Intravenous calcitriol improves anaemia and reduces the need for erythropoietin in haemodialysis patients

Effect of Vitamin D Supplementation on the Hemoglobin Level in Chronic Kidney Disease Patients on Hemodialysis: A Systematic Review and Meta-Analysis

The objective of this study was to evaluate the impact of vitamin D supplementation on hemoglobin levels (Hb) in patients with chronic kidney disease (CKD) undergoing hemodialysis. A systematic search was conducted in electronic databases (PubMed/Medline, Cochrane Library, and Google Scholar) from inception to April 21, 2023. Inclusion criteria were applied to select relevant studies. Statistical analyses were performed using Review Manager 5.4.1. A random-effects model was used to address heterogeneity, and the mean difference (MD) with the corresponding 95% confidence interval (CI) was reported. Ten studies were included in the analysis, comprising seven clinical trials, two randomized clinical trials, and one retrospective observational study. Subgroup analysis was conducted based on the duration of follow-up: 12 weeks, three months, six months, 12 months, 15 months, and 18 months. A significant increase in hemoglobin levels was observed after 12 months (MD = -0.98 [95% CI -1.88, -0.08]; p = 0.03; I2 = 91%) and 18 months (MD = -1.80 [95% CI -2.56, -1.04]; p < 0.00001; I2 = Not applicable). However, there was no statistically significant relationship between vitamin D supplementation and hemoglobin levels at 12 weeks, three months, six months, and 15 months. The pooled analysis demonstrated a significant increase in hemoglobin levels with vitamin D supplementation (MD = -0.61 [95% CI -0.96, -0.26]; p = 0.03; I2 = 60.7%). This analysis highlights the significant role of vitamin D supplementation in improving anemia in patients with CKD undergoing hemodialysis. Vitamin D supplementation was found to significantly increase hemoglobin levels, particularly after 12 months and 18 months of supplementation.

The effect of high-dose vitamin D supplementation on hepcidin-25 and erythropoiesis in patients with chronic kidney disease

BACKGROUND

Hepcidin is considered to play a central role in the pathophysiology of renal anemia. Recent studies in healthy individuals have demonstrated a suppressive effect of vitamin D (VD) on the expression of hepcidin. In this post-hoc analysis based on a randomized controlled study, we evaluated the effect of supplementing chronic kidney disease (CKD) patients (stage G3-G4) with a high daily dose of native VD on serum levels of hepcidin-25, the hepcidin/ferritin ratio, as well as on markers of erythropoiesis.

METHODS

Patients with CKD stage G3-G4 included in a double blind, randomized, placebo (PBO) controlled study with available hepcidin measurements were analyzed. Study subjects received either 8000 international units (IU) of cholecalciferol daily or PBO for 12 weeks. We evaluated the change in markers of hepcidin expression, erythropoiesis, and iron status from baseline to week 12 and compared the change between the groups.

RESULTS

Eighty five patients completed the study. Calcitriol, but not 25-hydroxyvitamin D (25(OH) D), was inversely correlated with serum levels of hepcidin-25 (rho = -0,38; p =  < 0, 01 and rho = -0,02; p = 0, 89, respectively) at baseline. Supplementation with VD significantly raised the serum concentration of serum 25(OH)D in the treatment group (from 54 (39-71) to 156 (120-190) nmol/L; p =  < 0, 01)) but had no effect on any of the markers of hepcidin, erythropoiesis, or iron status in the entire cohort. However, we did observe an increase in hemoglobin (HB) levels and transferrin saturation (TSAT) as compared to the PBO group in a subgroup of patients with low baseline 25(OH)D levels (< 56 nmol/L). In contrast, in patients with high baseline 25(OH)D values (≥ 56 nmol/L), VD supplementation associated with a decrease in HB levels and TSAT (p = 0,056) within the VD group in addition to a decrease in hepcidin levels as compared to the PBO group.

CONCLUSION

High-dose VD supplementation had no discernible effect on markers of hepcidin or erythropoiesis in the entire study cohort. However, in patients with low baseline 25(OH)D levels, high-dose VD supplementation associated with beneficial effects on erythropoiesis and iron availability. In contrast, in patients with elevated baseline 25(OH)D levels, high-dose VD supplementation resulted in a decrease in hepcidin levels, most likely due to a deterioration in iron status.

Impact of parathyroidectomy among nondiabetic hemodialysis patients with severe hyperparathyroidism

Background

Parathyroidectomy (PTX) is a treatment for hyperparathyroidism (HPT) and has uncertain risks and benefits. The aim of this study was to evaluate the effect of PTX versus nonoperative treatment among nondiabetic hemodialysis patients.

Methods

A retrospective matched cohort study was performed. Each PTX patient was matched with one patient who had severe HPT but rejected PTX. The patients were matched by sex, birth date, date of first dialysis, nondiabetic status, and left ventricular ejection fraction. The serum markers, survival, main adverse cardiovascular and cerebrovascular event (MACCE) rates, and hospitalization were compared between the PTX patients and matched non-PTX patients.

Results

There were 1143 patients at our center in the Chinese National Renal Data System (CNRDS) between 2010 and 2020. Of these, 75 PTX patients were matched with 75 non-PTX patients. Rapid decreases in the mean intact parathyroid hormone, calcium and phosphorus concentrations, and a gradual increase in hemoglobin concentration were observed in the PTX group. The mortality was 2.9 per 100 patient-years in the PTX group and 10.9 per 100 patient-years in the non-PTX group (p < 0.001). Compared with non-PTX patients, PTX patients had an adjusted HR for death of 0.236 (95% CI 0.108–0.518). The cumulative MACCE rates were 6.7 per 100 patient-years in the PTX group and 15.2 per 100 patient-years in the non-PTX group (p < 0.001). The adjusted HR of the occurrence of first MACCE for PTX patients compared with non-PTX patients was 0.524 (95% CI 0.279-0.982). The cumulative hospitalization rates were 50.3 per 100 patient-years in the PTX group and 66.5 per 100 patient-years in the matched non-PTX group (p < 0.001).

Conclusions

Compared with non-PTX patients, PTX was associated with an improvement in the biochemical measures and patient-level outcomes in nondiabetic hemodialysis patients with severe HPT.

Combination of Talazoparib and Calcitriol Enhanced Anticancer Effect in Triple−Negative Breast Cancer Cell Lines

Monotherapy for triple−negative breast cancer (TNBC) is often ineffective. This study aimed to investigate the effect of calcitriol and talazoparib combination on cell proliferation, migration, apoptosis and cell cycle in TNBC cell lines. Monotherapies and their combination were studied for (i.) antiproliferative effect (using real−time cell analyzer assay), (ii.) cell migration (CIM−Plate assay), and (iii.) apoptosis and cell cycle analysis (flow cytometry) in MDA−MB−468 and BT−20 cell lines. The optimal antiproliferative concentration of talazoparib and calcitriol in BT−20 was 91.6 and 10 µM, respectively, and in MDA−MB−468, it was 1 mM and 10 µM. Combined treatment significantly increased inhibition of cell migration in both cell lines. The combined treatment in BT−20 significantly increased late apoptosis (89.05 vs. control 0.63%) and S and G2/M populations (31.95 and 24.29% vs. control (18.62 and 12.09%)). Combined treatment in MDA−MB−468 significantly increased the S population (45.72%) and decreased G0/G1 (45.86%) vs. the control (26.79 and 59.78%, respectively). In MDA−MB−468, combined treatment significantly increased necrosis, early and late apoptosis (7.13, 33.53 and 47.1% vs. control (1.5, 3.1 and 2.83%, respectively)). Talazoparib and calcitriol combination significantly affected cell proliferation and migration, induction of apoptosis and necrosis in TNBC cell lines. This combination could be useful as a formulation to treat TNBC.

The effect of hypervitaminosis D and intoxication on haematological parameters

BACKGROUND

This study aims to compare the haematological parameters of patients with very high and normal 25-hydroxyvitamin-D3 (25(OH)D3) levels.

METHODS

This study was designed as a retrospective cross-sectional study. The patients were divided into three groups according to their 25(OH)D3 levels: groups 1, 2 and 3 are patients with normal 25(OH)D3 levels (30-88 ng/mL), hypervitaminosis D (89-149 ng/mL) and vitamin D intoxication (>150 ng/mL), respectively. According to vitamin D levels, statistical analysis was performed by comparing the biochemical and haematological data between the groups.

RESULTS

This study evaluated 120 patients (40 patients) in three equal groups. A statistically significant difference was found between the three groups in haemoglobin (p = 0.03), haematocrit (p = 0.01), red blood cell levels (p = 0.03), leukocyte count (p < 0.001), neutrophil count (p < 0.001), lymphocyte count (p = 0.006), mean platelet volume (p = 0.04), and neutrophil/lymphocyte ratio (p = 0.03). In post hoc analysis, haemoglobin, haematocrit and RBC were significantly higher in group 1 than in group 3 (post hoc Tukey, p < 0.05). A statistically significant negative correlation was noted between 25(OH)D3 level and haemoglobin (r = -0.236), haemotocrit (r = -0.230), and red blood cell (r = -0.265) levels.

CONCLUSIONS

Vitamin D intoxication has been observed to affect haemoglobin, haematocrit, and RBC levels negatively. However, more studies are needed to clarify the effects and mechanisms of high vitamin D levels on the haematopoietic system.

Managing Anemia across the Stages of Kidney Disease in Those Hyporesponsive to Erythropoiesis-Stimulating Agents

BACKGROUND

Patients with CKD frequently have anemia that results from iron-restricted erythropoiesis and inflammation. Anemia of CKD is currently managed with iron supplements and erythropoiesis-stimulating agents (ESAs) to promote erythropoiesis and with RBC transfusion in severe cases. Hyporesponse to ESAs, or the need for larger than usual doses to attain a given hemoglobin (Hb) level, is associated with increased morbidity and mortality and presents a pressing clinical challenge, particularly for patients on dialysis. This paper reviews ESA hyporesponse and potential new therapeutic options in the management of anemia of CKD.

SUMMARY

The most common causes of ESA hyporesponse include iron deficiency and inflammation, and to a lesser degree, secondary hyperparathyroidism, inadequate dialysis, malnutrition, and concomitant medications. Management of ESA hyporesponse is multipronged and involves treating low level infections, ensuring adequate nutrition, and optimizing iron status and dialysis modality, although some patients can remain refractory. Inflammation directly increases production and secretion of hepcidin, contributes to an impaired response to hypoxia, and suppresses proliferation of erythroid progenitors. Coordination of renal and hepatic erythropoietin (EPO) production and iron metabolism is under the control of hypoxia-inducible factors (HIF), which are in turn regulated by HIF-prolyl hydroxylases (HIF-PHs). HIF-PHs and hepcidin are therefore attractive potential drug targets particularly in patients with ESA hyporesponse. Several oral HIF-PH inhibitors have been evaluated in patients with anemia of CKD and have been shown to increase Hb and reduce hepcidin regardless of inflammation, iron status, or dialysis modality. These sustained effects are achieved through more modest increases in endogenous EPO compared with ESAs. Key Messages: Treatments that address ESA hyporesponse remain a significant unmet clinical need in patients with anemia of CKD. New therapies such as HIF-PH inhibitors have the potential to address fundamental aspects of ESA hyporesponse and provide a new therapeutic option in these patients.

Development of evocalcet for unmet needs among calcimimetic agents

INTRODUCTION

The calcium-sensing receptor is an important treatment target for secondary hyperparathyroidism (SHPT) in patients undergoing dialysis. In addition to vitamin D receptor activator, cinacalcet has recently been widely used for SHPT management, and the significant suppression of parathyroid hormone (PTH) with better control of serum calcium and phosphorus has been reported. However, low adherence and insufficient dose escalation mainly due to frequent gastrointestinal adverse events, still remain as major issues. To overcome these unmet needs, we have developed a new oral calcimimetic agent evocalcet, which has recently been approved by the Pharmaceutical Affairs Act in Japan.

AREAS COVERED

PubMed was searched from inception until April 2020 with the word evocalcet to summarize the development of this new calcimimetic agent, its pharmacokinetics, and the results of clinical trials, along with an overview of the differences among calcimimetic agents. This review also includes the management of SHPT with a focus on calcimimetics.

EXPERT OPINION

Evocalcet evoked fewer gastrointestinal-related adverse events while suppressing PTH at a lower dose than cinacalcet. These data suggest evocalcet may contribute to better adherence and sufficient dose escalation in patients with SHPT. Whether or not evocalcet improves clinical outcomes remains to be elucidated.

Recurrence of Hyperparathyroidism after Total Parathyroidectomy and Autotransplantation in Peritoneal Dialysis Patients

Objective

To evaluate the effectiveness of total parathyroidectomy (PTX) with autotransplantation in the treatment of secondary hyperparathyroidism (HPT), and to assess recurrence rate of HPT in this peritoneal dialysis (PD) population.

Design

A retrospective study in a single home PD unit.

Patients

Between 1994 and 1998, 19 of 574 patients on PD underwent PTX for treatment of secondary HPT.

Main Outcome Measures

Clinical and biochemical improvement, recurrence of HPT, improvement in anemia post-PTX.

Results

Nineteen (3.3%) patients required PTX between 1994 and 1998. These 5 men and 14 women ranged in age from 22 to 66 years; they had been on maintenance PD pre-PTX for 47.5 ± 38.1 months, and were followed for 26.1 ± 15.5 months post-PTX. Sixteen patients had temporary hypocalcemia that was managed by oral (n = 10) or intravenous (n = 6) calcium supplements and calcitriol, while 3 patients had severe “hungry bone” syndrome postoperatively. One patient had recurrent laryngeal nerve palsy post-PTX. Bone pain disappeared in all 12 patients. Pruritus improved in 12/13 patients; fatigue improved in 15/16 patients. Comparison showed significant differences between hemoglobin and hematocrit values 1 month pre-PTX and 12 months post-PTX ( p < 0.05). Parathyroid hormone (PTH) level in 15 (79%) patients returned to normal (≤€7.6 pmol/L) during the first month post-PTX. In 5/12 (42%) patients, PTH level was ≤ 7.6 pmol/L 2 years post-PTX, while in 2/12 (17%), PTH was > 22.8 pmol/L (three times normal) 2 years post-PTX, and 3/5 (60%) patients had a PTH > 22.8 pmol/L 3 years post-PTX.

Conclusions

Total PTX with autotransplantation is associated with a tendency for recurrence of HPT. Our findings suggest that total PTX with autotransplantation may be an ineffective procedure in controlling HPT over the long term.

Emerging Association Between Parathyroid Hormone and Anemia in Hemodialysis Patients

Anemia is a common complication of chronic kidney disease (CKD). There are various causes of renal anemia such as decreased production of erythropoietin, resistance to erythropoietin, shortened survival of red blood cells, and bone marrow fibrosis. Secondary hyperparathyroidism (SHPT) is a less recognized, but potentially significant cause of renal anemia in CKD patients. Parathyroid hormone (PTH) has been regarded as a uremic toxin that has multiple adverse effects, and its elevated levels have been associated with renal anemia in hemodialysis patients. Moreover, recent clinical studies have shown that the treatment of SHPT using either vitamin D receptor activators, calcimimetics, or parathyroidectomy leads to improvement of anemia, supporting the role of PTH in renal anemia. Emerging data have also indicated the involvement of bone-derived fibroblast growth factor 23 in renal anemia. This review summarizes recent insights into the role of PTH in renal anemia and discusses the importance of treating SHPT in improving the control of renal anemia in hemodialysis patients.

Randomized supplementation of 4000 IU vitamin D3 daily vs placebo on the prevalence of anemia in advanced heart failure: the EVITA trial

Background

Low 25-hydroxyvitamin D (25OHD) levels (< 75 nmol/l) are inversely associated with anemia prevalence. Since anemia and low 25OHD levels are common in patients with heart failure (HF), we aimed to investigate whether vitamin D supplementation can reduce anemia prevalence in advanced HF.

Methods

EVITA (Effect of Vitamin D on Mortality in Heart Failure) is a randomized, placebo-controlled clinical trial in patients with initial 25OHD levels < 75 nmol/l. Participants received either 4000 IU vitamin D₃ daily or a matching placebo for 36 months. A total of 172 patients (vitamin D group: n = 85; placebo group: n = 87) were investigated in this pre-specified secondary data analysis. Hemoglobin (Hb) and other hematological parameters were measured at baseline and study termination. Assessment of between-group differences in anemia prevalence and Hb concentrations was performed at study termination, while adjusting for baseline differences.

Results

In the vitamin D and placebo group, baseline proportions of patients with anemia (Hb < 12.0 g/dL in females and < 13.0 g/dL in males) were 17.2% and 10.6%, respectively (P = 0.19). At study termination, the proportion of patients with anemia in the vitamin D and placebo groups was 32.2% and 31.8%, respectively (P > 0.99). There was no between-group difference in change in the Hb concentrations (− 0.04 g/dL [95%CI:-0.53 to 0.45 g/dL]; P = 0.87). Results regarding anemia risk and Hb concentrations were similar in the subgroup of patients with chronic kidney disease (vitamin D group: n = 26; placebo group: n = 23). Moreover, results did not differ substantially when data analysis was restricted to patients with deficient baseline 25OHD levels.

Conclusions

A daily vitamin D supplement of 4000 IU did not reduce anemia prevalence in patients with advanced HF. Data challenge the clinical relevance of vitamin D supplementation to increase Hb levels.

Trial registration

The study was registered at EudraCT (No. 2010–020793-42) and clinicaltrials.gov (NCT01326650).

Electronic supplementary material

The online version of this article (doi:10.1186/s12937-017-0270-5) contains supplementary material, which is available to authorized users.

Vitamin D deficiency and anemia risk in children: a review of emerging evidence

There has been renewed scientific interest in the sequelae of vitamin D deficiency, given the emerging evidence on the diverse biologic functions of vitamin D, besides its fundamental role in bone and mineral metabolism. For the past decade, the evidence in the medical literature pointing to a relationship between anemia risk and vitamin D deficiency has been accumulating. This paper critically reviews the current evidence linking vitamin D deficiency to anemia risk in children. The synthesized evidence indicates that the studies, which were preponderantly conducted among the adult population, not only reported a bidirectional relationship between vitamin D deficiency and anemia but also showed a racial effect. In studies conducted among children, similar results were reported. Although the causal association of vitamin D deficiency with anemia risk (especially iron-deficiency anemia) remains debatable, the noncalcemic actions of the vitamin and its analogs hold prospects for several novel clinical applications. There is, however, unanimity in many reports suggesting that vitamin D deficiency is directly associated with anemia of chronic disease or inflammation. Despite the advances in unraveling the role of vitamin D in iron homeostasis, further research is still required to validate causality in the relationship between vitamin D deficiency and anemia, as well as to determine its optimal dosing, the ideal recipients for therapeutic intervention, and the preferred analogs to administer.

High-dose vitamin D3 reduces circulating hepcidin concentrations: A pilot, randomized, double-blind, placebo-controlled trial in healthy adults

BACKGROUND & AIMS

In vitro studies suggest that vitamin D may reduce hepcidin expression and pro-inflammatory cytokine release from monocytes. However, data assessing the vitamin D-mediated effects on iron recycling in healthy individuals are lacking. We aimed to examine the effect of high-dose vitamin D₃ on plasma hepcidin, inflammatory cytokine, and ferritin concentrations in healthy adults.

METHODS

This was a pilot, double-blind, placebo-controlled trial in healthy adults (N = 28) randomized to receive a one-time oral dose of 250,000 IU of vitamin D₃ or placebo. Between- and within-group differences in plasma hepcidin, pro-inflammatory cytokine [interleukin (IL)-1β, IL-6, IL-8, monocyte chemoattractant protein-1 (MCP-1)], and ferritin concentrations at baseline and 1 week were determined using two-sample and paired t-tests, respectively.

RESULTS

At baseline, plasma 25-hydroxyvitamin D [25(OH)D], hepcidin, pro-inflammatory cytokine, and ferritin concentrations did not differ between the two groups, and greater than 70% of subjects in both groups were vitamin D deficient (25(OH)D < 20 ng/mL). After 1 week, plasma hepcidin concentrations decreased by 73% from baseline in those who received vitamin D₃ (geometric mean ratio [GMR] = 0.27 (95% CI: 0.11-0.62); P = 0.005); there was no significant change in the placebo group (GMR = 0.73 (95% CI: 0.49-1.09); P = 0.11). Plasma cytokine and ferritin concentrations did not change significantly in either group.

CONCLUSIONS

High-dose vitamin D₃ significantly reduced plasma hepcidin concentrations in healthy adults 1 week post-dosing, without a change in plasma pro-inflammatory cytokine or ferritin concentrations. These data suggest that vitamin D may have a role in regulating iron recycling by acting independently of changes in pro-inflammatory markers.

ESA Hyporesponsiveness Is Associated with Adverse Events in Maintenance Hemodialysis (MHD) Patients, But Not with Iron Storage

Objective

It has been reported that hyporesponsiveness to erythropoiesis-stimulating agent (ESA) is associated with adverse events in patients on maintenance hemodialysis (MHD). However, it has not been determined whether higher iron storage is associated with an improved response, including better survival, to ESA.

Design and Method

We measured serum ferritin, hemoglobin (Hb), and transferrin saturation (TSAT) levels every three months for two years in 1,095 MHD patients. The weekly dose of ESA to Hb ratio was also calculated as an index of ESA responsiveness (ERI).

Results

A significant correlation (p<0.001, R = 0.89) between ferritin and Hb was only observed in the patients with ferritin levels <50 ng/mL. High-dose (≥50 mg/week) intravenous iron administration, female sex, low serum albumin, and angiotensin-converting enzyme inhibitor/angiotensin receptor blocker use were significant predictors of a high ERI value (>280); however, serum ferritin and TSAT levels did not predict a higher ERI. In the time-dependent Cox hazard model, the risk for a composite event in the patients with a high ERI (≥280) and a high ferritin level (≥100 ng/mL) was significantly greater (hazard ratio [HR], 2.09, P = 0.033) than that for patients with a high ERI and a low ferritin (<100 ng/mL) level.

Conclusion

Hb was dependent upon ferritin levels in patients with ferritin levels <50 ng/mL but not in patients with ferritin levels ≥50 ng/mL. Patients with hyporesponsiveness to ESA had a greater risk of composite events, but ERI was unrelated to iron storage.

High Fibroblast Growth Factor 23 Levels Associated With Low Hemoglobin Levels in Patients With Chronic Kidney Disease Stages 3 and 4

In chronic kidney disease (CKD), decreased erythropoietin production, low serum active vitamin D levels, and high renin-angiotensin-aldosterone activities had been regarded as major causes of renal anemia. At present, no clinical data are available to elucidate the association between renal anemia and fibroblast growth factor 23 (FGF23) levels in CKD. This study aimed to access whether FGF23 is involved in the pathogenesis of renal anemia. This cross-sectional observational study included 53 stable outpatients with CKD stages 3 and 4. Our primary predictor was serum FGF23 levels and outcome was hemoglobin levels. Measurements contained hemoglobin, FGF23, 25-hydroxyvitamin D, intact parathyroid hormone, plasma renin, serum aldosterone, HbA1C levels, lipid and iron profiles, and serum and urine electrolytes. Mean age of our patients was 66.4 ± 12.8 (SD) years, mean estimated glomerular filtration rate 33.5 ± 13.9 mL/min/1.73 m, median FGF23 level 200 (25th-75th percentile, 124-303) pg/mL, vitamin D level 19.5 (25th-75th percentile, 14.0-25.9) ng/mL, and hemoglobin level 12.7 (25th-75th percentile, 10.7-13.75) g/dL. Even after adjusting multiple variables, lower hemoglobin levels correlated significantly with FGF23 levels that were higher than the median value (>200 pg/mL). Moreover, after adjusting for aldosterone, but not 25-hydroxyvitamin D, it decreased the association with FGF23 that higher than median level and hemoglobin levels. We also observed a significant decrease of hemoglobin level in the higher FGF23 group who had a diabetes history. High FGF23 levels were observed to be associated with low hemoglobin levels, which may be partially mediated through the effects of serum aldosterone levels in our patients with CKD stages 3 and 4. Furthermore, we also presumed that diabetes itself may have an impact on the loop among FGF23, hemoglobin, and aldosterone levels in these CKD patients.

Vitamin D Supplementation and Hemoglobin Levels in Hypertensive Patients: A Randomized Controlled Trial

Epidemiological evidence suggests that circulating 25-hydroxyvitamin D (25OHD) levels are inversely associated with hemoglobin (Hb) levels and anemia risk. We evaluated whether vitamin D supplementation improves Hb levels and reduces anemia risk in hypertensive patients. Two hundred patients with 25OHD levels <75 nmol/L who attended the Styrian Vitamin D Hypertension Trial were included, of whom 188 completed the trial. Patients randomly received 2800 IU vitamin D3 daily or a matching placebo for eight weeks. Initially, the prevalence of anemic status (Hb levels <12.5 g/dL) and deficient 25OHD levels (<30 nmol/L) was 6.5% and 7.5%, respectively. All anemic patients had 25OHD levels >50 nmol/L. The mean (95% confidence interval) vitamin D effect on Hb levels was 0.04 (-0.14 to 0.22) g/dL (P = 0.661). Moreover, vitamin D treatment did not influence anemic status significantly (P > 0.999). Likewise, vitamin D had no significant effect on Hb levels in the subgroups of anemic patients or in patients with initial 25OHD levels <30 nmol/L. In conclusion, a daily vitamin D supplement of 2800 IU for eight weeks did not improve Hb levels or anemic status in hypertensive patients. Future trials should focus on anemic patients with deficient 25OHD levels (e.g., <30 nmol/L). This trial is registered with clinicaltrials.gov [NCT02136771].

Calcitriol-modulated human antibiotics: New pathophysiological aspects of vitamin D

Traditionally, calcitriol has been considered a calcium and phosphate regulating hormone, but has recently been shown to play a pivotal role in innate immunity. Many barrier and immune cells have membrane and intracellular receptors that recognize different microbial antigens. Activation of these receptors induces synthesis of 1α-hydroxylase, which acts on 25 hydroxyvitamin D to generate intracellular calcitriol. Calcitriol activates its receptor and enhances the synthesis of important human antibiotics like cathelicidin and β2-defensin while inhibiting hepcidin. These pluripotent peptides have an important role in innate immunity, and their regulation is abnormal in hypovitaminosis D. The literature on their secretion mechanisms, levels in different organic fluids, mechanism of action, and relationship with vitamin D is reviewed here.

Vitamin D and anemia: insights into an emerging association

PURPOSE OF REVIEW

The current review highlights recent findings in the emerging association between vitamin D and anemia through discussion of mechanistic studies, epidemiologic studies, and clinical trials.

RECENT FINDINGS

Vitamin D has previously been found to be associated with anemia in various healthy and diseased populations. Recent studies indicate that the association may differ between race and ethnic groups and is likely specific to anemia of inflammation. The mechanism underlying this association involves the reduction of proinflammatory cytokines by vitamin D and the direct suppression of hepcidin mRNA transcription. There is also evidence that vitamin D may be protective against anemia by supporting erythropoiesis. Other calciotropic hormones including fibroblast growth factor 23, and parathyroid hormone have also been found to be associated with iron homeostasis and erythropoiesis.

SUMMARY

Recent advances in our understanding of the association between vitamin D and anemia suggest that maintenance of sufficient vitamin D status may be important in preventing anemia, particularly in diseases characterized by inflammation. Early clinical trials have been promising, but further research is needed to define the efficacy of vitamin D as a future approach for the treatment of anemia.

Comparison of erythropoietin resistance in hemodialysis patients using calcitriol, cinacalcet, or paricalcitol

The erythropoiesis-stimulating agent (ESA) hyporesponsiveness index (EHRI) calculated as the weekly dose of EPO divided by weight (kg) divided by hemoglobin level (g/dL) has been considered useful to assess ESA resistance. Recent evidence suggests that active vitamin D, cinacalcet, and paricalcitol use may be related with lower ESA resistance. We conducted this observational cross-sectional study to investigate ESA resistance calculated by the EHRI among patients using calcitriol, cinacalcet, and paricalcitol. Participants underwent a medical history taken, physical examination, measurement of biochemical analysis, calculation of dialysis adequacy, and EHRI. Sixty-five patients did not receive any treatment regarding vitamin D, paricalcitol, and cinacalcet (group 1), 41 were taking only vitamin D (group 2), 50 were taking only paricalcitol (group 3), 19 were taking only cinacalcet (group 4), and 21 were taking paricalcitol + cinacalcet (group 5). The EHRI values for groups 1, 2, 3, 4, and 5 were 11.36 ± 8.72, 11.58 ± 5.72, 8.29 ± 5.54, 9.49 ± 4.61, and 8.91 ± 4.44 respectively (P =.034). Post hoc analysis showed that the EHRI differed between group 1 and group 3 (P =.017) and between group 2 and group 3 (P =.006). In linear regression analysis, use of paricalcitol was independently associated with EHRI. In conclusion, paricalcitol use was associated with lower EHRI levels as a measure of ESA resistance.

Independent association of circulating vitamin D metabolites with anemia risk in patients scheduled for cardiac surgery

BACKGROUND

Preoperative anemia is considered an independent risk factor of poor clinical outcome in cardiac surgical patients. Low vitamin D status may increase anemia risk.

METHODS

We investigated 3,615 consecutive patients scheduled for cardiac surgery to determine the association between preoperative anemia (hemoglobin [Hb] <12.5 g/dL) and circulating levels of the vitamin D metabolites 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25[OH]2D).

RESULTS

Of the study cohort, 27.8 % met the criteria for anemia. In patients with deficient 25OHD levels (<30 nmol/l) mean Hb concentrations were 0.5 g/dL lower than in patients with adequate 25OHD levels (50.0-125 nmol/l; P<0.001). Regarding 1,25(OH)2D, mean Hb concentrations were 1.2 g/dL lower in the lowest 1,25(OH)2D category (<40 pmol/l) than in the highest 1,25(OH)2D category (>70 pmol/l; P<0.001). In multivariable-adjusted logistic regression analyses, the odds ratios for anemia of the lowest categories of 25OHD and 1,25(OH)2D were 1.48 (95%CI:1.19-1.83) and 2.35 (95%CI:1.86-2.97), compared with patients who had adequate 25OHD levels and 1,25(OH)2D values in the highest category, respectively. Anemia risk was greatest in patients with dual deficiency of 25OHD and 1,25(OH)2D (multivariable-adjusted OR = 3.60 (95%CI:2.40-5.40). Prevalence of deficient 25OHD levels was highest in anemia of nutrient deficiency, whereas low 1,25(OH)2D levels were most frequent in anemia of chronic kidney disease.

CONCLUSION

This cross-sectional study demonstrates an independent inverse association between vitamin D status and anemia risk. If confirmed in clinical trials, preoperative administration of vitamin D or activated vitamin D (in case of chronic kidney disease) would be a promising strategy to prevent anemia in patients scheduled for cardiac surgery.

Effect of paricalcitol vs calcitriol on hemoglobin levels in chronic kidney disease patients: a randomized trial

BACKGROUND

Recent studies suggest that vitamin D deficiency represents an additional cofactor of renal anemia, with several mechanisms accounting for this relationship. In line with it, the administration of vitamin D or its analogues has been associated with an improvement of anemia. There are no data, however, about a direct effect of paricalcitol on hemoglobin (Hb) levels. Therefore, we conducted a study to determine whether paricalcitol, compared to calcitriol, improves anemia in patients with chronic kidney disease (CKD).

METHODS

In this randomized trial 60 CKD patients stage 3b-5 and anemia (Hb levels: 10-12.5 g/dL) were assigned (1:1) to receive low doses of calcitriol (Group Calcitriol) or paricalcitol (Group Paricalcitol) for 6 months. All the patients had normal values of plasma calcium, phosphorus and PTH, a stable iron balance, and normal values of C-Reactive Protein. The primary endpoint was to evaluate the effects of the two treatments on Hb levels; the modifications in 24hr-proteinuria (UProt) were also evaluated.

RESULTS

A significant Group x Time interaction effect was observed in the longitudinal analysis of Hb levels (F(1,172)=31.4, p<0.001). Subjects in Paricalcitol experienced a significant monthly increase of Hb levels equal to +0.16 g/dL [95% C.I. 0.10 to +0.22, p<0.001) while in Group Calcitriol, Hb decrease throughout the follow-up with an average monthly rate of -0.10 g/dL (95% C.I.: -0.17 to -0.04, p<0.001). In Group Paricalcitol, UProt was significantly reduced after 6 months [0.35 (0.1-1.2) vs 0.59 (0.2-1.6), p<0.01], whereas no significant difference emerged in Group Calcitriol. Plasma levels of calcium, phosphate, PTH and of inflammation markers remained in the normal range in both groups throughout the study.

CONCLUSIONS

Short-term exposure to paricalcitol results in an independent increase in Hb levels, which occurred with no modification of iron balance, inflammatory markers, and PTH plasma concentrations, and was associated with a decrease in UProt.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01768351.

Plasticity of renal endocrine function

The kidneys are important endocrine organs. They secrete humoral factors, such as calcitriol, erythropoietin, klotho, and renin into the circulation, and therefore, they are essentially involved in the regulation of a variety of processes ranging from bone formation to erythropoiesis. The endocrine functions are established by cells, such as proximal or distal tubular cells, renocortical interstitial cells, or mural cells of afferent arterioles. These endocrine cells are either fixed in number, such as tubular cells, which individually and gradually upregulate or downregulate hormone production, or they belong to a pool of cells, which display a recruitment behavior, such as erythropoietin- and renin-producing cells. In the latter case, regulation of humoral function occurs via (de)recruitment of active endocrine cells. As a consequence renin- and erythropoietin-producing cells in the kidney show a high degree of plasticity by reversibly switching between distinct cell states. In this review, we will focus on the characteristics of renin- and of erythropoietin-producing cells, especially on their origin and localization, their reversible transformations, and the mediators, which are responsible for transformation. Finally, we will discuss a possible interconversion of renin and erythropoietin expression.

Longitudinal assessments of erythropoietin-stimulating agent responsiveness and the association with specific clinical outcomes in dialysis patients

BACKGROUND

Dose requirements of erythropoietin-stimulating agents (ESAs) can vary considerably over time and may be associated with cardiovascular outcomes. We aimed to longitudinally assess ESA responsiveness over time and to investigate its association with specific clinical end points in a time-dependent approach.

METHODS

The German Diabetes and Dialysis study (4D study) included 1,255 diabetic dialysis patients, of whom 1,161 were receiving ESA treatment. In those patients, the erythropoietin resistance index (ERI) was assessed every 6 months during a median follow-up of 4 years. The association between the ERI and cardiovascular end points was analyzed by time-dependent Cox regression analyses with repeated ERI measures.

RESULTS

Patients had a mean age of 66 ± 8.2 years; 53% were male. During follow-up, a total of 495 patients died, of whom 136 died of sudden death and 102 of infectious death. The adjusted and time-dependent risk for sudden death was increased by 19% per 5-unit increase in the ERI (hazard ratio, HR = 1.19, 95% confidence interval, CI = 1.07-1.33). Similarly, mortality increased by 25% (HR = 1.25, 95% CI = 1.18-1.32) and infectious death increased by 27% (HR = 1.27, 95% CI = 1.13-1.42). Further analysis revealed that lower 25-hydroxyvitamin D levels were associated with lower ESA responsiveness (p = 0.046).

CONCLUSIONS

In diabetic dialysis patients, we observed that time-varying erythropoietin resistance is associated with sudden death, infectious complications and all-cause mortality. Low 25-hydroxyvitamin D levels may contribute to a lower ESA responsiveness.

The role of vitamin D in regulating the iron-hepcidin-ferroportin axis in monocytes

Chronic kidney disease affects 40% of adults aged 65 and older. Anemia of CKD is present in 30% of patients with CKD and is associated with increased cardiovascular risk, decreased quality of life, and increased mortality. Hepcidin-25 (hepcidin), the key iron regulating hormone, prevents iron egress from macrophages and thus prevents normal recycling of the iron needed to support erythropoiesis. Hepcidin levels are increased in adults and children with CKD. Vitamin D insufficiency is highly prevalent in CKD and is associated with erythropoietin hyporesponsiveness. Recently, hepcidin levels were found to be inversely correlated with vitamin D status in CKD. The aim of this study was to investigate the role of vitamin D in the regulation of hepcidin expression in vitro and in vivo. This study reports that 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃), the hormonally active form of vitamin D, is associated with decreased hepcidin and increased ferroportin expression in lipopolysaccharide (LPS) stimulated THP-1 cells. 1,25(OH)₂D₃ also resulted in a dose-dependent decrease in pro-hepcidin cytokines, IL-6 and IL-1β, release in vitro. Further, we show that high-dose vitamin D therapy impacts systemic hepcidin levels in subjects with early stage CKD. These data suggest that improvement in vitamin D status is associated with lower systemic concentrations of hepcidin in subjects with CKD. In conclusion, vitamin D regulates the hepcidin-ferroportin axis in macrophages which may facilitate iron egress. Improvement in vitamin D status in patients with CKD may reduce systemic hepcidin levels and may ameliorate anemia of CKD.

Non-linear relationship between serum 25-hydroxyvitamin D and hemoglobin in Korean females: the Korean National Health and Nutrition Examination Survey 2010-2011

BACKGROUND

Anemia and vitamin D deficiency are both important health issues; however, the nature of the association between vitamin D and either hemoglobin or anemia remains unresolved in the general population.

METHODS

Data on 11,206 adults were obtained from the fifth Korean National Health and Nutritional Examination Survey. A generalized additive model was used to examine the threshold level for relationship between serum 25-hydroxyvitamin D [25(OH)D] and hemoglobin levels. A multivariate logistic regression for anemia was conducted according to 25(OH)D quintiles. All analyses were stratified according to sex and menstrual status.

RESULTS

The generalized additive model confirmed a threshold 25(OH)D level of 26.4 ng/mL (male, 27.4 ng/mL; premenopausal females, 11.8 ng/mL; postmenopausal females, 13.4 ng/mL). The threshold level affected the pattern of association between 25(OH)D and anemia risk: the odds ratio of the 1(st) quintile but not the 2(nd), 3(rd), and 4(th) quintiles were significantly different from the 5(th) quintile in both premenopausal and postmenopausal females, however there was no obvious trend in males.

CONCLUSIONS

This population-based study demonstrated a non-linear relationship with a threshold effect between serum 25(OH)D and hemoglobin levels in females. Further interventional studies are warranted to determine whether the appropriate level of hemoglobin can be achieved by the correction of vitamin D deficiency.

Association of 25-hydroxyvitamin D with anemia risk in patients scheduled for cardiac surgery

INTRODUCTION

There is emerging data that vitamin D plays a role in erythropoiesis. Low 25-hydroxyvitamin D (25OHD) levels may therefore be a risk factor for anemia in patients scheduled for cardiac surgery.

METHODS

We investigated 4428 consecutive cardiac surgical patients to determine an association between anemia (hemoglobin concentration <12.5 g/dL, 27.1% of the study cohort) and circulating 25OHD.

RESULTS

In patients with severe vitamin D deficiency (25OHD < 12.5 nm), mean hemoglobin concentrations were 0.80 g/dL lower compared with patients with adequate 25OHD levels (50.0-100 nm). Hemoglobin levels were not significantly different at 25OHD levels above 100 nm compared with 50.0-100 nm. In multivariable-adjusted logistic regression analyses, the odds ratios for anemia of the groups with severe and moderate vitamin D deficiency (12.5-29.9 nm) were 1.70 (95% CI:1.09-2.63) and 1.41 (95% CI:1.02-1.96), respectively, compared with patients who had circulating 25OHD levels of 75-100 nm. Prevalence of deficient circulating 25OHD levels was highest in anemia of chronic kidney disease.

CONCLUSION

This cross-sectional study demonstrates an independent association between vitamin D status and anemia risk with optimal 25OHD levels of 75-100 nm. Randomized controlled trials are needed to clarify whether this association is causal.

Renal anaemia and EPO hyporesponsiveness associated with vitamin D deficiency: the potential role of inflammation

Resistance to erythropoiesis-stimulating agents (ESAs) has been observed in a considerable proportion of patients with chronic kidney disease (CKD) and it is reportedly associated with adverse outcomes, such as increased cardiovascular morbidity, faster progression to end-stage renal disease (ESRD) and all-cause mortality. The major causes of ESA resistance include chronic inflammation producing suppressive cytokines of early erythroid progenitor proliferation. In addition, pro-inflammatory cytokines stimulate hepcidin synthesis thus reducing iron availability for late erythropoiesis. Recent studies showing an association in deficiencies of the vitamin D axis with low haemoglobin (Hb) levels and ESA resistance suggest a new pathophysiological co-factor of renal anaemia. The administration of either native or active vitamin D has been associated with an improvement of anaemia and reduction in ESA requirements. Notably, these effects are not related to parathyroid hormone (PTH) values and seem to be independent on PTH suppression. Another possible explanation may be that calcitriol directly stimulates erythroid progenitors; however, this proliferative effect by extra-renal activation of 1α-hydroxylase enzyme is only a hypothesis. The majority of studies concerning vitamin D deficiency or supplementation, and degree of renal anaemia, point out the prevalent role of inflammation in the mechanism underlying these associations. Immune cells express the vitamin D receptor (VDR) which in turn is involved in the modulation of innate and adaptive immunity. VDR activation inhibits the expression of inflammatory cytokines in stromal and accessory cells and up-regulates the lymphocytic release of interleukin-10 (IL-10) exerting both anti-inflammatory activity and proliferative effects on erythroid progenitors. In CKD patients, vitamin D deficiency may stimulate immune cells within the bone marrow micro-environment to produce cytokines, inducing impaired erythropoiesis. Immune activation involves the reticuloendothelial system, increasing hepcidin synthesis and functional iron deficiency. Consequences of this inflammatory cascade are erythropoietin (EPO) resistance and anaemia. Given the key role of inflammation in the response to EPO, the therapeutic use of agents with anti-cytokines properties, such as vitamin D and paricalcitol, may provide benefit in the prevention/treatment of ESA hyporesponsiveness.

Vitamin D deficiency is an independent predictor of anemia in end-stage heart failure

Both, anemia and vitamin D deficiency are prevalent in patients with heart failure. According to recent evidence, vitamin D may stimulate erythropoiesis. We measured circulating 25-hydroxyvitamin D (25[OH]D), 1,25-dihydroxyvitamin D (1,25[OH](2)D) and hemoglobin (Hb) in a cross-sectional study in 364 end-stage heart failure patients awaiting cardiac transplantation, of whom 52.6% met the criteria for anemia (Hb < 13 g/dl in males and <12 g/dl in females). None of the patients were on erythrocyte-stimulating agents. Of the study cohort, 87.8% had 25(OH)D concentrations below 50 nmol/l. The mean Hb concentrations were significantly reduced in the lower tertiles of 25(OH)D and 1,25(OH)(2)D (P < 0.001). In multivariate-adjusted logistic regression analyses, the odds ratios for anemia of the lowest tertile of 25(OH)D (<18 nmol/l) and 1,25(OH)(2)D (<40 pmol/l) were 2.69 (1.46-5.00) and 4.08 (2.18-7.62) compared with their respective highest tertile (>32 nmol/l and >70 pmol/l). Patients with severe dual deficiency of 25(OH)D and 1,25(OH)(2)D had an odds ratio for anemia of 9.87 (95% CI 3.59-27.1) compared with patients in the highest tertile for both vitamin D metabolites. Circulating 1,25(OH)(2)D was directly related to circulating 25(OH)D levels and kidney function (P < 0.001), and inversely associated with C-reactive protein (P = 0.020). Our data demonstrate that vitamin D deficiency is independently associated with low Hb values and anemia in end-stage heart failure. Circulating 1,25(OH)(2)D is a better predictor of anemia than circulating 25(OH)D. Prospective randomized studies with administration of vitamin D (metabolites) will have to clarify if the association of vitamin D deficiency with anemia is causal.

Plasma 25-hydroxyvitamin d is independently associated with hemoglobin concentration in male subjects with type 2 diabetes mellitus

Introduction. It was reported that 25-hydroxyvitamin D level was independently associated with anemia in chronic kidney diseases, but the relation between vitamin D and anemia in diabetes mellitus is not still certain. We analyzed the relation between plasma 25-hydroxyvitamin D level and hemoglobin concentration. Materials and Methods. A cross-sectional study in male patients with type 2 diabetes was performed. Correlation coefficients and standardized partial regression coefficient for the hemoglobin concentration were evaluated. Results. Hemoglobin concentration was positively correlated with body mass index, HbA1c, estimated glomerular filtration rate, cholinesterase, and 25-hydroxyvitamin D level and negatively correlated with age, duration of diabetes mellitus, serum creatinine, and urinary albumin creatinine ratio. Multiple regression analysis revealed the independent relation of 25-hydroxyvitamin D to hemoglobin concentration. Conclusions. Plasma circulating form of vitamin D is significantly associated with hemoglobin concentration in diabetes mellitus independent of the clinical markers for kidney function or nutrition.

Improved Anemia and Reduced Erythropoietin Need by Medical or Surgical Intervention of Secondary Hyperparathyroidism in Hemodialysis Patients

BACKGROUND

The available literature is still controversial and shows that surgical (parathyroidectomy, PTX) or medical (calcitriol) treatment actually improved or even corrected the rhEPO-resistant anemia of ESRD patients with severe SHP. The aims of this study were to 1) assess the influence of SHP on hematological parameters in ESRD patients, 2) evaluate whether or not calcitriol could improve anemia and reduce the need of erythropoietin in dialysis patients, and 3) investigate the longitudinal effect of a parathyroidectomy for 6 months on regarding any improvements in calcitriol-refractory ESRD patients.

METHODS

37 chronic hemodialysis patients in Chang Gung Memorial Hospital Dialysis Unit were divided into two groups: patients with SHP (iPTH>300 pg/mL) and patients without SHP (ipTH<300 pg/mL) before calcitriol therapy was applied. Sixteen patients remain with a status of hyperparathyroidism and were considered candidates for calcitriol therapy. Furthermore, we divided the patients according to the response of HPT to calcitriol into responding patients and nonresponding patients. Among nonresponder groups, three patients agreed to accept surgical intervention to treat their hyperparathyroidism status.

RESULTS

The phosphate levels and serum alkaline phosphatase levels in patients with SHP were significantly higher when compared with those without SHP (P<0.05). As for the hematological data, hematocrit for patients with SHP was significantly higher than those without SHP (10.5 +/- 0.6 vs. 8.9 +/- 0.8, p<0.05). Other hematological parameters such as transferrin saturation and serum ferritin were not significantly different. We found a significant difference in alkaline phosphate levels in responding and nonresponding patients at 6 months on calcitriol therapy. Concomitantly, the hematocrit level is significantly higher in responding group when compared to those in nonresponding group (10.63 +/- 0.72 vs. 8.96 +/- 1.21, p<0.01). As for the dose of EPO requirement, significant difference between groups was also found after 6-month treatment (3617 +/- 2011 vs. 5416 +/- 1947, p<0.05). As for rhEPO dose requirement, positive effects of PTX were significantly found. The rhEPO doses needed to maintain patients in the hematocrit target range of 30-33% decreased gradually by 29% from 5323 +/- 1326 micro to 3774 +/- 2145 micro per week. The hematocrit level showed a significant increase at 3 months after PTX (p<0.05). This effect lasted until 6 months after PTX. The serum ferritin level was constantly around 350 to 400 pg/mL. While the transferrin saturation decreased 3 months after PTX (p<0.05) and recovered at 6 months.

CONCLUSION

ESRD patients with SHP, usually associated with more severe anemia show resistance to rhEPO. In this case, investigation of SHP is strongly recommended with measurement of serum PTH, phosphate and alkaline phosphatase level. Treatment of calcitriol has a beneficial effect on renal anemia in ESRD patients with SHP. In addition, PTX could also provide another choosing therapy in improving renal anemia when medical treatment fails.

Anaemia and mineral bone disorder in chronic kidney disease: a review of the current literature and implications for clinical nursing practice

Secondary hyperparathyroidism (SHPT) is one of the factors reported to have a negative impact on anaemia of chronic kidney disease (ACKD) and its treatment. SHPT is one of the abnormalities resulting from altered bone mineral metabolism. Five possible mechanisms have been proposed as to how SHPT impacts on anaemia in this paper. Each of these mechanisms will be considered and the treatment options reviewed including the implications for erythropoietic stimulating agents (ESA) prescribing. Anaemia and SHPT are both strongly predictive of complications and death from cardiovascular events in patients with chronic kidney disease (CKD). Nursing care of this group of patients should, therefore, be holistic in order to ensure optimum management. Ways in which we can practice to enhance quality of life and outcomes in this patient population will be discussed.

Predictors of hyporesponsiveness to erythropoiesis-stimulating agents in hemodialysis patients

BACKGROUND

Identification of predictors of hyporesponsiveness to erythropoietin-stimulating agents (ESAs) in hemodialysis (HD) patients may help improve anemia management and reduce hemoglobin level variability.

STUDY DESIGN

We conducted repeated-measure and logistic regression analyses in a retrospective cohort of long-term HD patients to examine the association of iron markers and measures of renal osteodystrophy with ESA responsiveness. The ESA response coefficient at the individual level, ie, the least confounded dose-response association, was separated from the population level, assumed to represent confounding by medical indication.

SETTING/PARTICIPANTS

The national database of a large dialysis organization (DaVita Inc, El Segundo, CA) with 38,328 surviving prevalent HD patients during 12 months who received ESA for at least 3 consecutive calendar quarters was examined.

PREDICTORS

Serum levels of ferritin, iron saturation ratio, intact parathyroid hormone, and alkaline phosphatase. OUTCOMES/OTHER MEASUREMENTS: The main outcome was case-mix-adjusted hemoglobin response to quarterly averaged ESA dose at the individual level. The odds ratio (OR) of the greatest versus poorest ESA-response quartile at the patient level was calculated. OR less than 1.0 indicated ESA hyporesponsiveness, and OR greater than 1.0, enhanced responsiveness.

RESULTS

Mean ESA-response coefficients of the least to most responsive quartiles were 0.301 +/- 0.033 (SD), 0.344 +/- 0.004, 0.357 +/- 0.004, and 0.389 +/- 0.026 g/dL greater hemoglobin level per 1,000 U/wk greater ESA dose in each quarter, respectively. The ORs of greatest versus poorest ESA responsiveness at the patient level were serum ferritin level less than 200 ng/mL (0.77; 95% confidence interval [CI], 0.70 to 0.86; reference, 200 to 500 ng/mL), iron saturation ratio less than 20% (0.54; 95% CI, 0.49 to 0.59; reference, 20% to 30%), intact parathyroid hormone level of 600 pg/mL or greater (0.54; 95% CI, 0.49 to 0.60; reference, 150 to 300 pg/mL), and alkaline phosphatase level of 160 IU/L or greater (0.64; 95% CI, 0.58 to 0.70; reference, 80 to 120 IU/L). Lower estimated dietary protein intake and serum levels of nutritional markers were also associated with greater risk of ESA hyporesponsiveness.

LIMITATIONS

Our results may incorporate uncontrolled confounding. Achieved hemoglobin level may have different associations than targeted hemoglobin level.

CONCLUSIONS

In long-term HD patients, low iron stores, hyperparathyroidism, and high-turnover bone disease are associated with significant ESA hyporesponsiveness. Prospective studies are needed to verify these associations.

Current Approaches in the Treatment of Chronic Kidney Disease Mineral and Bone Disorder

Patients with chronic kidney disease (CKD) develop mineral and bone disorder (MBD), a common and important complication, as a result of impaired phosphorus excretion and reduced vitamin D activation. Altered mineral metabolism is now recognized as an independent cardiovascular risk factor in end-stage renal disease patients and contributes to the risk for accelerating vascular calcification. CKD patients are at high risk for cardiovascular disease and vascular calcification which account for the high morbidity and mortality in this patient population. Pharmacotherapeutic interventions are necessary to manage and treat the condition. Multiple classes of agents including phosphorus binders, vitamin D analogs, and calcimimetics are now available to treat CKD-MBD. Recent data have shown that treatment with sevelamer and vitamin D analogs are associated with a reduction in calcification and cardiovascular mortality and improved survival. This article provides an overview of the strategies and considerations for the management of CKD-MBD, as well as their implications on clinical outcomes.

Possible Influence of Vitamin D Receptor Gene Polymorphisms on Recombinant Human Erythropoietin Requirements in Dialysis Patients

BACKGROUND

Vitamin D receptor (VDR) gene polymorphisms have been widely studied, especially to analyze their effects on calcium-phosphorus metabolism and secondary hyperparathyroidism in patients on dialysis. In this study, we sought to investigate the possible effects of these polymorphisms on the anemia of renal failure and recombinant human erythropoietin (rHuEPO) responses among patients receiving hemodialysis.

METHODS

One hundred twenty-eight patients (52 females/76 males) underwent genotyping for the insertion/deletion Bsml (B-->b, restriction site, exon VIII-->IX) and Tagl (T-->t, 352 exon IX) VDR gene polymorphisms. The mean value of the last 6 months' monthly evaluated laboratory values (C-reactive protein, hemoglobin, iron indices, PTH, and albumin) and clinical findings (rHuEPO requirement, cumulative iron supplementation doses, and body weight) were analyzed retrospectively excluding patients with chronic inflammation, hemolytic anemia, or active blood loss such as gastrointestinal bleeding.

RESULTS

Mean age and dialysis durations were 41.5 +/- 11.8 years and 91.8 +/- 45.3 months, respectively. Polymorphism percentages were as follows: Bsml; BB/Bb/bb: 32.2/63.6/4.2 and Tagl; TT/Tt/tt: 40.5/55.4/4.1%, respectively. BB variant of Bsml gene was related to lower rHuEPO needs (P < .05) and also higher hemoglobin levels (P < .005) when compared with the Bb/bb variant. Considering Tagl variants, transferrin saturation levels were lower (P < .03) among patients with the Tt/tt variant, but there was no other significant difference in the mean values of other data between TT and Tt/tt variants.

CONCLUSION

The BB variant of Bsml was related to decreased rHuEPO requirements to achieve higher hemoglobin levels among maintenance hemodialysis patients without chronic inflammation.

Elderly patients on chronic hemodialysis with hyperparathyroidism: increase of hemoglobin level after intravenous calcitriol

In patients on chronic hemodialysis (CHD), hyperparathyroidism (HPTH) is associated with anemia and resistance to erythropoietin (EPO). In the last few years, calcitriol intravenously (IV) has been used with success in the treatment of the HPTH, secondary to chronic renal failure. However, the effects of calcitriol on the hematological parameters of these patients have never been well evaluated. This study included 11 elderly CHD patients (f = 6, m = 5; mean age = 73.6 years, mean time on CHD = 42.8 months) with HPTH under EPO therapy (IV). They were treated for 12 months with calcitriol IV (mean dose = 2.33 mcg/pt/week). Patients with iron deficiency anemia (ferritin < 200 ng/ml) were excluded. The patients were compared before and after 12 months of calcitriol treatment, with respect to several laboratory parameters and with respect to EPO dose. A paired t-test was used. After treatment, we found a decrease of PTH (634 vs. 418 pg/ml, P = 0.029); the serum calcium increased (8.8 vs. 9.9 mg/dl, P = 0.002); no differences were noted in the plasma levels of alkaline phosphatase, phosphorous, BUN, creatinine, Na and K. Mean levels of Hb (10.2 vs. 11.4 g/dl, P = 0.004) and the Hct (30 vs. 34.3, P = 0.004) increased after 12 months of calcitriol; the levels of serum iron (70 vs. 78 microg/dl, P = ns) and ferritin (531 vs. 785 ng/ml, P = ns) and the EPO dose (105 vs. 100 U/kg/week, P = ns) were similar before and after treatment. Our data show that the treatment of HPTH in CHD elderly patients with calcitriol can increase Hb level without increasing EPO dose.

Genetics in Dialysis: Gene Polymorphism Association Studies in Dialysis: Anemia and Host Immunity

The typical complications of end-stage renal disease (ESRD) vary in frequency and severity. Whereas anemia of chronic kidney disease might require high doses of exogenous erythropoietin (EPO) in some individuals, others hardly ever need hormone replacement. The same observation can be made for immune defense functions in patients with ESRD. Our understanding of the functional consequences of genetic polymorphisms in a wide array of genes has recently gained momentum. In patients with ESRD, interindividual differences in anemia parameters have been linked in part to genetic polymorphisms. Indeed, although inflammation is an important predictor of the need for EPO, to date a link to cytokine gene polymorphisms has not been established. However, the need for EPO has been linked to polymorphisms in the angiotensin-converting enzyme (ACE) and vitamin D receptor genes. In contrast, in dialysis patients, interindividual variability in host immune responses, including nonspecific (bacterial) and antigen-specific (viral) immune mechanisms has been linked to variations in the interleukin-10 and myeloperoxidase genes as well as variability in human leukocyte antigens (HLAs). In conclusion, the role of genetic polymorphisms in predicting the development and severity of anemia in chronic kidney disease as well as host immune competence is in its infancy and warrants further inquiry.

Hormonal adjuvants for the treatment of renal anaemia

Hormonal adjuvants, besides being erythropoietic agents, broaden the spectrum of therapeutic options for the treatment of the anaemia of chronic kidney disease (CKD). Lowering elevated parathyroid hormone levels by oral calcium supplementation and phosphate restriction, by varying dialysate calcium concentrations, by administration of vitamin D3 derivatives and, in the near future, by treatment with calcimimetics may prove efficient in some patients to fight extensive requirements of erythropoietic agents. Clinical evidence for a principal role of secondary hyperparathyroidism in resistance to erythropoietin, however, is lacking. Active vitamin D3 derivatives, in addition to their beneficial effects on secondary hyperparathyroidism, appear to exert a direct, stimulatory action on erythroid precursor cells and possibly also an inhibitory action on collagen synthesis by bone marrow stromal cells. Growth hormone (GH) induces insulin-like growth factor (IGF)-1, which in turn counteracts apoptosis similarly to erythropoietin, and fosters proliferation of burst- and colony-forming units-erythroid (BFU-E, CFU-E). If erythropoietic agents improve survival of CKD patients, a similar benefit should apply for strategies that increase synthesis and bioavailabilty of IGF-1. The latter appears to be reduced in CKD patients, and zinc supplementation potentially enhances it via an increase in free IGF-1. Finally, androgens also exert anti-anaemic effects. Nandrolone decanoate constitutes the only androgen currently applicable for selected male dialysis patients over the age of 50 years. It should not be given to women, however, because of serious side effects. Collectively, hormonal interventions offer the potential to reduce requirements of erythropoietic agents, and some may also improve physical performance.

Calcitriol Increases Burst-Forming Unit-Erythroid Proliferation in Chronic Renal Failure

BACKGROUND

Calcitriol (C) improves anemia in chronic renal failure. This effect may be related to the suppression of iPTH release, or to a direct effect on erythropoiesis.

METHODS

Thirty-three patients with chronic renal failure were enrolled; among them, 24 were on chronic hemodialysis and 9 on conservative management. None had other chronic or hematological disease, aluminum levels were below 20 microg/l and DFO testing was negative. The iPTH range was 250-480 pg/l. None were treated with C or r-HuEpo. In vitro study: Samples were drawn for a basal erythroid precursor (burst forming unit-erythroid BFU-E) study: Mononuclear cells were incubated for 14 days with r-HuEpo 3U/ml (A), r-HuEpo 3U/l + C 30 pg (B), r-HuEpo 3U/ml + C 300 pg (C), or r-HuEpo 30 U/ml + C 300 pg (D). In vivo study: After the basal evaluation, 10 patients on chronic dialysis were treated with C (Calcijex-Abbott) 1 microg three times a week, and 4 patients served as controls. BFU-E studies were performed after 1, 2 and 4 months.

RESULTS

In vitro, culture B showed increased BFU-E proliferation vs. A (41 +/- 23 vs. 27 +/- 15, p < 0.02); in cultures C and D, proliferation was 61 +/- 31 and 78 +/- 42, respectively, p < 0.01 vs. A. There was no difference among patients with predialysis renal failure and those on dialysis. BFU-E proliferation was inversely related to basal Hb (p < 0.04) and CRP levels (p < 0.05). During the in vivo study, all cultures showed a progressive increase in proliferation without a plateau level (basal, after 1, 2 and 4 months, respectively) In A: 17 +/- 8, 22 +/- 13, 30.9 +/- 14.9, 41.4 +/- 20; in B: 27.3 +/- 15, 35.6 +/- 20, 45.5 +/- 21, 57 +/- 26; in C: 48.2 +/- 20.6, 63.7 +/- 32, 75.7 +/- 37, 83 +/- 40; in D: 72 +/- 24, 91 +/- 42, 106 +/- 42, 110 +/- 42.3 (all p < 0.001). Hb and Hct showed a significant increase (p < 0.03) in the treatment group. The decrease in iPTH was not related to BFU-E proliferation.

CONCLUSIONS

In chronic uremia, C has a direct effect on erythroid precursors proliferation, as demonstrated both in vitro and in vivo, with a synergistic effect with r-HuEpo. C may be a useful adjuvant therapy to r-HuEpo treatment.

Effects of parathyroidectomy on iron homeostasis and erythropoiesis in hemodialysis patients with severe hyperparathyroidism

AIMS

Secondary hyperparathyroidism (HPT) worsens anemia and may cause hyporesponsiveness to recombinant human erythropoietin therapy (r-HuEPO). To investigate the effect of parathyroidectomy (PTX) on iron homeostasis and erythropoiesis, we conducted a prospective study in chronic hemodialysis patients who underwent PTX.

METHODS

Thirty-two patients were enrolled in this study. Based on the increases in hemoglobin level after PTX, patients were divided into responders and nonresponders. Iron homeostasis and erythropoiesis were assessed before and 1 and 3 months after PTX, hemoglobin and parathyroid hormone levels were monitored until 6 months after PTX.

RESULTS

In the responders, increased hemoglobin levels were observed in 15 patients at 1 and 3 months after PTX (8.0 +/- 0.8 g/dl vs. 9.2 +/- 1.3 and 10.1 +/- 0.9 g/dl, p < 0.05). The nonresponders had higher pre-PTX hemoglobin levels than the responders (10.3 +/- 1.6 g/dl vs. 8.0 +/- 0.8 g/dl, p < 0.05). There was no further increase in hemoglobin at 6 months compared to 3 months after PTX in both groups. In neither group did PTX affect serum ferritin, transferrin saturation and serum erythropoietin level. Serum soluble transferrin receptor (sTfR) concentration was found to be higher in responders than in nonresponders (3.32 +/- 1.28 mg/l vs. 1.70 +/- 0.31 mg/l, p < 0.05).

CONCLUSIONS

We conclude that PTX can improve anemia in hemodialysis patients with severe hyperparathyroidism and greater resistance to r-HuEPO therapy. The reversing of anemia does not involve altering iron mobilization. Pre-PTX hemoglobin and serum sTfR levels can predict the effect of PTX on correcting anemia.

Supplemented very low protein diet ameliorates responsiveness to erythropoietin in chronic renal failure

BACKGROUND

The aim of this study was to evaluate the relationship between uremic state and erythropoiesis in patients with predialytic chronic renal failure (CRF).

METHODS

We monitored for 2 years the erythropoietin (EPO) requirement in patients with advanced CRF (creatinine clearance < or =25 mL/min), randomized to either low protein diet (LPD) group (0.6 g/kg body weight/day, N = 10) or very low protein diet (VLPD) group (0.3 g/kg body weight/day, N = 10) supplemented with a mixture of ketoanalogs and essential amino acids, both kept at target hemoglobin levels.

RESULTS

The achieved protein intake after 6 months was 0.79 +/- 0.02 g/kg body weight/day and 0.50 +/- 0.02 g/kg body weight/day in LPD and VLPD, respectively; such a difference was maintained up to the end of follow up. The final hemoglobin values did not differ from the basal values in either group (11.5 +/- 0.2 g/dL and 11.5 +/- 0.3 g/dL). EPO dose, that was similar at baseline (62.4 +/- 9.6 UI/kg body weight/week and 61.8 +/- 8.8 UI/kg body weight/week subcutaneously), remained unchanged in LPD but progressively decreased in VLPD down to the final value of 41.2 +/- 7.0 UI/kg body weight/week (P < 0.0001 vs. basal and LPD). VLPD was associated with a decrease of urinary excretion and serum levels of urea nitrogen and phosphate; however, EPO requirement was not correlated with the changes of these parameters. On the contrary, the variation of EPO dose directly correlated with the modification of parathyroid hormone (PTH) levels, that diminished from 229 +/- 55 pg/mL to 118 +/- 16 pg/mL (P < 0.0001) in VLPD and did not change in LPD.

CONCLUSION

In patients with advanced CRF, an effective decrease of protein intake of 0.3 g/kg body weight/day induces a reduction of about 35% of the EPO dose required to maintain the target hemoglobin levels. This effect appears dependent on the correction of a moderate secondary hyperparathyroidism.

The impact of vitamin D receptor genotype on the management of anemia in hemodialysis patients

BACKGROUND

Both in vitro and in vivo studies have shown that calcitriol, the active form of vitamin D, is involved in hematopoiesis. We hypothesized that the vitamin D receptor (VDR) genotype, which may differentiate response to endogenous or exogenous active vitamin D, has a role in the management of anemia in hemodialysis (HD) patients.

METHODS

The VDR BsmI gene polymorphism was determined in 91 HD patients and 85 healthy controls. In addition to well-known factors responsible for both anemia and inadequate response to erythropoietin (EPO), we examined the contribution of the VDR genotype to hematocrit (Hct), hemoglobin (Hb) level, total weekly dose of EPO, and EPO-Hb ratio as an index of patient EPO need.

RESULTS

Genotype distributions for the VDR gene were under the Hardy-Weinberg equilibrium and similar in patients and controls (genotypes BB, Bb, and bb: 22.0%, 38.5%, and 39.5% in patients versus 24.7%, 48.2%, and 27.1% in controls). There were statistically significant differences in Hct, Hb level, EPO dose, and EPO-Hb ratio in patients with the three BsmI genotypes, whereas the other parameters were the same. Comparison of patients with an Hb level less than versus greater than 11 g/dL showed that the former patients had lower albumin levels (P = 0.001), higher C-reactive protein levels (P = 0.014), and a greater frequency of BB genotype (P < 0.001). Similarly, comparison of patients with an EPO-Hb ratio in the highest quartile versus those in the lowest quartile showed that the former patients had lower albumin and transferrin levels (P = 0.013 for both) and greater frequencies of BB genotype (P = 0.016). In logistic regression analysis, both BB genotype and low serum albumin level were found to be the only independent predictors for an Hb level less than 11 g/dL (P < 0.001 and P = 0.046, respectively). Both parameters also predicted being in the highest quartile of EPO-Hb ratio (P = 0.004 for both).

CONCLUSION

The VDR BsmI gene polymorphism may predict both Hb level and EPO need in HD patients. However, because the underlying mechanisms have not been clarified in the present study, further research on this issue is needed.

Early effects of parathyroidectomy on erythropoietin production in secondary hyperparathyroidism

BACKGROUND

Secondary hyperparathyroidism (2-HPT) has an adverse effect on renal anemia and may cause a hyporesponsiveness to recombinant human erythropoietin (rHuEpo) in patients with chronic renal failure. The early effects of parathyroidectomy (PTx) on renal anemia, erythropoietin production, and nutritional state were examined.

METHODS

Twenty-nine patients under hemodialysis therapy received a PTx for 2-HPT. They were prospectively studied regarding hematological parameters, rHuEpo use, plasma erythropoietin levels, and nutritional condition until 12 months after PTx.

RESULTS

The hemoglobin level showed a significant increase from 3 months after PTx (10.2% +/- 1.5% to 11.2% +/- 1.3%; P <0.01), associated with a consistent increase of the reticulocyte count. These changes lasted until 12 months after PTx. The plasma erythropoietin level showed a gradual increase of up to about 5 times the level of the preoperative value, until 12 months after PTx (22.6 +/- 10.1 to 106.3 +/- 112.1 mU/mL; P <0.001). The weekly dose of rHuEpo administration decreased after 3 months. The serum levels of albumin and total protein also significantly and gradually improved until 12 months after PTx.

CONCLUSIONS

PTx caused a significant early improvement in renal anemia in patients with secondary hyperparathyroidism. This effect may be caused by an enhanced erythropoietin production and may also be partially due to the improved nutritional state after PTx.