD + HP, and HDF + HP, separately. One-way analysis of variance (ANOVA) was used to identify the effect of dialysis modalities on the intra-dialysis clearance ratios.

RESULTS

The combined dialysis modalities (HD + HP and HDF + HP) achieved greater clearance ratios of serum hepcidin than HD and HDF alone, HD + HP vs. HD (16 ± 15% vs. 4 ± 13%, p < 0.001), HDF + HP vs. HDF (18 ± 5% vs. 10 ± 13%, p = 0.0036). Similarly, the combined dialysis modalities also performed better than HD and HDF alone in removing β2-MG. There was no significant difference in iPTH clearance among these four modalities, except that HDF + HP achieved a greater clearance ratio than HD. Furthermore, the anemia was improved after the 6-month treatment with regular HD/HDF plus HP, which was indicated by increasing hemoglobin (p = 0.0004) and reduction of erythropoiesis-stimulating agents (ESAs) resistance index (ERI) (p = 0.0431).

CONCLUSIONS

Our findings suggest that the combined dialysis modalities of HD/HDF plus HP could achieve better clearance ratios of hepcidin than HD/HDF alone, thereby, might improve iron utilization, and benefit anemia management in MHD patients. Further studies with larger sample-size patients and longer follow-up duration are still needed.

An easy, fast, and efficient assay for the quantification of peptide Hepcidin-25 in serum and plasma with LC-MS/MS

BACKGROUND

The peptide hormone hepcidin-25 plays an important role in iron metabolism. Low or high levels of hepcidin-25 are associated with various iron disorders; therefore, hepcidin-25 is an important biomarker. This study describes an easy and fast analytical assay for the quantification of hepcidin-25 with liquid chromatography-tandem mass spectrometry (LC-MS/MS).

METHODS

Sample preparation was performed by protein precipitation with trichloroacetic acid, and injection onto a LC-MS/MS was directly conducted from a LoBind 96-well plate.

RESULTS

The concentration range covered by the quality control samples, ranged from 0.25 nmol/L (12.3% CV) to 11.9 nmol/L (CV < 9%). Matrix effect was limited (mean recovery of 99.9% with a CV of 6.4%). The assay was validated for serum, EDTA and heparin plasma. An international secondary reference material was used for calibration. The reference interval (90% CL) was estimated for hepcidin-25 by analysing serum and plasma samples from 156 healthy subjects with a lower limit: 0.12 (0.07-0.19) and upper limit: 11.2 nmol/L (9.5-13.0).

CONCLUSIONS

We present a fast and easy assay for the quantification of hepcidin-25 in serum and plasma samples. The assay was successfully used for the detection of various forms of hereditary haemolytic anaemias, to characterize the interplay between erythropoiesis and iron levels.