Intravenous iron therapy as a possible risk factor for atherosclerosis in end-stage renal disease

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.

A one-year study of the antiatherosclerotic effect of the angiotensin-II receptor blocker losartan in hypertensive patients. A comparison with angiotension-converting enzyme inhibitors

Angiotensin receptor blockers (ARB) have been emerging as drugs to treat atherosclerosis. The effectiveness of the ARB losartan at reducing atherosclerosis was compared with that of ACE inhibitors in hypertensive patients. A total of 50 patients with hypertension were divided into 3 groups: a control group receiving neither an ARB nor an ACE inhibitor (n = 14), a losartan group (n = 22) receiving 50 mg/day of losartan, and an ACE inhibitor group (n = 14) receiving either 5 mg/day of enalapril or 5 mg/day of imidapril. Atherosclerosis was evaluated based on the intima-media thickness (IMT) of the common carotid artery measured by B-mode ultrasound at baseline and after approximately 12 months of treatment. After the treatment, IMT significantly decreased with losartan (from 0.87 +/- 0.14 to 0.79 +/- 0.16 mm, P < 0.05) and with ACE inhibitor (from 0.81 +/- 0.14 to 0.74 +/- 0.11 mm, P < 0.05). The reduction was comparable between the two groups, -0.078 +/- 0.136 with losartan and -0.073 +/- 0.109 mm with ACE inhibitor, and the rate of the reduction was similar between the two drugs; -0.098 +/- 0.142 mm/year with losartan and (-0.076 +/- 0.118 mm/year) with ACE inhibitor. On the contrary, IMT did not change in the control group (from 0.90 +/- 0.20 to 0.95 +/- 0.26 mm) during the treatment period. Concomitant medication and coronary risk factors such as hyperlipidemia, diabetes mellitus, and smoking did not differ significantly among the groups. The antiatherosclerotic effect of losartan on the carotid artery was comparable to that of ACE-inhibitors, and less adverse effects, such as coughing that occurs with ACE inhibitors, were observed. Losartan appears to be a better alternative to ACE inhibitors for treating atherosclerosis in Japanese hypertensive patients.

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.

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.

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.

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.

Intravenous iron therapy in end-stage renal disease

Intravenous iron therapy is instrumental in the management of anemia in patients with end-stage renal disease (ESRD). Iron is available in several different preparations, with slight differences in the pharmacology of each. Given the importance of intravenous iron in the management of these patients, clinicians should be aware of the potential risks associated with it. Intravenous iron has effects on host immunity that raise concerns about clinical infection risk. Iron preparations appear to increase oxidative stress in these patients, which has important implications for cardiovascular disease states. Lastly, the effects of intravenous iron on liver disease are largely unknown.

Impact of iron sucrose therapy on leucocyte surface molecules and reactive oxygen species in haemodialysis patients

BACKGROUND

It has been suggested that iron increases oxidative stress and that an excess of iron contributes to cardiovascular disease and infections in haemodialysis patients. In the present study, the effects of parenterally administered iron on leucocyte surface molecule expression and the production of reactive oxygen species (ROS) were evaluated.

METHODS

Ten chronic haemodialysis (HD) patients without iron overload were studied. To each patient, four different regimens were applied: placebo; iron sucrose, either 30 or 100 mg, administered via the outflow dialyser line; and 100 mg of iron sucrose infused via the inflow dialyser line. Blood was sampled at different time points: before, during and after infusion and immediately before the next dialysis session. Levels of CD11b and CD45 expression on granulocytes and of CD11b, CD14 and CD36 on monocytes were determined using flow cytometric analysis. The generation of ROS was quantified using chemiluminescence with and without ex vivo stimulation by phorbol myristate acetate (PMA).

RESULTS

No significant differences among the four different treatment regimes were found, neither in chemilumescence activity nor in the expression of CD11b and CD45 on granulocytes, and of CD11b, CD14 and CD36 on monocytes.

CONCLUSIONS

Our results suggest that parenteral infusion of iron sucrose during haemodialysis in patients who have no signs of iron overload has no significant effect on the expression of leucocyte surface molecules and does not increase production of ROS.