Aluminium and lead abnormalities in children on haemodialysis: relationship with some medications

Increased Serum Al Levels in Hemodialysis Patients Kept Enhanced during a 2-Year Prospective Study

The regulation of mineral homeostasis is altered in hemodialysis patients with renal insufficiency, producing increased risk for secondary diseases like cardiovascular ones. We hypothesized that risen serum aluminum (Al) concentration in hemodialysis patients kept enhanced during a 2-year longitudinal study is associated with enhanced cardiovascular risk and influenced by medical treatments. This study reports the prospective monitoring of serum Al levels in six-monthly samplings over 2 years in 116 hemodialysis patients and a control group of 50 healthy adults. The influence of other factors like sex, age, kidney transplant, disease etiology, and drug consumption was also considered. At each sampling, serum Al levels were significantly higher in the patients than in the healthy controls (P < 0.05). Levels in the patient group were statistically significantly lower at the third and fourth versus first and second samplings, which may be related to Al accumulation in tissues. Increased Al levels in patients were positively and significantly related to serum calcium (Ca) and uric acid levels. Serum Al concentrations were significantly lower in patients receiving vasodilators and diuretics. Higher serum Al levels in hemodialyzed patients administered with phosphate binders or anti-hyperkalemics are attributable to their usual Al salt content. The consumption of antianemic drugs increases Al absorption by forming more bioavailable complexes with the compounds in these drugs. In conclusion, this is the first study to indicate that cardiovascular problems associated with elevated serum Al levels in hemodialysis patients may be in part mitigated by administrating vasodilators and diuretics, which reduce these levels.

Negative Relationship between Erythropoietin Dose and Blood Lead Level in Patients Undergoing Maintenance Hemodialysis

The adverse effects of increased blood lead levels have been well discussed. Several antioxidant agents have been reported to offer protection from lead toxicity and to reduce blood lead levels (BLL). Given that erythropoietin (EPO) also has antioxidant properties, the aim of this cross-sectional study was to assess the role of EPO and other clinical variables on BLL in hemodialysis (HD) patients. We recruited 931 maintenance hemodialysis (MHD) patients who had undergone HD for at least 6 months and who had ever received blood lead level (BLL) study. Use of erythropoiesis-stimulating agents followed the The National Kidney Foundation Kidney Disease Outcomes Quality Initiative (NKF KDOQI) Clinical Practice Guideline. We estimated demographic, hematological, nutritional, inflammatory, biochemical, and dialysis-related data based on this study. In the group with EPO, 7% had high BLL. In the group without EPO, 22% had high BLL. From the stepwise liner regression, urban areas, hemodialysis duration, and clearance of urea (KT/V_urea) were positively associated with log BLL. In contrast, diabetes (DM), and monthly EPO dose were negatively associated with log BLL. This study showed that EPO dose might be negatively associated with blood lead levels in patients on maintenance hemodialysis.

Impact of dialyzer membrane flux on metal clearance in hemodialysis patients

Deficiency of essential trace elements (such as Cu or Zn) and accumulation of potentially toxic trace elements (as Cd or Pb) are both known to have adverse effects in hemodialysis (HD) patients. Up to our knowledge, no studies about the permeability of low and high flux polysulfone membranes on metal ions during hemodialysis are available. Therefore, the aim of the present study was to address this issue. Forty one hemodialysis patients (19 were using high flux polysulfone membrane while the remaining were using low flux one) participated in the study. Blood levels of Cu, Zn, Cd and Pb were determined by graphite furnace atomic absorption spectrometry among HD patients, before and after dialysis session, as well as among matched 40 healthy persons. Blood concentrations of Cu and Zn in the whole hemodialysis group was significantly lower than those of the healthy control group, on the other hand the toxic metals (Cd and Pb) levels were observed to be significantly higher among HD patients compared to the normal persons. Among the hemodialysis group, there were no significant differences between the low and high flux dialyzer groups in terms of pre-dialysis blood levels of Cu, Zn, Cd and Pb. In addition, significantly decreased levels of all metal ions were observed after dialysis sessions using either low or high flux membranes. An exception was Pb which did not show any difference between pre-dialysis and post-dialysis values in the low flux groupIn conclusion Zn and Cu deficiencies should be considered in the treatment of these patients. High flux membranes are more efficient than low flux ones in removing excess Cd and Pb. Therefore, when high flux membranes are used, chelation therapy might not be required for Cd and Pb overload.

Systematic review of potential health risks posed by pharmaceutical, occupational and consumer exposures to metallic and nanoscale aluminum, aluminum oxides, aluminum hydroxide and its soluble salts

Abstract Aluminum (Al) is a ubiquitous substance encountered both naturally (as the third most abundant element) and intentionally (used in water, foods, pharmaceuticals, and vaccines); it is also present in ambient and occupational airborne particulates. Existing data underscore the importance of Al physical and chemical forms in relation to its uptake, accumulation, and systemic bioavailability. The present review represents a systematic examination of the peer-reviewed literature on the adverse health effects of Al materials published since a previous critical evaluation compiled by Krewski et al. (2007) . Challenges encountered in carrying out the present review reflected the experimental use of different physical and chemical Al forms, different routes of administration, and different target organs in relation to the magnitude, frequency, and duration of exposure. Wide variations in diet can result in Al intakes that are often higher than the World Health Organization provisional tolerable weekly intake (PTWI), which is based on studies with Al citrate. Comparing daily dietary Al exposures on the basis of "total Al"assumes that gastrointestinal bioavailability for all dietary Al forms is equivalent to that for Al citrate, an approach that requires validation. Current occupational exposure limits (OELs) for identical Al substances vary as much as 15-fold. The toxicity of different Al forms depends in large measure on their physical behavior and relative solubility in water. The toxicity of soluble Al forms depends upon the delivered dose of Al(+3) to target tissues. Trivalent Al reacts with water to produce bidentate superoxide coordination spheres [Al(O2)(H2O4)(+2) and Al(H2O)6 (+3)] that after complexation with O2(•-), generate Al superoxides [Al(O2(•))](H2O5)](+2). Semireduced AlO2(•) radicals deplete mitochondrial Fe and promote generation of H2O2, O2 (•-) and OH(•). Thus, it is the Al(+3)-induced formation of oxygen radicals that accounts for the oxidative damage that leads to intrinsic apoptosis. In contrast, the toxicity of the insoluble Al oxides depends primarily on their behavior as particulates. Aluminum has been held responsible for human morbidity and mortality, but there is no consistent and convincing evidence to associate the Al found in food and drinking water at the doses and chemical forms presently consumed by people living in North America and Western Europe with increased risk for Alzheimer's disease (AD). Neither is there clear evidence to show use of Al-containing underarm antiperspirants or cosmetics increases the risk of AD or breast cancer. Metallic Al, its oxides, and common Al salts have not been shown to be either genotoxic or carcinogenic. Aluminum exposures during neonatal and pediatric parenteral nutrition (PN) can impair bone mineralization and delay neurological development. Adverse effects to vaccines with Al adjuvants have occurred; however, recent controlled trials found that the immunologic response to certain vaccines with Al adjuvants was no greater, and in some cases less than, that after identical vaccination without Al adjuvants. The scientific literature on the adverse health effects of Al is extensive. Health risk assessments for Al must take into account individual co-factors (e.g., age, renal function, diet, gastric pH). Conclusions from the current review point to the need for refinement of the PTWI, reduction of Al contamination in PN solutions, justification for routine addition of Al to vaccines, and harmonization of OELs for Al substances.

Erythropoietin update 2011

Traditionally, erythropoietin (EPO) is described as a hematopoietic cytokine, regulating proliferation and differentiation and survival of the erythroid progenitors. The recent finding of new sites of EPO production and the wide spread distribution of EPO receptors (EPO-R) on endothelial cells, cardiomyocytes, renal cells as well as the central and peripheral nervous system raised the possibility that EPO may exert pleiotropic actions on several targets. Indeed studies (mainly preclinical) have documented protective, non-hematopoietic, abilities of EPO in a variety of tissue. However, the data obtained from clinical studies are more skeptical about these properties. This article provides a comprehensive overview of EPO and its derivatives.