Iron therapy, advanced oxidation protein products, and carotid artery intima-media thickness in end-stage renal disease

Advanced oxidation protein products induce vascular calcification by promoting osteoblastic trans-differentiation of smooth muscle cells via oxidative stress and ERK pathway

Vascular calcification is an actively regulated process similar to bone formation. Advanced oxidation protein products (AOPPs) have been demonstrated to be novel markers of oxidant-mediated protein damage. The present study investigated the role of AOPPs in inducing osteoblastic trans-differentiation and calcification of smooth muscle cells in vitro. We found that AOPPs directly increased the calcium deposition and expression of core binding factor-alpha1 (CBF-alpha1) and osteopontin (OPN) and significantly decreased SM-alpha-actin expression in human aortic smooth muscle cells (HASMCs). AOPPs increased intracellular oxidative stress, which was inhibited by vitamin E. Vitamin E also inhibited AOPP-induced calcium content and osteoblast differentiation of HASMCs. Furthermore, the inhibitor of ERK significantly suppressed the effects of AOPPs on calcification and osteoblast marker expression. These findings suggest that AOPPs induce vascular calcification by promoting osteoblast differentiation of smooth muscle cells via oxidative stress and ERK pathway.

The association of biomarkers of iron status with peripheral arterial disease in US adults

Background

Several studies have examined the association of biomarkers of iron metabolism with measures of carotid artery atherosclerosis, with inconsistent results. Few studies, however, have evaluated the association between biomarkers of iron metabolism and peripheral arterial disease (PAD). The purpose of this study is to examine the association of ferritin and transferrin saturation with PAD.

Methods

Serum ferritin, transferrin saturation, and PAD, defined as having an ankle-brachial blood pressure index <0.9, were measured in 1,631 men and 1,031 postmenopausal women participating in the 1999-2002 National Health and Nutrition Examination Survey (NHANES).

Results

The multivariable adjusted odds ratios (95% confidence interval) for PAD associated with a two-fold increase in serum ferritin and transferrin saturation were 1.18 (1.00-1.41) and 1.45 (0.83-2.51), respectively, for men and 1.04 (0.87-1.25) and 1.55 (0.98-2.45), respectively, for women. After stratifying by cholesterol levels, the multivariable adjusted odds ratios (95% confidence intervals) for PAD associated with a two-fold increase in ferritin and transferrin saturation was 1.04 (0.78-1.39) and 0.73 (0.35-1.50), respectively, for men with total cholesterol <200 mg/dL and 1.30 (0.99-1.72) and 2.59 (0.99-6.78), respectively, for men with total cholesterol ≥ 200 mg/dL (p-value for interaction was 0.58 for ferritin and 0.08 for transferrin saturation). After stratifying by cholesterol levels, the multivariable adjusted odds ratios (95% confidence intervals) for PAD associated with a two-fold increase in ferritin and transferrin saturation was 0.66 (0.41-1.05) and 0.75 (0.44-1.28), respectively, for women with total cholesterol <200 mg/dL, and 1.20 (0.95-1.51) and 2.07 (1.01-4.22), respectively, for women with total cholesterol ≥ 200 mg/dL (p-value for interaction was 0.05 for ferritin and 0.02 for transferrin saturation).

Conclusion

In this large nationally representative sample of men and postmenopausal women, we found a modest association of ferritin and transferrin saturation with PAD, particularly among those with high cholesterol levels.

Anemia in heart failure: pathophysiologic insights and treatment options

Anemia has been recognized as a very common and serious comorbidity in heart failure, with a prevalence ranging from 10 to 79%, depending on diagnostic definition, disease severity and patient characteristics. A clear association of anemia with worse prognosis has been confirmed in multiple heart failure trials. This finding has recently triggered intense scrutiny in order to identify the underlying pathophysiology and the best treatment options. Etiology is multifactorial, with iron deficiency and cytokine activation (anemia of chronic disease) playing the most important roles. Treatment is aimed at not only restoring hemoglobin values back to normal, but also at improving the patient's symptoms, functional capacity and hopefully the outcome. Iron supplementation and erythropoietin-stimulating agents have been used for this purpose, either alone or in combination. In this review, the recent advances in elucidating the mechanisms leading to anemia in the setting of heart failure are presented and the evidence supporting the use of different treatment approaches are discussed.

Evaluation of Oxidative Stress after Repeated Intravenous Iron Supplementation

Parenteral iron has been recommended for the treatment of iron deficiency in the majority of maintenance hemodialyzed (HD) patients. However, iron supplementation and consequent over saturation of transferrin and high iron levels, may aggravate oxidative stress already present in these patients. This study aimed to further clarify the role of repeated intravenous iron therapy as a supplementary cause of oxidative stress in HD patients. Markers of free radical activities (carbonyl reactive derivatives, CRD, thiol groups, SH, malondialdehyde, MDA) and antioxidant enzyme activities (superoxide dismutase, SOD and glutathione peroxidase, GPX) were determined in plasma and red blood cells (RBC) of 19 hemodialysis patients given a total iron dose of 625 mg (ferrogluconat, Ferrlecit, 62.5 mg). Blood samples were taken before the first and after the last dose of iron. Twenty apparently normal subjects served as healthy controls. Before iron treatment, HD patients exhibited increased concentrations of MDA and CRD in plasma and red blood cells, accompanied with impaired antioxidant capacity. All patients responded to iron therapy with a significant increase in their serum ferritin, serum iron, hemoglobin, and red blood cells levels. However, iron treatment resulted in enhanced oxidative stress in plasma of HD patients, since significant increase in plasma MDA and CRD concentrations, together with a decrease in nonprotein SH groups levels were detected. Supplementation with iron did not significantly influence plasma SOD and GPX activities, nor did any of the red blood cell parameters tested. Our data show that, despite improvement in hematological parameters, an increase in iron stores due to supplementation could also contribute to increased free radical production in HD patients.

Physicochemical properties of ferumoxytol, a new intravenous iron preparation

BACKGROUND

Intravenous iron is a critical component of anaemia management. However, currently available preparations have been associated with the release of free iron, a promoter of bacterial growth and oxidative stress.

MATERIALS AND METHODS

We determined the molecular weight, dialysability and capacity for free iron release of ferumoxytol, a semi-synthetic carbohydrate-coated superparamagnetic iron oxide nanoparticle. Ferumoxytol was compared with three intravenous iron preparations in clinical use: iron dextran (low molecular weight), sodium ferric gluconate and iron sucrose. Intravenous iron preparations were also incubated in rat, and pooled human sera (at concentrations of 600 microM and 42 microg mL(-1) respectively) from healthy subjects.

RESULTS

The molecular weight of ferumoxytol was 731 kDa. The relative order of molecular weight was as follows: ferumoxytol > iron dextran > iron sucrose > sodium ferric gluconate. The least ultrafilterable iron was observed with ferumoxytol and the most with ferric gluconate. The least dialysable free iron was observed with ferumoxytol and the most with ferric gluconate. Incubation of intravenous iron preparations in rat or pooled human sera demonstrated minimal free iron release with ferumoxytol. The order of catalytic iron release as detected by the bleomycin detectable iron assay was as follows: ferumoxytol < iron dextran < iron sucrose < ferric gluconate. A similar trend was observed for the in vivo serum concentration of free iron in rats.

CONCLUSIONS

In vitro observations from these experiments suggest that ferumoxytol has a favourable profile in terms of tendency to release free iron, in comparison with currently available intravenous iron preparations.

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.

Parenteral iron use: possible contribution to exceeding target hemoglobin in hemodialysis patients

BACKGROUND AND OBJECTIVES

Use of parenteral iron for anemia management in dialysis patients has greatly increased. Exceeding hemoglobin target levels is not without risk, and whether parenteral iron administration contributes to exceeding targets has not been tested. The authors aimed to determine prevalence of parenteral iron administration and its contribution to exceeding hemoglobin target levels.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The authors performed a retrospective observational study of 149,292 hemodialysis patients using Centers for Medicaid & Medicare Services data. All patients were point prevalent on January 1, 2004; survived through June 30, 2004; had Medicare as primary payer; were treated with erythropoiesis stimulating agents (ESAs); and had valid hemoglobin values in April, May, and June, 2004.

RESULTS

Of the cohort, 58% received parenteral iron; use was more likely among men, whites, younger patients, and patients with end-stage renal disease as a result of diabetes. Age > 75 yr, African American and other races, baseline hemoglobin > 12 g/dl, higher ESA dose, and iron use in months 1 to 4 of the study period were independently associated with the risk of exceeding hemoglobin levels of 12, 13, and 14 g/dl. Receiving iron in month 4 of the study period showed the highest probability of exceeding targets (odds ratios 1.49, 1.43, 1.50 for hemoglobin levels 12, 13, 14 g/dl, respectively).

CONCLUSIONS

Parenteral iron use is prevalent, and although adequate iron stores are central to ESA response, iron use may contribute to exceeding recommended hemoglobin levels. Only data from a prospective trial can confirm this association.

High prevalence of prehypertension is associated with the increased body mass index in community-dwelling Japanese

Hypertension and obesity are likely the most common disease in Japan. It has been reported that subjects with prehypertension (systolic blood pressure [SBP] 120-139 mmHg and/or diastolic blood pressure [DBP] 80-89 mmHg) have also an increased risk of cardiovascular disease; however, only limited data are available on the prevalence of prehypertension and its association with body weight. We performed a cross-sectional study to examine whether the status of body weight was associated with prehypertension. Study participants aged 19 to 90 years [1,207 men aged 60 +/- 15 (mean +/- standard deviation) years and 1,634 women aged 63 +/- 12 years] were randomly recruited for a survey at the community-based annual medical check-up. The prevalence of prehypertension was 27.3% in men and 23.9% in women. The levels of SBP and DBP increased, as body mass index (BMI) increased in both genders. In a multivariate-adjusted model, increasing BMI categories were positively associated with prehypertension. Especially in men, compared to participants with BMI of < 21.0 kg/m(2) (referent), the multivariate-odds ratio (95% CI) of prehypertension was 1.90 (1.17-3.09) in the 21.0-23.4 kg/m(2) group, 2.38 (1.31-4.34) in the 23.5-24.9 kg/m(2) group, and 3.79 (2.03-7.09) in the > or = 25.0 kg/m(2) group. In conclusion, even subjects with mildly increased BMI (21.0-24.9 kg/m(2)) had an increased risk of prehypertension in community-dwelling persons. It is time to pay more attention to excess bodyweight in preventing high blood pressure.

Advanced oxidative protein products are independently associated with endothelial function in peritoneal dialysis patients

AIM

Oxidative stress (OS) and asymmetric dimethylarginine (ADMA) are accepted as non-classical cardiovascular risk factors in end-stage renal disease patients. To clarify the role of these factors in the atherosclerotic process, we investigated if OS and ADMA are associated with endothelial function (EF) in peritoneal dialysis (PD) patients.

METHODS

Fifty-two non-diabetic PD patients without known atherosclerotic disease as well as 30 age- and sex-matched healthy individuals were included. We measured serum thiobarbituric acid-reactive substances (TBARS), malondialdehyde (MDA), advanced glycation end-product (AGE), pentosidine, advanced oxidation protein products (AOPP), ADMA and EF as described by Celermejer et al. in all subjects.

RESULTS

TBARS, MDA, AOPP, AGE, pentosidine and ADMA levels were significantly higher in PD patients than in controls (P < 0.001). Flow-mediated dilatation (FMD)% and nitrate mediated dilatation (NMD)% in PD patients were lower than in the control group (7.7 +/- 4.0% vs 11.70 +/- 5.50%, P < 0.01 and 17.6 +/- 8.3% vs 26.4 +/- 4.6%, P < 0.01). Additionally, it was found that AOPP are independently correlated with FMD% and NMD% in PD patients (beta = -463, P < 0.01 and beta = -420, P < 0.05).

CONCLUSION

This study shows that PD patients without known atherosclerotic disease can also be characterized by endothelial dysfunction and AOPP levels independently predict endothelial function level in PD patients.

CD36 is one of important receptors promoting renal tubular injury by advanced oxidation protein products

Chronic accumulation of plasma advanced oxidation protein products (AOPPs) promotes renal fibrosis. However, the mechanism at the cellular level has not been clarified. In the present study, endocytic assay of human proximal tubular cells (HK-2 cells) demonstrated that AOPPs-human serum albumin (HSA) (in vitro preparations of chloramine- modified HSA) were significantly endocytosed in a dose-dependent manner at a higher level than HSA. The expression of CD36, a transmembrane protein of the class B scavenger receptor, in HK-2 cells was confirmed in the immunoblot analysis. In a cellular assay using overexpressing human CD36 in Chinese hamster ovary (CHO) cells, AOPPs-HSA were significantly endocytosed by CD36-CHO cells but not by mock-CHO cells. Furthermore, the endocytic association and degradation of AOPPs-HSA by HK-2 cells was significantly inhibited by anti-CD36 antibody treatment, suggesting that CD36 is partly involved in the uptake of AOPPs-HSA by HK-2 cells. AOPPs-HSA upregulated the expression of CD36 in a dose-dependent manner. In addition, AOPPs-HSA upregulated the generation of intracellular reactive oxygen species and the secretion of transforming growth factor (TGF)-β1 in HK-2 cells, whereas anti-CD36 antibody neutralizes the upregulation of TGF-β1. These results suggest that AOPPs-HSA may cause renal tubular injury via the CD36 pathway.

Safety issues with intravenous iron products in the management of anemia in chronic kidney disease

Anemia is a very common clinical problem in patients with chronic kidney disease (CKD) and is associated with increased morbidity and mortality in these patients. Erythropoietin is a hormone synthesized that is deficient in the majority of patients with advanced kidney disease, thereby predisposing these patients to anemia. The other cause of anemia is deficiency of iron. Iron deficiency anemia is common in people with CKD and its importance in supporting erythropoiesis is unquestioned, especially in those patients treated with erythropoietin. Intravenous iron is frequently used to treat anemia in CKD patients and is very efficacious in increasing hemoglobin but at the same time there are some safety issues associated with it. The objective of this review is to assess the frequency of adverse drug events associated with four different iron formulations: two iron dextran products known as high and low molecular weight iron dextran, iron sucrose, and sodium ferric gluconate complex. Several electronic databases were searched. In general, with the exception of high molecular weight iron dextran, serious or life-threatening adverse events appeared rare. Iron sucrose has the least reported adverse events and high molecular weight iron dextran has the highest number of reported adverse events. Low molecular weight iron dextran and ferric gluconate fall in between these two for number of adverse drug events.

Serum Ferritin: Deceptively Simple or Simply Deceptive? Lessons Learned From Iron Therapy in Patients With Chronic Kidney Disease

Iron is an essential micronutrient that is indispensable for erythropoesis. Correct assessment of iron stores is needed both for the diagnosis of iron deficiency and to direct iron replacement therapies. Serum ferritin is a commonly employed measure to assess iron stores, yet there are caveats that influence its accuracy as a diagnostic tool. While low ferritin levels are specific for iron deficiency, high levels can be the result of inflammation, liver disease, or malignancies and could be independent of iron stores. Optimal anemia management involves administration of adequate amounts of iron. The right dose of iron that allows optimal erythropoesis yet avoids oxidative stress is a matter of ongoing debate, especially when using imperfect diagnostic tools such as serum ferritin to direct therapy. Data from hemodialysis patients are presented to illustrate the challenges one faces when trying to achieve the best possible therapeutic benefit from iron-replacement therapy.

Advanced oxidation protein products activate vascular endothelial cells via a RAGE-mediated signaling pathway

The accumulation of advanced oxidation protein products (AOPPs) has been linked to vascular lesions in diabetes, chronic renal insufficiency, and atherosclerosis. However, the signaling pathway involved in AOPPs-induced endothelial cells (ECs) perturbation is unknown and was investigated. AOPPs modified human serum albumin (AOPPs-HSA) bound to the receptor for advanced glycation end products (RAGE) in a dose-dependent and saturable manner. AOPPs-HSA competitively inhibited the binding of soluble RAGE (sRAGE) with its preferential ligands advanced glycation end products (AGEs). Incubation of AOPPs, either prepared in vitro or isolated from uremic serum, with human umbilical vein ECs induced superoxide generation, activation of NAD(P)H oxidase, ERK 1/2 and p38, and nuclear translocation of NF-kappaB. Activation of signaling pathway by AOPPs-ECs interaction resulted in overexpression of VCAM-1 and ICAM-1 at both gene and protein levels. This AOPPs-triggered biochemical cascade in ECs was prevented by blocking RAGE with either anti-RAGE IgG or excess sRAGE, but was not affected by the neutralizing anti-AGEs IgG. These data suggested that AOPPs might be new ligands of endothelial RAGE. AOPPs-HSA activates vascular ECs via RAGE-mediated signals.

Intravenous iron exacerbates oxidative DNA damage in peripheral blood lymphocytes in chronic hemodialysis patients

Patients undergoing maintenance hemodialysis have elevated markers of oxidative stress, but the reasons for this are not fully understood. Intravenous administration of iron, which many of these patients receive, may provoke the generation of bioactive iron, which enhances oxidative stress and lipid peroxidation. In this study, 110 hemodialysis patients were randomly assigned to five groups that were administered single intravenous doses of iron sucrose, ranging from 20 to 500 mg. A time- and dosage-dependent rise in lymphocyte 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in lymphocyte DNA, a marker of oxidative DNA damage, with a significant increase at 2 h after intravenous iron of > or = 200 mg (P < 0.05). Four weeks later, patients were randomly assigned to weekly iron sucrose (100 mg of elemental iron) or saline for 12 wk, and 89 patients completed the study. Mean lymphocyte 8-OHdG content was significantly higher in patients receiving intravenous iron compared with control subjects (P < 0.05), especially in those with ferritin levels > 500 microg/L. In addition, flow cytometric techniques revealed increased production of reactive oxygen species in lymphocytes among those treated with intravenous iron. Treatment with intravenous iron but not saline was also associated with decreased plasma ascorbate and alpha-tocopherol levels and increased oxidized glutathione/reduced glutathione ratio (P < 0.05). In summary, intravenous iron sucrose provokes oxidative damage to peripheral blood lymphocyte DNA in hemodialysis patients, especially among those with high levels of ferritin.

Iron, oxidative stress, and clinical outcomes

It is well known that iron is pro-oxidant. Chronic kidney disease (CKD) is a pro-oxidant state, and intravenous administration of iron is frequently used to correct anemia. On one hand, there is little doubt that iron causes oxidative stress. On the other, it is far from clear whether oxidative stress, so generated, leads to poor clinical outcomes. Iron has benefits that may be independent of the correction of anemia. Furthermore, concerns surround the use of high doses of erythropoietin in causing excess heart failure and death in patients with CKD. Thus, it would be prudent if iron were to continue to be used judiciously in patients who require erythropoietin. Iron, given orally, would be the preferred first-line agent in patients not on hemodialysis. In patients with sepsis, intravenous treatment with iron should be avoided, because, in animal experiments, intravenous administration of iron can compound the inflammatory response and increase mortality. Clinical trials are needed to ascertain the risk and benefits of the intravenous administration of iron in patients with CKD.

Anemia and anemia correction: surrogate markers or causes of morbidity in chronic kidney disease?

Observational studies have shown a strong positive correlation between the severity of anemia and the risk of poor outcomes in patients with chronic kidney disease (CKD). This observation was initially taken to imply that adverse outcomes in CKD are caused by anemia. However, the assumption of causality ignores the possibility that anemia and adverse outcomes might be unrelated and that both are caused by underlying inflammation, oxidative stress and comorbid conditions. Randomized clinical trials of anemia correction have revealed an increased risk of adverse cardiovascular outcomes in patients assigned to normal, rather than subnormal, hemoglobin targets. As a result, correction of anemia is now considered potentially hazardous in patients with CKD. Notably, individuals who did not reach the target hemoglobin level in the clinical trials, despite receiving high doses of erythropoietin and iron, experienced a disproportionately large share of the adverse outcomes. These observations point to overdose of erythropoietin and iron, rather than anemia correction per se, as the likely culprit. This Review explores the reasons for the apparent contradiction between the findings of observational studies and randomized clinical trials of anemia treatment in CKD. I have focused on data from basic and translational studies, which are often overlooked in the design and interpretation of clinical studies and in the formulation of clinical guidelines.

Enhanced formation of advanced oxidation protein products in IBD

BACKGROUND

Advanced oxidation protein products (AOPPs) are new protein markers of oxidative stress with pro-inflammatory properties, accumulated in many pathological conditions. The issue of their enhanced formation in IBD has not been addressed yet.

METHODS

The concentration of relative AOPPs (rAOPP; concentration of AOPPs divided by albumin level) were measured in 68 subjects with ulcerative colitis (UC), 50 subjects with Crohn's disease (CD) and 45 healthy volunteers, and related to disease phenotype, clinical and biochemical activity, and therapeutic strategy. Diagnostic utility of rAOPP was evaluated by ROC analysis.

RESULTS

In comparison with controls (1.367 micromol/g), rAOPP were increased in inactive (1.778 micromol/g, P = 0.053) and active (1.895 micromol/g, P = 0.013) UC and in active (1.847 micromol/g, P = 0.003) CD. In CD, but not UC, rAOPP correlated with disease activity (r = 0.42, P = 0.013). Significant correlations with the inflammatory/malnutrition indices-erythrocyte sedimentation rate (ESR) (r = 0.53), leukocytes (r = 0.33), platelets (r = 0.38), IL-6 (r = 0.36), and transferrin (r = -0.35) were demonstrated in CD. In UC, rAOPP correlated only with ESR (r = 0.35) and IL-6 (r = 0.30). Instead, associations with antioxidant dismutase (r = 0.29) and catalase (r = 0.22) were observed. The diagnostic power of rAOPP in discriminating diseased from non-diseased subjects was less than that of C-reactive protein (CRP). Simultaneous determination of rAOPP and CRP did not significantly improve the power of single CRP determination.

CONCLUSIONS

IBD was associated with enhanced formation of AOPP, which differed between C and UC with respect to the relationship between rAOPP and disease activity, inflammatory and antioxidant response. These differences may reflect divergent ways that oxidative stress develops in CD and UC. The diagnostic power of rAOPP was insufficient for its clinical application.

Anemia of Chronic Kidney Disease

Chronic kidney disease may result in complete kidney failure and contribute to many other health issues. Anemia is a logical consequence of the disease because the kidneys are the primary source of erythropoietin, the hormone that acts to stimulate red blood cell production in the bone marrow. All patients with chronic kidney disease are at risk for anemia, and treating anemia is extremely important to their health and well-being. Preventing or reversing the effects of anemia on the heart may decrease morbidity and mortality and improve quality of life. Many patients fail to receive treatment for anemia before requiring renal replacement therapy for end-stage renal disease. Pharmacists can play a vital role in screening, evaluating, designing proper treatment regimens, and monitoring patients with anemia of chronic kidney disease. Current recommendations regarding anemia are reviewed, including evaluation, pharmacotherapeutic agents, monitoring parameters, and goals of therapy.

Associations of isoprostanes-related oxidative stress with surrogate subclinical indices and angiographic measures of atherosclerosis

OBJECTIVES

Cardiovascular diseases are the most common cause of death in the world. Oxidative stress has been proved to play a role in atherosclerotic diseases and 8-isoprostane is one of the most valid markers of in-vivo oxidative stress. We aimed to investigate the 8-isoprostane levels in relation to surrogate and direct angiographic indexes of atherosclerosis.

METHODS

Urinary 8-isoprostane levels were measured and a B-mode carotid ultrasound examination was performed in 100 consecutive patients scheduled for coronary angiography.

RESULTS

In patients with angiographic coronary artery disease (CAD) urinary 8-isoprostane levels were significantly (P<0.001) higher than in patients without CAD (68.75+/-5.5 vs. 38.27+/-3.7 pg/ml). Moreover, 8-isoprostane levels of patients with increased carotid intima media thickness (CIMT) were higher (P<0.001) than in patients with normal CIMT values (75.12+/-6.4 vs. 38.72+/-2.7 pg/ml). Moreover log(8-isoprostane) levels were significantly correlated with maximum and mean CIMT values (P<0.001) and across univessel and multivessel CAD groups levels of log(8-isoprostane) showed a significantly (P<0.001) increasing trend. Logistic regression analysis revealed that 8-isoprostane levels were an independent predictor for both intima-media thickening and angiographic CAD.

CONCLUSION

These findings indicate that elevated urinary levels of 8-isoprostane are associated with both subclinical atherosclerosis and manifest CAD. The results therefore support the hypothesis that isoprostanes-related oxidative stress is involved in the whole atherosclerotic process.

Protective effects of ACE inhibitors on vascular endothelial dysfunction induced by exogenous advanced oxidation protein products in rats

To explore detrimental effects of advanced oxidation protein products-bovine serum albumin (BSA) on endothelial function and compare the favorable effects of angiotensin-converting enzyme (ACE) inhibitors: captopril and enalapril. Male Sprague-Dawley rats were randomly divided into groups: control, advanced oxidation protein products-BSA, captopril (10, 20 mg/kg/day), enalapril (15 mg/kg/day), and N(G)-nitro-l-arginine methyl ester (l-NAME, 300 mg/kg/day) plus captopril (20 mg/kg/day) groups. All animals were given advanced oxidation protein products-BSA (100 mg/kg/day, i.v.) except for control group (iv. equal volume of PBS). Rats in other groups were received different drugs intragastrically after advanced oxidation protein products-BSA administration. Endothelium-dependent relaxation of thoracic aorta was assayed. Content of nitrite/nitrate (NO), malondialdehyde (MDA), activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and of ACE in Sera, as well as renal function index including blood urea nitrogen and creatinine were measured. After 30 days, the endothelium-dependent relaxation of blood vessels in received advanced oxidation protein products-BSA rats was significantly impaired compared with control rats. The impairment was accompanied by decreases of serum NO, activity of GSH-Px and SOD. Administration of captopril and enalapril not only decreased damage of endothelium-dependent relaxation, but also reverse the changes of MDA levels, NO content and activity of SOD. The protective effect of captopril was abolished by L-NAME. Blood urea nitrogen and creatinine had no significant differences between various groups. ACE activities were decreased in high captopril and enalapril groups, but did not significantly change in other groups. The results suggested that captopril and enalapril have similar effects on endothelial dysfunction induced by advanced oxidation protein products-BSA, which indicated that protective effects of captopril are not related to sulfhydryl group.

An association between decreased estimated glomerular filtration rate and arterial stiffness

OBJECTIVE

Chronic kidney disease (CKD) is a major public health problem, but there is controversy over whether or not CKD is an independent risk factor for peripheral arterial stiffness in community residents.

PATIENTS AND METHODS

We randomly recruited 107 men, aged 68+/-9 (mean +/- standard deviation) years, and 203 women, aged 67+/-7 years during their annual health examination in a single community. Study subjects did not have a clinical history of cerebrovascular disease or current neurological abnormalities. Peripheral arterial stiffness was evaluated by mean pulse wave velocity (PWV) determined at three points: from heart to the carotid artery, to the brachial artery, and to the ankle, and CKD was evaluated by estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease Study Group equation.

RESULTS

Estimated GFR was significantly correlated with mean PWV (r=-0.317, p<0.001). Stepwise multiple linear regression analysis using mean PWV as an objective variable, adjusted by explanatory variables, showed that eGFR (beta,-0.171; p<0.001) significantly contributed to mean PWV, along with age, body mass index, systolic blood pressure, diastolic blood pressure, and antihypertensive drug use, and improved multiple coefficient of determination in the model.

CONCLUSION

Decreased eGFR is associated with an increased risk of arterial stiffness in community residents.

An association between the estimated glomerular filtration rate and carotid atherosclerosis

OBJECTIVE

Chronic kidney disease (CKD) is a major public health problem. There is conflicting evidence concerning whether CKD is an independent risk factor for carotid intima-media thickness (IMT).

PATIENTS AND METHODS

The study subjects were 428 men aged 70+/-15 (mean+/-standard deviation) years and 582 women aged 75+/-12 years enrolled consecutively from patients in the Medical Department of Seiyo Municipal Nomura Hospital. Carotid IMT was derived via B-mode ultrasonography and CKD was evaluated by the estimated glomerular filtration rate (eGFR) using the Modification of Diet in Renal Disease Study equation.

RESULTS

In men, age (p<0.001), systolic blood pressure (p<0.001), antihypertensive drug use (p<0.001), HDL-C (p=0.006), LDL-C (p=0.004), prevalence of diabetes (p=0.035) and eGFR (p<0.001) were significantly correlated with carotid IMT. In women, age (p<0.001), systolic blood pressure (p<0.001), antihypertensive drug use (p<0.001), HDL-C (p=0.035), LDL-C (p=0.017) and eGFR (p<0.001) were significantly correlated with carotid IMT. Stepwise multiple linear regression analysis using IMT as an objective variable, adjusted by various factors as explanatory variables, showed that eGFR was a significant independent contributing factor along with known risk factors in men (beta, -0.096; p=0.018) and women (beta, -0.080; p=0.035).

CONCLUSIONS

Our data suggested that eGFR was associated with an increased prevalence of carotid atherosclerosis independent of common cardiovascular risk factors in both men and women.

An association between metabolic syndrome and the estimated glomerular filtration rate

OBJECTIVE

Metabolic syndrome (MetS) is a major public health problem. However, few studies have examined the significance of MetS as a risk factor for the development of chronic kidney disease (CKD) in the general Japanese population.

METHODS

Study participants without a clinical history of stroke, transient ischemic attack, myocardial infarction, angina, or renal failure (1,158 men, aged 61+/-15 years and 1,606 women, aged 63+/-12 years) were recruited from a single community. We examined the cross-sectional relationship between MetS and renal function as evaluated by estimated glomerular filtration rate (eGFR).

RESULTS

The presence of MetS was consistently associated with reduced eGFR, with the level of reduction proportional to the number of MetS components present. Multiple linear regression analysis using eGFR as an objective variable showed that BMI, DBP, antihypertensive drug use, high-density lipoprotein cholesterol, antilipidemic drug use and fasting blood glucose, which were components of MetS, were significantly and independently associated with eGFR, in addition to age and low-density lipoprotein cholesterol. Individuals with MetS showed a multivariate-adjusted odds ratio of 1.53 (95% confidence interval, 1.10-2.13) for CKD compared to those without MetS.

CONCLUSIONS

MetS was significantly associated with decreased eGFR in the general population.

Erythropoiesis-stimulating agent hyporesponsiveness

Approximately 5-10% of patients with chronic kidney disease demonstrate hyporesponsiveness to erythropoiesis-stimulating agents (ESA), defined as a continued need for greater than 300 IU/kg per week erythropoietin or 1.5 mug/kg per week darbepoetin administered by the subcutaneous route. Such hyporesponsiveness contributes significantly to morbidity, mortality and health-care economic burden in chronic kidney disease and represents an important diagnostic and management challenge. The commonest causes of ESA resistance are non-compliance, absolute or functional iron deficiency and inflammation. It is widely accepted that maintaining adequate iron stores, ideally by administering iron parenterally, is the most important strategy for reducing the requirements for, and enhancing the efficacy of ESA. There have been recent epidemiologic studies linking parenteral iron therapy to an increased risk of infection and atherosclerosis, although other investigations have refuted this. Inflammatory ESA hyporesponsiveness has been reported to be improved by a number of interventions, including the use of biocompatible membranes, ultrapure dialysate, transplant nephrectomy, ascorbic acid therapy, vitamin E supplementation, statins and oxpentifylline administration. Other variably well-established causes of ESA hyporesponsiveness include inadequate dialysis, hyperparathyroidism, nutrient deficiencies (vitamin B12, folate, vitamin C, carnitine), angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, aluminium overload, antibody-mediated pure red cell aplasia, primary bone marrow disorders, myelosuppressive agents, haemoglobinopathies, haemolysis and hypersplenism. This paper reviews the causes of ESA hyporesponsiveness and the clinical evidence for proposed therapeutic interventions. A practical algorithm for approaching the investigation and management of patients with ESA hyporesponsiveness is also provided.

Single-dosage pharmacokinetics of sodium ferric gluconate complex in iron-deficient pediatric hemodialysis patients

BACKGROUND AND OBJECTIVES

The clinical use of sodium ferric gluconate complex in iron-deficient pediatric patients receiving hemodialysis was recently approved. This study was designed to describe the pharmacokinetic parameters of the medication.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Iron-deficient pediatric (< or = 15 yr) hemodialysis patients were randomly assigned to two doses (1.5 and 3.0 mg/kg) of sodium ferric gluconate complex. Blood samples taken during a 1-h infusion and at multiple intervals during 48 h were analyzed for total iron, transferrin-bound iron, and sodium ferric gluconate complex-bound iron.

RESULTS

Forty-nine patients (mean age 12.3 +/- 2.5 yr) participated in the study. Mean serum iron concentrations rapidly increased in a dosage-dependent manner. A rapid rise in total serum iron was followed by a slower, less prominent rise in transferrin-bound iron. This was qualitatively confirmed by visualization of the transferrin bands from polyacrylamide gel electrophoresis. Single-dose pharmacokinetics of sodium ferric gluconate complex-bound iron was described using noncompartmental analytical methods. Mean values for the 1.5 mg/Kg dose were as follows: t(1/2) 2.0 +/- 0.7 h, Cmax 1287 mcg/dl, Tmax 1.1 +/- 0.23 h, Cl 0.69 +/- 0.50 L/h, Vd 1.6 +/- 0.6 L, AUC(0-infinity). 9499 +/- 4089 mcg x hr/dl.

CONCLUSIONS

The infusion of sodium ferric gluconate complex to pediatric patients who receive hemodialysis appears to result in a delayed transfer of iron to transferrin, likely after an initial movement through the reticuloendothelial system. Differences noted between the pediatric and adult pharmacokinetic data may result from the unique aspects of the study populations and the respective study designs.

Mechanism of increased mortality risk with erythropoietin treatment to higher hemoglobin targets

Recent randomized, controlled trials indicate that there is a strong trend for increased risk for death or adverse composite outcomes with erythropoiesis-stimulating agent treatment in kidney disease to hemoglobin targets higher than those currently recommended. The failure of these trials to find a benefit of higher hemoglobin is in stark contrast to findings from large, observational, population-based studies that continue to demonstrate the association of low hemoglobin with adverse outcomes. The mechanisms for the adverse effect of higher hemoglobin targets that are seen in the randomized, controlled trials are poorly understood. This review explores hypotheses involving (1) the effect of achieved hemoglobin itself, (2) the role of erythropoiesis-stimulating agent treatment, (3) the use of iron supplementation, (4) increased blood pressure, and (5) erythropoiesis-stimulating agent hyporesponsiveness. Because the causal pathway has yet to be determined, further research is strongly encouraged. Clinical practice, however, should avoid erythropoiesis-stimulating agent treatment to higher hemoglobin targets, particularly in those with significant cardiovascular morbidity and those who require disproportionately high dosages of erythropoietin-stimulating agents to achieve recommended hemoglobin levels.

Dietary iron intake and serum ferritin in relation to 7.5 years structure and function of large arteries in the SUVIMAX cohort

AIM

Few studies have investigated the relationship between iron stores and measures of atherosclerosis. Most of these studies were cross-sectional and yielded conflicting results. We aimed to assess the relationship between serum ferritin concentrations and dietary iron intake measured at baseline and 7.5 year pulse wave velocity (PWV), intima-media thickness (IMT) and plaques in a group of 824 men and women without known CVD, cancer or hemochromatosis.

METHODS

The SUVIMAX study is a randomized double-blind, placebo-controlled primary prevention trial designed to test the effect of antioxidant supplementation in reducing ischemic cardiovascular diseases and cancer.

RESULTS

In multivariate analyses, no association was found between baseline serum ferritin levels and IMT 7 years later (beta (95% CI)=0.003 (-0.005;0.011) in men; -0.005 (-0.013;0.004) and -0.001 (-0.011;0.009) in women, before and after menopause, respectively), plaques (OR (95% CI)=1.09 (0.88;1.34) in men; 0.93 (0.66;1.31) and 0.95 (0.70;1.29) in women, before and after menopause, respectively) or PWV (beta (95% CI)=0.078 (-0.154;0.310) in men; -0.018 (-0266;0.231) in women before and after menopause). Results for dietary iron intake were similar.

CONCLUSION

Our results do not support the hypothesis that dietary iron intake and body iron stores are deleterious to the structure and function of large arteries in subjects free of CVD, cancer or hemochromatosis.

The fascinating but deceptive ferritin: to measure it or not to measure it in chronic kidney disease?

Although the emergence of erythropoiesis-stimulating agents has revolutionized the anemia management of chronic kidney disease (CKD) in the past two decades, strategies to assess iron (Fe) status and to provide Fe supplementation have remained indistinct. The reported cases of hemochromatosis in dialysis patients from the pre-erythropoiesis-stimulating agent era along with the possible associations of Fe with infection and oxidative stress have fueled the "iron apprehension." To date, no reliable marker of Fe stores in CKD has been agreed on. Serum ferritin continues to be the focus of attention. Almost half of all maintenance hemodialysis patients have a serum ferritin >500 ng/ml. In this ferritin range, Fe supplementation currently is not encouraged, although most reported hemochromatosis cases had a serum ferritin >2000 ng/ml. The moderate-range hyperferritinemia (500 to 2000 ng/ml) seems to be due mostly to non-Fe-related conditions, including inflammation, malnutrition, liver disease, infection, and malignancy. Recent epidemiologic studies have shown that a low, rather than a high, serum Fe is associated with a poor survival in maintenance hemodialysis patients. In multivariate adjusted models that mitigate the confounding effect of malnutrition-inflammation, serum ferritin <1200 ng/ml and Fe saturation ratio in 30 to 50% range are associated with the greatest survival in maintenance hemodialysis patients. Although ferritin is a fascinating molecule, moderate hyperferritinemia is a misleading marker of Fe stores in patients with CKD. It may be time to revisit the utility of serum ferritin in CKD and ask ourselves whether its measurement has helped us or has caused more confusion and controversy.

Acute injury with intravenous iron and concerns regarding long-term safety

Intravenous iron is widely used to maintain adequate iron stores and prevent iron deficiency anemia in patients with chronic kidney disease, yet concerns remain about its long-term safety with respect to oxidative stress, kidney injury, and accelerated atherosclerosis, which are the subjects of this review. Three parenteral iron formulations are available for use in the United States: Iron dextran, iron gluconate, and iron sucrose. Iron dextran, especially the high molecular form, has been linked with anaphylactoid and anaphylactic reactions, and its use has been declining. A portion of intravenous iron preparations is redox-active, labile iron available for direct donation to transferrin. In vitro tests show that commonly available intravenous iron formulations have differing capacities to saturate transferrin directly: Iron gluconate > iron sucrose > iron dextran. Intravenous iron treatment produces oxidative stress, as demonstrated by increases in plasma levels of lipid peroxidation products (malondialdehyde), at a point that is much earlier than the time to peak concentration of catalytically active iron, suggesting a direct effect of iron sucrose on oxidative stress. Furthermore, iron sucrose infusion produces endothelial dysfunction that seems to peak earlier than the serum level of free iron. Intravenous iron sucrose infusion also has been shown to produce acute renal injury and inflammation as demonstrated by increased urinary albumin, enzyme (N-acetyl-beta-glucosaminidase), and cytokine (chemokine monocyte chemoattractant protein-1) excretions. Although the long-term dangers of intravenous iron are unproved, these data call for examination of effects of intravenous iron on the potential for long-term harm in patients with chronic kidney disease.

Slow intravenous iron administration does not aggravate oxidative stress and inflammatory biomarkers during hemodialysis: a comparative study between iron sucrose and iron dextran

BACKGROUND/AIMS

Fast intravenous (i.v.) iron administration during hemodialysis (HD) is associated with the augmentation of oxidative stress and the increase in inflammatory biomarkers, which are also induced by the hemodialysis procedure itself. The aim of this study was to investigate if slow i.v. iron administration would aggravate the status of oxidative stress and inflammatory biomarkers during a hemodialysis session.

METHODS

Twenty dialysis patients 30-92 years of age that were iron replete and had values for hemoglobin, transferrin saturation and serum ferritin among recommended goals were evaluated in three separate hemodialysis sessions. In the first session patients did not receive any iron treatment, whereas during the second and the third session patients received slow (60 min) i.v. infusions of 100 mg of iron sucrose and 100 mg of iron dextran, respectively. Blood samples were drawn before the hemodialysis session, 15 min after the end of iron administration and at the end of the hemodialysis session in all occasions, for the measurement of markers of oxidant stress (oxidized LDL and ischemia-modified albumin) and inflammation (high-sensitivity C-reactive protein, interleukin-6 and tumor necrosis factor-alpha).

RESULTS

Oxidized LDL was not significantly altered during hemodialysis and this pattern was similar between the three occasions studied. In contrast, ischemia-modified albumin was significantly increased and this effect was also not different between the net hemodialysis and the occasions of iron administration. High-sensitivity CRP, IL-6 and TNF-alpha were all significantly elevated during hemodialysis and again both types of iron administration did not produce significant changes in this pattern.

CONCLUSION

We did not find an increase in the markers of oxidation/inflammation studied, after slow i.v. iron administration during hemodialysis session.

Antihypertensive agents and arterial stiffness: relevance to reducing cardiovascular risk in the chronic kidney disease patient

PURPOSE OF REVIEW

Arterial stiffness is a sign of diffuse adventitial macrovascular disease. The purpose of the present review is to discuss, in patients with chronic kidney disease, the pathophysiology of increased arterial stiffness, the role of antihypertensive therapy on reduction of arterial stiffness, and the clinical ways by which the prognostication of cardiovascular disease in patients with chronic kidney disease can be refined using arterial stiffness monitoring.

RECENT FINDINGS

Arterial stiffness is increased with increasing prevalence of traditional cardiovascular risk factors. In patients with chronic kidney disease some unique factors further increase the risk of arterial stiffness, and include volume overload, activation of the renin-angiotensin system, anemia, and dysregulated mineral metabolism. Arterial stiffness is increased even in patients with early-stage chronic kidney disease. Blood pressure reduction when accompanied by a reduction in arterial stiffness is associated with improved prognosis. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers can preferentially improve arterial stiffness, which may be an additional mechanism of cardiovascular protection with these agents.

SUMMARY

The impact of improvement in arterial stiffness with antihypertensive agents on cardiovascular outcomes needs well designed clinical trials.

The plasma concentration of advanced oxidation protein products and arterial stiffness in apparently healthy adults

BACKGROUND

Oxidative stress plays an important role in the pathogenesis of atherosclerosis. Advanced oxidation protein products (AOPP) are markers of oxidative stress and mediators of inflammation. Increased arterial stiffness is associated with increased risk of cardiovascular mortality and morbidity. The aim of this study was to evaluate the relationship between an indirect marker of arterial stiffness and the AOPP level in apparently healthy individuals.

METHODS AND RESULTS

Arterial stiffness was estimated with the use of the stiffness index (SI(DVP)) which significantly correlated with age, mean blood pressure, body fat content and AOPP. The SI(DVP) was associated with AOPP concentration in both single (R = 0.22, p = 0.03) and multiple regression models adjusted for age, sex, mean blood pressure and body fat content (R(2) = 42%, p < 0.0001).

CONCLUSIONS

The AOPP concentration is elevated in healthy people with increased values of stiffness index. This finding supports the concept that oxidative stress may contribute to arterial stiffening in humans.

Metabolic syndrome in HD patients: association with body composition, nutritional status, inflammation and serum iron

OBJECTIVE

Insulin resistance and metabolic syndrome (MeS) are common in end-stage renal disease (ESRD) patients on maintenance hemodialysis (HD). Such metabolic and clinical abnormalities may lead to an increased risk for cardiovascular disease.

METHODS

The study group included 22 well-nourished and 20 middle- to moderate-malnourished, stable ESRD patients, with median dialysis duration of 48 months (IQR 24.5-82.0). To determine nutritional status, body composition, inflammatory biomarkers and the presence of MeS subjective global assessment (SGA), anthropometrical measurements (BMI and waist circumference), bioelectrical impedance analysis (BIA), and biochemical parameters [the levels of serum albumin, cholesterol, HDL-cholesterol, triglyceride, hematocrit, hemoglobin, iron, TIBC, transferrin saturation (TSAT), ferritin, calcium, phosphorus, intact parathormone (i-PTH), TNF-alpha, IL-6 and high sensitivity C-reactive protein (hs-CRP)] were used. All parameters were evaluated by comparisons between two groups, with MeS (Group 2) and without it (Group 1). Logistical regression analysis was used to evaluate the correlation between measured variables and the presence of MeS in HD patients. Independent variables for MeS were identified by backward multivariate regression analysis. To identify the independent predictors for insulin resistance index (HOMA-IR) multivariate regression analysis was conducted, after linear regression analysis.

RESULTS

After adjustment for confounding variables, a model consisting of serum levels of iron, transferrin saturation (TSAT), and BMI which accounted for 62% of the variance in MeS, determined only BMI as an independent marker (according to ATP-III criteria). But, serum glucose level, iron, waist and total fat mass accounted for 68% of the variance in MeS, according to IDF criteria. Glucose level was an independent predictor. BMI and iron, as independent variables, contributed to 29% of the variance in IR HOMA, the sensitive marker of MeS.

CONCLUSION

The present study demonstrated that serum iron participated together with independent predictors, glucose and BMI, in the pathogenesis of IR and MeS of ESRD patients on maintenance HD.

The new FDA label for erythropoietin treatment: how does it affect hemoglobin target?

The erythropoietin analogs have been an important advance for the treatment of the anemia of kidney disease, resulting in reduced need for blood transfusion and improved quality of life. Recent studies, however, have indicated risks associated with targeting higher levels of hemoglobin (Hb). As a result, in March 2007, the US Food and Drug Administration (FDA) substantially changed prescribing information for these drugs to alert clinicians to these risks. In this review, we consider the recent literature, the change in FDA warnings, and new National Kidney Foundation Anemia Guidelines. Suggestions for new Hb targets during erythropoiesis-stimulating agent treatment are presented.

Anemia and heart failure: a cause of progression or only a consequence?

Anemia is one of the most frequent co-morbidities in the patients with heart failure. Its prevalence increases from 4-7% in the subjects with asymptomatic left ventricular dysfunction to >30% in the patients with severe heart failure. Renal insufficiency, activation of inflammatory mediators, and treatment with renin-angiotensin antagonists seem to be its main determinants. The results of many studies agree in showing that anemia is a powerful independent determinant of survival in patients with heart failure. However, the mechanisms of this relation are still incompletely understood. Moreover a favourable effect on prognosis of the correction of anemia has not been shown, yet, and also controlled studies assessing its effects on exercise tolerance have yielded controversial results.

Intravenous versus Oral Iron Supplementation in Peritoneal Dialysis Patients

Iron supplementation is required in a preponderance of peritoneal dialysis (PD) patients treated with erythropoietic stimulatory agents (ESAs). Although many authors and clinical practice guidelines recommend primary oral iron supplementation in ESA-treated PD patients, numerous studies have clearly demonstrated that, because of a combination of poor bioavailability of oral iron, gastrointestinal intolerance, and noncompliance, oral iron supplementation is insufficient for maintaining a positive iron balance in these patients over time. Controlled trials have demonstrated that, in iron-deficient and iron-replete PD patients alike, intravenous (IV) iron supplementation results in superior iron stores and hemoglobin levels with fewer side effects than oral iron produces. Careful monitoring of iron stores in patients receiving IV iron supplementation is important in view of conflicting epidemiologic links between IV iron loading and infection and cardiovascular disease. Emerging new iron therapies such as heme iron polypeptide and ferumoxytol may further enhance the tolerability, efficacy, and ease of administration of iron in PD patients.

Role of oral iron in the management of long-term hemodialysis patients

BACKGROUND

The literature contends that oral iron supplementation is relatively ineffective in patients who are on long-term hemodialysis (HD), and intravenous iron is the superior form of supplementation.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Data were prospectively abstracted from a cross-sectional cohort of all patients in the long-term in-center HD program at St. Michael's Hospital (SMH) from April 1, 2003, to April 1, 2004. Laboratory data were measured monthly. SMH data were compared with those in eight other centers in the Toronto Region Dialysis Registry.

RESULTS

A total of 93% of the 151 patients tolerated oral iron. Eighty-eight (58%) patients received oral iron exclusively, and 60 (40%) patients received intravenous iron with or without oral iron. Of the patients who received oral iron exclusively, 73% maintained a hemoglobin of > or =110 g/L and 93% maintained a hemoglobin of > or =100 g/L. A total of 74% had an iron saturation > or =20%, and 36% had a ferritin level >100 g/L. Among the patients who were on oral iron alone and had hemoglobin of > or =110 g/L, the same amount of erythropoietin was used regardless of ferritin levels (P = 0.17), but less erythropoietin was used when they reached the target for either iron saturation or both iron indices (P = 0.02 and 0.03, respectively). Among the centers in the Toronto Region Dialysis Registry, hemoglobin levels and erythropoietin dosages did not differ among the three centers that predominantly used oral iron versus the six centers that predominantly use intravenous iron (P = 0.46 and 0.95, respectively).

CONCLUSIONS

Oral iron is a well-tolerated and effective form of iron supplementation in long-term HD patients.

HFE gene mutations and oxidative stress influence serum ferritin, associated with vascular damage, in hemodialysis patients

BACKGROUND/AIMS

Hyperferritinemia has been associated with cardiovascular mortality in hemodialysis patients. The aim of this study was to evaluate whether serum ferritin was affected by iron and oxidative status and by genetic factors (HFE mutations and the Ala9Val MnSOD polymorphism), and to assess the association between ferritin and cardiovascular damage evaluated by ecocolor-Doppler.

METHODS

63 hemodialysis patients were tested for HFE and MnSOD genotype by restriction analysis and oxidative status; vascular damage was assessed by measuring intima-media thickness, and by detecting plaques at carotid and femoral arteries.

RESULTS

Ferritin was correlated with transferrin saturation (p = 0.003), decreased iron-specific serum antioxidant activity (p = 0.01), age (p = 0.03), and C282Y and H63D HFE mutations (p = 0.05), but not with the MnSOD polymorphism. Ferritin was associated with advanced vascular damage, as evaluated by the presence of plaques, both at carotid (p = 0.03) and femoral arteries (p = 0.001), the other risk factors being age and low albumin. Low iron-specific antioxidant activity was associated with carotid plaques (p = 0.03).

CONCLUSION

In hemodialysis patients, hyperferritinemia reflects a relative increase in iron availability and a decrease in iron-specific antioxidant activity, is favored by HFE mutations, and represents a risk factor for advanced cardiovascular damage.