silicon and Kidney-Failure--Chronic

The development of wearable or implantable technologies that replace center-based hemodialysis (HD) hold promise to improve outcomes and quality of life for patients with ESRD. A prerequisite for these technologies is the development of highly efficient membranes that can achieve high toxin clearance in small-device formats. Here we examine the application of the porous nanocrystalline silicon (pnc-Si) to HD. pnc-Si is a molecularly thin nanoporous membrane material that is orders of magnitude more permeable than conventional HD membranes. Material developments have allowed us to dramatically increase the amount of active membrane available for dialysis on pnc-Si chips. By controlling pore sizes during manufacturing, pnc-Si membranes can be engineered to pass middle-molecular-weight protein toxins while retaining albumin, mimicking the healthy kidney. A microfluidic dialysis device developed with pnc-Si achieves urea clearance rates that confirm that the membrane offers no resistance to urea passage. Finally, surface modifications with thin hydrophilic coatings are shown to block cell and protein adhesion.

Topics: Humans; Kidney Failure, Chronic; Membranes, Artificial; Microfluidics; Nanopores; Renal Dialysis; Silicon

Recently, new approaches for miniaturization and transportability of medical devices have been developed, paving the way for wearability and the possibility of implantation, for renal replacement therapies. A wearable artificial kidney (WAK) is a medical device that supports renal function during ambulation or social activities out of hospital. With the aim of improving dialysis patients' quality of life, WAK systems have been developed for several decades. However, at present there are a lot of technical issues confronting the attempt to apply WAK systems in clinical practice. This article focuses on technical requirements and potential solutions for WAKs and reviews up-to-date approaches related to dialysis membrane, dialysate regeneration, vascular access, patient-monitoring systems and power sources for WAKs.

Topics: Adsorption; Equipment and Supplies; Equipment Design; Humans; Kidney Failure, Chronic; Kidneys, Artificial; Microscopy, Electron, Scanning; Miniaturization; Monitoring, Ambulatory; Nanoparticles; Quality of Life; Renal Replacement Therapy; Silicon; Solutions; Ultrafiltration

Most of the 400,000+ patients in the United States with kidney failure depend on dialysis treatments in dedicated dialysis centers for 3 h to 5 h, usually 3 times a week, but they still suffer from accelerated cardiovascular disease and infections. Extended daily dialysis, for 6 to 8 hours every day, seems to be associated with better outcomes but would overwhelm the dialysis networks and severely limit patient activity. Technology to miniaturize and automate home dialysis will be necessary to offer extended daily dialysis to most dialysis patients. Miniaturization of existing hollow-fiber polymer membranes is constrained by requirements for high driving pressures for circulation and convective clearance. Recent advances in membrane technology based on microelectromechanical systems (MEMS) promise to enable the development of continuous implantable renal replacement therapy. Silicon nanoporous membranes with a highly monodisperse pore size distribution have been produced using protocols amenable to low-cost batch fabrication similar to those used to produce microelectronics. Hydraulic permeability of the flat-sheet membranes with critical pore sizes in the range of 8-100 nm has been measured to confirm that conventional fluid transport models are sufficiently accurate for predictive design for bulk liquid flow in an implantable hemofilter. Membrane biocompatibility was tested in vitro with human proximal tubule cells and revealed that silicon does not exhibit cytotoxicity, as evidenced by the formation of confluent cell layers with tight junctions and central cilia. Filtration characterization demonstrated that the nanoporous membranes exhibit size-dependent solute rejection in agreement with steric hindrance models. These advances in membrane technology are fundamentally enabling for a paradigm shift from an in-center to implantable dialysis system.

Topics: Biocompatible Materials; Cell Culture Techniques; Dialysis Solutions; Equipment Design; Forecasting; Hemofiltration; Humans; Kidney Failure, Chronic; Kidney Tubules; Kidneys, Artificial; Materials Testing; Membranes, Artificial; Nanotechnology; Prostheses and Implants; Renal Dialysis; Renal Replacement Therapy; Silicon; United States; Uremia

In dialysis patients both aluminum (AI) and silicon (Si) may accumulate. Whereas the toxic effects of AI within this population are clearly established, little is known on the role of Si in the development/protection of particular dialysis-related diseases. A clear insight in the protein binding and speciation of trace elements is important to better understand the mechanisms underlying their toxicity/essentiality. Research in this field however is complex and often prone to analytical difficulties and inaccuracies.. In the first part of this review techniques used for speciation studies of AI and Si in biological fluids are discussed. Notwithstanding recent technical advances (a) extraneous metal contamination, (b) unrecognized aspecific binding of metals to proteins, and (c) unwanted interactions with separation equipment such as chromatography columns and ultrafiltration membranes remain important pitfalls and often lead to erroneous conclusions. The factors that determine the speciation of AI and Si and their ultimate tissue distribution and toxicity are dealt with in the second part. Here, experimental data obtained with various speciation techniques are linked to in vivo data on the tissue distribution, localization/toxicity of both elements.. A model in which the AI tissue distribution/toxicity is mediated by either its citrate or transferrin bound form is proposed.

Topics: Aluminum; Animals; Humans; Kidney Failure, Chronic; Renal Dialysis; Silicon

Two dialysis patients with markedly elevated plasma silicon (Si) levels (3,849 and 2,350 micrograms/l, respectively) and a presumed Si-related syndrome are described in this report. One patient presented with transient hypercalcemia in the face of low PTH, vitamin D and plasma A1 levels. Both patients had painful, nodular skin eruptions and aberrant hair growth, characterized as perforating folliculitis on skin biopsy, compatible with known effects of organosilicon compounds in man and animals. Plasma Si was found to be moderately elevated in 30 dialysis patients studied at random (710 +/- 53 micrograms/l, dialysis, vs. 152 +/- 9 micrograms/l, normal control), but there was no significant difference between the arterial values before and after dialysis, implying that the source of Si was ingested foods and fluids rather than dialysate. In these patients, plasma Si was weakly correlated with serum calcium as well as with serum calcium corrected for serum albumen, indicating that Si, like aluminum, may affect calcium metabolism.

Topics: Adult; Aged; Aged, 80 and over; Aluminum; Drug Eruptions; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Minerals; Renal Dialysis; Silicon; Skin; Spectrophotometry, Atomic

One hundred outpatients on chronic haemodialysis with polymethylmethacrylate (PMMA) membrane dialyzer were randomly chosen. A control group of 100 likewise randomly chosen outpatients were treated with cuprophane membrane dialyzer. In both groups the treatments lasted for one year. Comparison of the test results revealed that Si, Al and beta 2-M.G levels could be reduced in patients on chronic HD with PMMA.

Topics: Aluminum; beta 2-Microglobulin; Cellulose; Female; Humans; Kidney Failure, Chronic; Male; Membranes, Artificial; Methylmethacrylates; Middle Aged; Renal Dialysis; Silicon

A 44-year-old woman was admitted to hospital with end-stage renal failure, productive cough, and decreased exercise tolerance. She had owned nine cats, which resulted in long-term exposure (18 years) to silica-containing bentonite cat litter. High-resolution computed tomography of the chest showed micronodular lesions in the lungs, and mild mediastinal lymphadenopathy. A lung biopsy revealed multinucleated giant cells, some of which had birefringent material and Schaumann bodies. X-ray photoelectron spectroscopy revealed the presence of silicon in the lung biopsy specimen, as well as in the patient's cat litter. The pulmonary condition was suggestive of sarcoid-like lung disease, rather than silicosis, sarcoidosis, or hypersensitivity pneumonitis, according to the clinicopathological findings. Renal failure appeared to be a result of chronic hypercalcemia due to extrarenal calcitriol overproduction in activated alveolar macrophages. Ultimately, the patient was diagnosed with sarcoid-like lung disease complicated by end-stage renal failure from exposure to bentonite cat litter. Therapy with steroids, in addition to elimination of the bentonite cat litter exposure, resulted in a significant improvement in the health condition. At a follow-up visit after 4 months, an almost complete resolution of the lung lesions and a significant improvement in renal function were observed.

Topics: Bentonite; Calcitriol; Female; Humans; Kidney Failure, Chronic; Lung Diseases; Sarcoidosis; Silicon; Silicon Dioxide; Skin Diseases

Chronic renal failure is exacerbated by oxidative stress, and this condition is difficult to treat in advanced stages. Because of the lack of effective treatments, the disease is a global public health concern. We developed a Si-based agent that continuously generates hydrogen for more than 24 h by reacting with water under conditions similar to those in the gastrointestinal tract. Given the efficacy of hydrogen in the treatment of conditions associated with oxidative stress, we examined whether the Si-based agent had beneficial effects on the development of renal failure. The Si-based agent was orally administered to rats that were developing renal failure. Rats underwent 5/6 nephrectomy to establish a remnant kidney model. Specifically, on day -7, rats underwent right 2/3 nephrectomy, followed by light nephrectomy on day 0. Starting on day -3, the rats were administered a control or Si-based agent-containing diet for 8 weeks. Compared with the findings in control rats, the Si-based agent greatly suppressed the increases of both serum creatinine and urinary protein levels. All analyzed parameters of oxidative stress were significantly suppressed in the Si-based agent groups. Histopathological examination illustrated that glomerular hypertrophy was suppressed by the treatment. Quantitative real-time reverse transcription-polymerase chain reaction revealed that sirtuin 1 and heme oxygenase-1 expression was increased in the Si-based agent groups, suggesting improved antioxidant activity and reduced hypoxia. In addition, caspase-3 and interleukin-6 expression was suppressed in the Si-based agent groups, indicating the alleviation of apoptosis and inflammation. In conclusion, oral administration of a Si-based agent resulted in renoprotective effects, presumably by suppressing oxidative stress via hydrogen generation.

Topics: Administration, Oral; Animals; Antioxidants; Caspase 3; Cell Hypoxia; Creatinine; Disease Models, Animal; Down-Regulation; Heme Oxygenase-1; Hydrogen; Interleukin-6; Kidney; Kidney Failure, Chronic; Male; Nephrectomy; Oxidative Stress; Rats; Rats, Sprague-Dawley; Silicon; Sirtuin 1; Up-Regulation

Hemodialysis using hollow-fiber membranes provides life-sustaining treatment for nearly 2 million patients worldwide with end stage renal disease (ESRD). However, patients on hemodialysis have worse long-term outcomes compared to kidney transplant or other chronic illnesses. Additionally, the underlying membrane technology of polymer hollow-fiber membranes has not fundamentally changed in over four decades. Therefore, we have proposed a fundamentally different approach using microelectromechanical systems (MEMS) fabrication techniques to create thin-flat sheets of silicon-based membranes for implantable or portable hemodialysis applications. The silicon nanopore membranes (SNM) have biomimetic slit-pore geometry and uniform pores size distribution that allow for exceptional permeability and selectivity. A quantitative diffusion model identified structural limits to diffusive solute transport and motivated a new microfabrication technique to create SNM with enhanced diffusive transport. We performed in vitro testing and extracorporeal testing in pigs on prototype membranes with an effective surface area of 2.52 cm2 and 2.02 cm2, respectively. The diffusive clearance was a two-fold improvement in with the new microfabrication technique and was consistent with our mathematical model. These results establish the feasibility of using SNM for hemodialysis applications with additional scale-up.

Topics: Animals; Diffusion; Humans; Kidney Failure, Chronic; Membranes, Artificial; Nanopores; Polymers; Renal Dialysis; Silicon; Solutions; Swine

Continuous ambulatory peritoneal dialysis (CAPD) is associated with various problems, including damage to the CAPD catheter. We encountered catheter rupture around the titanium adaptor in a patient who had been on CAPD for 7 years. The area near the adaptor generally suffers damage secondary to deterioration of the silicon composing the catheter. However, stereoscopic and electron microscopic observation of the surface of the catheter revealed no deterioration. Instead, there were fine scratches around the site of rupture and the broken surface was rough. Since the patient did not protect the catheter with gauze near the titanium adaptor, it was probably damaged by the adaptor and then ruptured by some external force.

Topics: Anti-Bacterial Agents; Biomechanical Phenomena; Catheters, Indwelling; Humans; Injections, Intraperitoneal; Kidney Failure, Chronic; Male; Middle Aged; Peritoneal Dialysis, Continuous Ambulatory; Peritonitis; Silicon; Titanium

Serum aluminium was significantly raised (p < 0.01) up to 2-3-fold, in patients with dementia including Alzheimers Disease (AD) 0.66 +/- 0.2 (mumol/l mean +/- 1 s.d.) and patients on regular aluminium hydroxide therapy 0.54 +/- 0.17, compared with healthy volunteers 0.21 +/- 0.13, although not as high as in patients with end stage renal failure on regular dialysis 0.88 +/- 0.42. The urine outputs (mumol/l mean +/- 1 s.d.) of aluminium and silicon, respectively, were also significantly increased up to 5-fold in dementia 2.89 +/- 1.78 (n = 23) and 1587 +/- 645 (n = 22) and patients on regular aluminium hydroxide therapy 5.03 +/- 2.08 (n = 8) and 998 +/- 364 (n = 21) compared with healthy volunteers 0.95 +/- 0.82 (n = 84) and 471 +/- 332 (n = 114). The increase in urine aluminium was thus associated with a similarly marked increase in the output of silicon. The increased absorption of aluminium in dementia patients is equivalent to the intestinal loading in Aludrox therapy. Also silicon appears to be important in the renal excretion of the absorbed aluminium. Whether this is a phenomenon related to the elderly or the process of dementia warrants further study.

Topics: Adult; Aged; Aged, 80 and over; Aging; Aluminum; Aluminum Hydroxide; Alzheimer Disease; Case-Control Studies; Dementia; Diet; Drug Combinations; Female; Humans; Intestinal Absorption; Kidney Failure, Chronic; Magnesium Hydroxide; Male; Middle Aged; Renal Dialysis; Silicon

Aluminium toxicity in dialysis patients is well described. Aluminium has a close chemical affinity with silicon. Silicon may have a role in protection against aluminium toxicity.. We measured serum aluminium and silicon levels from haemodialysis patients from four different centres.. Though no relationship was seen across all centres combined, in one centre there was a reciprocal relationship in patients on home haemodialysis (who did not require reverse osmosis). Median (range) aluminium levels were higher, 2.2 (0.4-9.6) micromol/l when serum silicon was less than 150 micromol/l, and lower, 1.1 (0.2-2.8) micromol/l when serum silicon levels were greater than 150 micromol/l (P = 0.03).. In patients treated by haemodialysis without reverse osmosis high serum silicon concentrations were associated with lower serum aluminium concentrations than those with low serum silicon. Further work needs to confirm a preventative role for silicon in the accumulation and subsequent toxicity of aluminium in dialysis patients.

Topics: Aluminum; Chronic Kidney Disease-Mineral and Bone Disorder; Hemodialysis Solutions; Hemodialysis, Home; Humans; Kidney Failure, Chronic; Osmosis; Phosphates; Renal Dialysis; Silicon; United Kingdom; Water Supply

Serum, erythrocyte and renal tissue silicon levels in normal Wister rats and in rats with chronic renal failure were examined. The relationship between serum, erythrocyte and renal tissue Si levels, and markers of renal function (BUN, serum creatinine), markers of anemia (RBC, Hb, Hct) and markers of bone formation (serum calcium, phosphate) were studied. Serum and erythrocyte Si levels were directly correlated with the markers of renal function and with serum Pi and serum Ca x P, and inversely with the markers of anemia. Renal tissue silicon levels, on the other hand, correlated only with the markers of anemia.

Topics: Anemia; Animals; Blood Urea Nitrogen; Calcium; Creatinine; Erythrocyte Count; Hematocrit; Kidney Failure, Chronic; Leukocyte Count; Male; Nephrectomy; Phosphates; Rats; Rats, Wistar; Silicon

Although silicon is considered as an essential element, little is known about the basic effects and clinical significance of increased concentrations of the element in dialysis patients.. In a multicentre study we found silicon levels in haemodialysis (HD) patients to be markedly increased. In these patients silicon concentrations were significantly higher than those noted in subjects with normal renal function as well as in patients with chronic renal failure not yet in dialysis and patients treated by continuous ambulatory peritoneal dialysis (CAPD). Moreover we noted that in both HD and CAPD patients mean silicon levels differed from one centre to another. Also, was there in the HD population a significant difference in serum silicon levels among patients from different countries. In HD patients differences in serum silicon levels were either due to the use of silicon contaminated dialysis fluids or an increased oral intake of the element mainly originating from the high silicon content of the drinking water. Silicon contamination of the dialysis fluid was found to be due to either the use of reverse osmosis membranes that insufficiently retain the element during water treatment or by the addition of concentrates containing high amounts of silicon. Using a recently developed high-performance liquid chromatographic/atomic absorption spectrophotometric (HPLC/ETAAS) hybrid technique, we found silicon in serum to be present as a low-molecular-weight non-protein-bound component, which in the presence of a low silicon dialysate is adequately removed during treatment.. The clinical relevance of increased serum silicon levels is not yet known and as such deserves further investigation. In view of the controversy that exists on the element's assumed protective as well as toxic role in the development of some (aluminium-related) neurodegenerative diseases and its vital role in bone formation, monitoring of the silicon levels in serum, tap water, and dialysis fluids might become important.

Topics: Aluminum; Chromatography, High Pressure Liquid; Humans; Kidney Failure, Chronic; Peritoneal Dialysis, Continuous Ambulatory; Reference Values; Renal Dialysis; Silicon; Spectrophotometry, Atomic; Water Pollution, Chemical; Water Purification

We examined the relationship between recombinant human erythropoietin (rHuEPO) therapy and serum levels of the trace elements aluminum, silicon, zinc, nickel, and manganese in 55 patients undergoing chronic hemodialysis (HD) in whom rHuEPO (for 12 weeks) was effective in reducing anemia, and in 55 patients undergoing HD without rHuEPO treatment. In the rHuEPO group, serum Al level was significantly decreased and Si level showed a tendency to decrease. Zn, Ni, and Mn levels, however, were significantly increased.

Topics: Adult; Aged; Aluminum; Anemia; Combined Modality Therapy; Erythropoietin; Female; Humans; Kidney Failure, Chronic; Male; Manganese; Middle Aged; Nickel; Renal Dialysis; Silicon; Trace Elements; Zinc

Serum vanadium, aluminum, silicon and beta 2-microglobulin levels as well as the red cell count, hemoglobin and systolic blood pressure were simultaneously measured in 80 chronic hemodialysis patients. The serum vanadium level was positively correlated with the serum levels of aluminum, silicon and beta 2-microglobulin as well as the systolic blood pressure, and was inversely correlated with the red cell count and hemoglobin. The mean serum vanadium level was 18.4 +/- 7.6 ng/ml before hemodialysis and decreased to 13.0 +/- 5.30 ng/ml at the completion of dialysis. The dialysate vanadium level increased from 0.4 +/- 0.2 (inflow) to 1.0 +/- 0.4 ng/ml (outflow). It was concluded that vanadium was transferred from blood to dialysate when purified water was used in the preparation of the dialysate.

Topics: Aged; Aluminum; beta 2-Microglobulin; Blood Pressure; Bone Diseases; Erythrocyte Count; Female; Hemoglobins; Humans; Iron; Kidney Failure, Chronic; Male; Middle Aged; Renal Dialysis; Silicon; Vanadium

Plasma silicon measurements have been obtained in patients with end-stage renal disease on chronic dialysis therapy. The mean +/- SE values for normal plasma silicon concentrations are .15 +/- .02 mg/L. All dialysis groups showed marked elevations in their plasma silicon that correlated with the silicon content of their respective dialysis fluids. The values of two different hemodialysis groups and a peritoneal dialysis group were 4.6 +/- .4, 2.5 +/- .2, and 1.9 +/- 1.2 mg/L, respectively. The silicon content of their respective dialysis fluids were 4.0 +/- .7, 0.5 +/- .4, and 0 +/- .1 mg/L. The ultrafiltrability of plasma silicon through Cuprophane membranes was 79 +/- 2%. Hemodialysis patients drinking high-silicon well water showed significantly higher plasma silicon levels than patients drinking lower silicon municipal water. It is concluded that use of dialysis fluid with elevated silicon levels and the consumption of water containing high concentrations of silicon are two important determinants of silicon levels in a dialysis population. We observed no overt effects of silicon accumulation on the health status of our dialysis patients.

Topics: Dialysis Solutions; Female; Humans; Kidney Failure, Chronic; Male; Middle Aged; Renal Dialysis; Silicon; Water Supply

Topics: Adult; Aluminum; Amyloid; Amyloid beta-Peptides; Brain; Humans; Inclusion Bodies; Kidney Failure, Chronic; Middle Aged; Renal Dialysis; Silicon

Elemental silicon, present as soluble silicic acid in serum and urine, has been measured by direct current plasma emission spectrometry. The method is precise and accurate, yields a standard curve that is linear up to 1000 mumol/L, and requires only a simple dilution in 10 mL/L HNO3. No spectral or background interferences have been observed from serum or urine; the absolute detection limit for silicon was 0.5 mumol/L. Silicon concentrations in serum increase by up to 20-fold in patients with chronic renal failure on hemodialysis, an increase apparently related to dietary silicon intake. No relationship with aluminum was observed in hemodialysis patients, with or without aluminum toxicity. In the undialyzed patient with chronic renal failure, the concentrations of silicon in plasma increased with decreasing glomerular filtration rate. This increase may protect renal-failure patients from possible aluminum toxicity by promoting formation of the relatively inactive aluminosilicate complex. Silicon concentrations in urine of healthy individuals exceed their serum concentrations by 20- to 100-fold. Silicon excretion in patients with renal stones was not different from that in healthy controls and showed no relationship with calcium and (or) oxalate excretion.

Topics: Aluminum; Calcium; Creatine; Deferoxamine; Diet; Dose-Response Relationship, Drug; Humans; Kidney Calculi; Kidney Failure, Chronic; Renal Dialysis; Silicon

Abnormalities of trace elements such as aluminum, silicon, zinc, manganese and nickel were found in chronic hemodialysis (HD) patients. The relationship between serum concentration of trace elements and complications such as anemia bone disease, neurological disorder and nutritional disorder in 100 chronic HD patients was examined. Serum Al and Si levels were very high in these patients, and were negatively correlated with indicators of anemia such as RBC, hemoglobin and hematocrit values. Serum Al and Si levels in the HD patients with peripheral neurological disorder (excluding encephalopathy) and with bone disease were significantly high. The levels of serum Zn, Mn and Ni were low, and were correlated with total serum protein levels. In summary, in order to prevent some complications in chronic HD patients, it is very important to regulate levels of trace elements.

Topics: Aluminum; Anemia; Deferoxamine; Female; Hematocrit; Hemoglobins; Humans; Kidney Failure, Chronic; Male; Manganese; Middle Aged; Nickel; Reference Values; Renal Dialysis; Silicon; Spectrophotometry, Atomic; Trace Elements; Zinc

The urinary excretion of silicon (Si) in humans was studied in normal subjects on a low Si diet, a normal diet, and after ingestion of silicate antacid. Measurements of 24-hour urinary excretion of Si showed that urinary Si was derived mainly from dietary intake. The serum concentration of Si was determined in normal individuals and in patients with chronic renal failure. In health, serum Si is maintained within a narrow range, but a significant hypersilicaemia occurs in uraemia. The concentration of Si was measured in the water supply, dialysate and pre-dialysis and post-dialysis serum in patients on regular haemo-dialysis in three areas with low, intermediate and high concentrations of Si in the water supply. Si was removed during dialysis in the region where it was naturally low in the water or where reverse osmosis was used, but it was dialysed into patients in regions with intermediate and high concentrations in the water. Serum Si levels returned to normal after renal transplantation. Preliminary analysis of the geographical variation in the Si content of tap water suggests that uraemic hypersilicaemia may protect haemodialysed patients from the development of aluminium dementia. The kidney would appear from these studies to be the major organ for elimination of absorbed Si.

Topics: Adult; Diet; Humans; Intestinal Absorption; Kidney Failure, Chronic; Reference Values; Renal Dialysis; Selenium; Silicon; Uremia

In 36 patients suffering from chronic renal failure (mean creatinine clearance 26 ml/min), serum silicon levels were significantly increased (mean 0.52 microgram/ml compared with 0.265 microgram/ml in normals; p less than 0.005). Urinary silicon excretion per 24 h was significantly decreased (15.71 mg/24 h compared with 21.4 mg/24 h in normals; p less than 0.001). Fractional excretion of silicon (FESi) was significantly increased in chronic renal failure (p less than 0.001), with overall tubular secretion of silicon in 33% of patients. Urinary excretion of silicon was significantly related to urinary calcium excretion (p less than 0.0001) urinary magnesium excretion (p less than 0.0001) creatinine clearance (p less than 0.05) and sodium excretion (p less than 0.05). It is suggested that urinary silicon is in the form of orthosilicate, principally bound to calcium and magnesium; and that in chronic renal failure the increase in FESi, and the decrease in absorbed Si from the gastrointestinal tract, moderate the increase in plasma silicon levels and prevent excessive entry of silicon into the tissues.

Topics: Adult; Aged; Glomerular Filtration Rate; Humans; Kidney; Kidney Failure, Chronic; Male; Middle Aged; Reference Values; Silicon

Silicon levels in plasma and urine have been studied in normal subjects, in chronic renal failure patients, and in regular hemodialysis patients. Plasma levels were elevated in chronic renal failure, and in hemodialysis patients they were three times the control values. Urine silicon excretion is significantly related to creatinine clearance, and to urinary omolality, magnesium and calcium levels. A small amount of residual silicon is found in the hollow fiber artificial kidneys made by some manufacturers. High concentrations of silicon are found in commercial dialysate and pass down a chemical concentration gradient into the blood compartment. It is concluded that silicon is sequestered rapidly in the body during hemodialysis, and that this amounts to 58 g of silicic acid per annum from hemodialysis alone.

Topics: Humans; Kidney Failure, Chronic; Renal Dialysis; Silicon

Topics: Acute Kidney Injury; Blood Vessels; Fluorocarbon Polymers; Humans; Kidney Failure, Chronic; Renal Dialysis; Silicon