Disturbances of trace element concentrations in plasma of patients with chronic renal failure

Serum Zinc Levels in Chronic Kidney Disease Patients, Hemodialysis Patients, and Healthy Controls: Systematic Review and Meta-Analysis

OBJECTIVES

Patients with chronic kidney disease (CKD) are susceptible to changes in zinc homeostasis through anorexia and dietary restrictions, as well as hemodialysis (HD). Changes in zinc homeostasis might predispose CKD and HD patients to specific adverse effects, including erythropoietin-resistant anemia, oxidative stress, atherosclerosis, and cardiovascular disease. Because serum zinc levels are rarely measured in CKD and HD patients, zinc supplementations do not represent a routine therapy for CKD and dialysis patients. Therefore, in this meta-analysis, we aimed to assess serum zinc levels in CKD and HD patients compared with healthy controls (HC). In addition, we investigated whether HD affects serum zinc levels by comparing serum zinc levels in HD versus CKD patients and comparing serum zinc pre- versus post-HD.

DESIGN AND METHODS

A comprehensive search of databases was conducted to identify either observational studies or randomized trials that assessed serum zinc levels in either CKD and/or HD patients in comparison to HC. We conducted a random-effects meta-analysis.

RESULTS

Our meta-analysis included 42 studies with a total of 4,161 participants, of whom 460 were CKD patients, 2,047 were HD patients, and 1,654 were HCs. Both CKD and HD patients showed lower serum zinc levels compared with HC (mean difference = -22.86 μg/dL, 95% CI -33.25 to -12.46; mean difference = -13.64 μg/dL, 95% CI -21.47 to -53.80, respectively). CKD and HD patients showed no significant difference in serum zinc levels (mean difference = 15.39, 95% CI -8.91 to 39.68). Pre-HD serum zinc levels were significantly lower than those post-HD (mean difference = -7.51 μg/dL, 95% CI -14.24 to -0.78).

CONCLUSION

In the current study, the serum zinc levels were lower in CKD and HD patients compared to HCs and appears to be more common than reported in daily clinical practice. It may be beneficial to assess serum zinc levels in CKD and HD patients. More research on zinc in kidney disease is encouraged.

A Formula for Correcting Plasma Zinc Levels against Protein Concentration

Plasma zinc and total protein concentrations were measured in 13 normal volunteers, before and after a five-minute occlusion of the antecubital vein with a sphygmomanometer cuff. The percentage increment before and after five minutes of venous occlusion was 10.2 ± 4.7% for total protein and 8.8 ± 6.0% for zinc concentration. Both these differences were statistically significant (p < 0.001). We propose an equation for correction of plasma zinc levels according to concentration of total proteins. Using this equation the corrected values of plasma zinc before and after 5 minutes of venous occlusion were similar, that is, 12.33 ± 1.94 and 12.20 ± 2.05 μmol/l. In addition we found that of seven hypoproteinemic patients on continuous ambulatory peritoneal dialysis (CAPD) who had low plasma zinc levels compared to normal (uncorrected for protein concentration) controls, only two had “true” hypozincemia when their plasma zinc was corrected against protein using this formula and compared to normals (corrected for protein) controls. The paper discusses the clinical usefulness of this adjustment of measurements of plasma zinc concentration.

Renal Osteodystrophy and the Status of Aluminum and Other Trace Metals in CAPD Patients: A Panel Review

Most reports indicate that in patients on CAPD, hyperparathyroid bone disease progresses, while osteomalacia improves. With 1.5g% Dianeal, and when dialysate Ca is 7mg%, peritoneal mass transfer of calcium is positive, i.e., it is absorbed from the solution, while with hypertonic solutions it is less positive or even negative. Daily phosphorus removal by CAPD is insufficient to control serum phosphorus, hence CAPD patients require phosphate binders and/or phosphate restriction. Peritoneal phosphorus removal is greater with hypertonic than with isotonic solutions.

In patients on CAPD, the loss of substantial amounts of D-binding protein and 25(OH)DJ into the dialysate, produces a gradual decrease in plasma 25(OH)D levels. Similarly, these patients have low 1,25(OH)D2 DJ levels and, hence, should receive vitamin D or its analogues.

Unlike hemodialysis, CAPD results in a significant removal of PTH, with a peritoneal clearance of 1.5 ml/min. However, despite an estimated daily loss of 13.5% of the circulating PTH, there probably is not a significant effect on plasma PTH levels, which usually respond to changes in serum Ca. Levels of the intact PTH molecule provide a better index of hyperparathyroidism than do levels of its COOH-terminal fragment.

With regard to investigation and treatment, one should measure serum ionic calcium rather than total calcium, even if the latter is corrected for total protein. The minimal dialysate calcium should be 7 mg/dl and for hypertonic solutions, perhaps it should be higher (7.5–8.0 mg%). Total serum calcium should be maintained at 10.2–10.7 mg/dl (ionized calcium of 5.1–5.5 mg/dl); adjunctive use of active forms of vitamin D and prevention of aluminum intoxication may prevent progressive bone disease in CAPD, and existing bone disease may heal.

Whereas there are enough data supporting the connection of aluminum toxicity and osteomalacia in hemodialysis patients, data concerning the incidence of osteomalacia and its relationship to aluminum in CAPD patients are scarce. Apparently CAPD removes aluminum more efficiently than hemodialysis. CAPD patients are less likely to develop osteomalacia because the dialysate aluminum content is low and these patients tend to require lower doses of phosphate binder.

There are no extensive studies on trace element deficiencies or excess in patients on CAPD. These patients may be more susceptible to deficiencies of trace elements which are protein bound. Desferoxamine may be effectively used for the treatment of patients with either aluminum or iron overload.

Serum Ferroxidase I and II in Uremic Patients under Conservative Treatment and Maintenance Hemodialysis

Serum ferroxidase I (ceruloplasmin) and ferroxidase II activities were studied in 49 uremic patients under conservative treatment, in 79 patients undergoing hemodialysis and in 56 healthy subjects, as controls. Ferroxidase I was significantly higher in both groups of patients. Ferroxidase II was significantly elevated only in patients undergoing chronic hemodialysis. The cause of this difference is not clear, but seems to be of considerable interest.

Metabolic and Nutritional Aspects of Acute Renal Failure in Critically Ill Patients Requiring Continuous Renal Replacement Therapy

Acute renal failure (ARF) is rarely an isolated process but is often a complication of underlying conditions such as sepsis, trauma, and multiple-organ failure in critically ill patients. As such, concomitant clinical conditions significantly affect patient outcome. Poor nutritional status is a major factor in increasing patients' morbidity and mortality. Malnutrition in ARF patients is caused by hypercatabolism and hypermetabolism that parallel the severity of illness. When dialytic intervention is indicated, continuous renal replacement therapy (CRRT) is a commonly used alternative to intermittent hemodialysis because it is well tolerated by hemodynamically unstable patients. This paper reviews the metabolic and nutritional alterations associated with ARF and provides recommendations regarding the nutritional, fluid, electrolyte, micronutrient, and acid-base management of these patients. The basic principles of CRRT are addressed, along with their nutritional implications in critically ill patients. A patient case is presented to illustrate the clinical application of topics covered within the paper.

Trace elements in hemodialysis patients: a systematic review and meta-analysis

BACKGROUND

Hemodialysis patients are at risk for deficiency of essential trace elements and excess of toxic trace elements, both of which can affect health. We conducted a systematic review to summarize existing literature on trace element status in hemodialysis patients.

METHODS

All studies which reported relevant data for chronic hemodialysis patients and a healthy control population were eligible, regardless of language or publication status. We included studies which measured at least one of the following elements in whole blood, serum, or plasma: antimony, arsenic, boron, cadmium, chromium, cobalt, copper, fluorine, iodine, lead, manganese, mercury, molybdenum, nickel, selenium, tellurium, thallium, vanadium, and zinc. We calculated differences between hemodialysis patients and controls using the differences in mean trace element level, divided by the pooled standard deviation.

RESULTS

We identified 128 eligible studies. Available data suggested that levels of cadmium, chromium, copper, lead, and vanadium were higher and that levels of selenium, zinc and manganese were lower in hemodialysis patients, compared with controls. Pooled standard mean differences exceeded 0.8 standard deviation units (a large difference) higher than controls for cadmium, chromium, vanadium, and lower than controls for selenium, zinc, and manganese. No studies reported data on antimony, iodine, tellurium, and thallium concentrations.

CONCLUSION

Average blood levels of biologically important trace elements were substantially different in hemodialysis patients, compared with healthy controls. Since both deficiency and excess of trace elements are potentially harmful yet amenable to therapy, the hypothesis that trace element status influences the risk of adverse clinical outcomes is worthy of investigation.

Zinc supplementation at conventional doses does not improve the disturbance of taste perception in hemodialysis patients

OBJECTIVE

To determine the effect of zinc supplementation on taste perception in a group of hemodialysis patients.

DESIGN AND SETTING

Double-blind randomized placebo-controlled study in a teaching hospital dialysis unit.

PATIENTS

Fifteen stable hemodialysis patients randomized to placebo (6 male, 2 female; median age, 67; range, 30 to 72 years) or treatment (5 male, 2 female; median age, 60; range, 31 to 76 years).

INTERVENTION

Treatment group received zinc sulfate 220 mg per day for 6 weeks, and the placebo group received an apparently identical dummy pill.

MAIN OUTCOME MEASURES

Taste scores by visual analogue scales, normalized protein catabolic rate and plasma, whole blood and red cell zinc levels.

RESULTS

At baseline, sweet and salt tastes were identified correctly by both groups. Sour was often confused with salt. Sour solutions of different concentrations were not distinguishable. Taste scores were not different after 6 weeks for either group. There was no significant increment in zinc levels or normalized protein catabolic rate for either group.

CONCLUSION

We found a disturbance of taste perception in hemodialysis patients, particularly for the sour modality, which was not corrected by this regimen of zinc supplementation. These results cast doubts on the conclusions of earlier studies that indicated an improvement in taste after zinc supplementation.

An evaluation of the influence of therapeutic interventions on serum trace element levels in groups of patients

The aim of the study was to propose a method of large amount data evaluation. A new graphical method for data evaluation was suggested: the data were ranked according to the initial values and both the initial values and final values were intersected by polynomial curves. This method was used in the following situations: 1. Serum levels of Mg and Zn were measured just before and after hemodialysis (HD) in 87 patients in chronic renal failure. 2. Mg levels in serum, red blood cells and urine were estimated in 20 patients before and after administration of a Mg containing drug. Three basic graphic forms of curves were established: 1. Significant decrease of serum Mg levels during HD resulted in two uncrossed lines, the initial-values line being higher than terminal-values one (the higher the initial level the more pronounced was its decrease during HD). 2. Balanced effect of HD on the serum levels of Zn (low values increased, high levels decreased) represented two crossing-lines. 3. Significant increase of urine Mg in patients supplemented by Mg demonstrated two uncrossed lines. The position of initial-values curve was lower than the terminal-values one. The proposed graphical method of the evaluation of large amounts of data is simple and enables a quick orientation in the assessment of the effects of therapeutic interventions (trace elements, drugs and other relevant substances).

Hemodialyzability of ionizable fluoride in hemodialysis session

The fluoride ion content in serum and in dialysate medium was determined by means of a fluoride ion-selective electrode in 29 patients undergoing hemodialysis treatment. Abnormally high serum fluoride of 65.9 +/- 28.3 microg l(-1) at the beginning and 46.5 +/- 26.7 microg l(-1) at the completion of the hemodialysis session was observed. Results showed that 60.0 +/- 23.9% of the serum fluoride at the beginning of the session was theoretically filterable, and 80.8 +/- 42.4% of this fraction was actually filtered throughout the hemodialysis session. The dialysis procedure is considered to be safe and adequate for serum fluoride removal. The high serum fluoride at the completion of the hemodialysis session was thought to originate from the fraction of unfilterable binding fluoride. To make further progress towards improvements in serum fluoride removal during HD, attention to the binding fraction of serum fluoride is required.

Selenium and glutathione levels, and glutathione peroxidase activities in blood components of uremic patients on hemodialysis supplemented with selenium and treated with erythropoietin

Patients with chronic renal failure (CRF) often have reduced concentrations of selenium (Se) and lowered activities of glutathione peroxidase (GSH-Px) in blood components. The kidney is a major source of plasma GSH-Px. We measured Se and glutathione levels in blood components and red cell and plasma GSH-Px activities in 58 uremic patients on regular (3 times a week) hemodialysis (HD). The dialyzed patients were divided in 4 subgroups and were supplemented for 3 months with: 1) placebo (bakers yeast), 2) erythropoietin (EPO; 3 times a week with 2,000 U after each HD session), 3) Se-rich yeast (300 microg 3 times a week after each HD), and 4) Se-rich yeast plus EPO in doses as above. The results were compared with those for 25 healthy subjects. The Se concentrations and GSH-Px activities in the blood components of dialyzed uremic patients were significantly lower compared with the control group. Treatment of the HD patients with placebo and EPO only did not change the parameters studied. The treatment with Se as well as with Se and EPO caused an increase in Se levels and red cell GSH-Px activity. Plasma GSH-Px activity, however, increased only slowly or did not change after treatment with Se and with Se plus EPO. In the group treated with Se plus EPO the element concentration in blood components was higher compared with the group supplemented with Se alone. The weak or absence of response in plasma GSH-Px activity to Se supply indicates that the impaired kidney of uremic HD patients has reduced possibilities to synthesize this enzyme.

Serum and tissue selenium contents related to renal disease and colon cancer as determined by electrothermal atomic absorption spectrometry

Microwave digestion with nitric acid and hydrogen peroxide was applied to the determination of selenium in biological tissues by Electrothermal Atomic Absorption Spectrometry (ETAAS). Validation of this method is presented in terms of adequate recovery of selenium from standard reference materials and the method is applied to carcinogen human colon tissue. Ultramicrofiltration was used to study selenium protein binding and its fractionation and speciation in blood serum. These studies showed that 95% of the total selenium in serum seems to be bonded to high-molecular-weight proteins. Experiments with renal failure patients showed lower selenium levels than in the health population (0.57 +/- 0.23 mM versus 0.81 +/- 0.11 mM). A wider distribution pattern of total serum selenium concentration (from 0.1 to 1 mM) was clearly observed in renal failure patients. However, the ultramicrofiltrable selenium fraction was always constant, even in the presence of desferrioxamine (DFO).

Hemodialysis effect on serum boron level in the patients with long term hemodialysis

Serum and dialysate boron levels in 17 patients with long term hemodialysis (HD) were determined by inductively coupled plasma emission spectrometry (ICPES). Serum boron level was compared with the value of age matched 467 healthy controls and the relationship between serum and dialysate boron level was analyzed. The results showed that serum boron level was significantly higher at the beginning of HD, and lower at the completion of HD in comparison with controls. Although the dialysate was contaminated with trace boron, HD resulted in an excessive decrease of serum boron, rather than boron exposure from the dialysate. Boron hemodialyzability was almost proportional to the gradient of the boron level at the beginning of HD and it could be controlled by the adjustment of the gradient. In conclusion, the serum boron level was very much disturbed in long term HD patients. If boron excess in serum at the beginning of HD, or deficiency at the completion of HD may contribute to the complications of HD patients, fine adjustment and close surveillance of the gradient should be taken into account.

Selenium in uremia

The importance of selenium as an essential trace element for man has been increasingly recognized during the last several years. Selenium deficiency has been associated with cases of congestive cardiomyopathy, skeletal myopathy, anemia, enhanced cancer risk, elevated incidence of cardiovascular disease, immune system alterations, hair and nail changes, and abnormalities in thyroid hormone metabolism. These symptoms are frequently present in chronic uremic patients. Nevertheless, the prevalence and significance of selenium deficiency in the uremic syndrome is still not clearly defined. This article reviews the selenium status in chronic uremic patients, the supposed pathogenetic mechanisms of selenium disturbance in uremia, and the possible role of selenium deficiency on some uremic abnormalities.

Hemodialysis with regenerated cellulosic membranes does not reduce plasma selenium levels in chronic uremic patients

Selenium (Se) is considered an essential and very important trace element for humans. Se blood levels are frequently low in end-stage renal disease (ESRD) patients, but very little has been established concerning the mechanisms that could modify Se status in uremia, including a supposed dialysis-mediated Se depletion. In order to verify whether hemodialysis (HD) can induce a loss of Se, thereby leading or contributing to a low plasma Se concentration, we investigated the effect of HD procedure with the most commonly used regenerated cellulosic membrane (Cuprophan) on plasma Se levels in 20 uremic patients on HD for 62.5 +/- 49.4 months. Plasma Se levels were also determined in 15 chronic renal failure (CRF) nondialyzed patients and in 28 age-matched healthy controls. Se concentration was determined by atomic absorption spectrophotometry. Plasma Se levels of both HD patients (61.3 +/- 8.5 micrograms/L) and CRF nondialyzed patients (56.4 +/- 10.1 micrograms/L) were significantly lower than in normal subjects (78.3 +/- 9.7 micrograms/L, p < 0.001). In CRF nondialyzed patients, a significant (p < 0.05) negative correlation was found between the plasma Se concentration versus serum creatinine values. Within the HD group, plasma Se levels significantly increased after the HD procedure (72.8 +/- 17.2 micrograms/L, p < 0.02) together with hematocrit and total plasma protein values (p < 0.05 and p < 0.001, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Essential trace elements in humans. Serum arsenic concentrations in hemodialysis patients in comparison to healthy controls

Serum arsenic concentrations of persons suffering from renal failure and undergoing hemodialysis treatment (n = 85) and of healthy controls (n = 25) were determined by hydride-generation AAS technique after microwave digestion. The results were evaluated by comparing the values of both groups, considering physiological factors and individual data, as well as comorbid conditions of the hemodialysis (HD) patients. Serum arsenic levels were diminished in the patient group compared with controls (mean values 8.5 +/- 1.8 ng/mL vs 10.6 +/- 1.3 ng/mL). Furthermore, additional diseases within the hemodialysis group, particularly injuries of the central nervous system (CNS), vascular diseases, and cancer, were correlated to occasionally markedly decreased serum arsenic concentrations. It was concluded that arsenic homeostasis is disturbed by HD treatment and certain additional diseases. Desirable arsenic concentrations in the body seem to be reasonable. This consideration results in the conclusion that arsenic could play an essential role in human health. Thus, reference arsenic concentrations in different human tissues and body fluids should be established in order to recognize not only arsenic intoxication, but also arsenic deficiency. Perhaps arsenic deficiency contributes to the increased death risk of HD patients, and therefore, arsenic supplementations for patients with extremely low serum arsenic concentrations should be taken into account.

Serum selenium and glutathione-peroxidase activities and their interaction with toxic metals in dialysis and renal transplantation patients

Selenium, aluminum, cadmium, and magnesium concentrations and glutathione-peroxidase activities in sera of 35 healthy individuals, 30 renal transplants, and 30 hemodialysis patients were measured. Serum selenium, aluminum, and cadmium concentrations in both groups of patients were higher than the controls (p less than 0.001), whereas the serum glutathione-peroxidase levels were lower (p less than 0.001). According to our results, it can be concluded that the patients receiving hemodialysis are subjected to more toxic elements than the transplantation patients. These findings imply that dietary selenium supplement may be suggested in renal failure for the detoxification of elements, such as cadmium and mercury. The essential trace element selenium takes part not only in the direct protection of endothelial cells against the accumulation of aggressive oxygen species, but also in the prevention of the toxic effects of cadmium or in the modulation of the active calcium transport.

A sequential and simple determination of zinc, copper and aluminium in blood samples by inductively coupled plasma atomic emission spectrometry

A sequential method of measuring zinc, copper and aluminium in serum by inductively coupled plasma (ICP) spectrometry is described. It involves a 1/5 dilution of serum with a potassium chloride solution which enhances aluminium signal intensity and reduces variations between different matrix compositions. The method is as sensitive as atomic absorption for zinc (sensitivity: 0.11 mumol/l) and copper (sensitivity: 0.020 mumol/l) and can also be applied to monitor aluminium (sensitivity: 0.12 mumol/l) for patients receiving total nutrition therapy or hemodialysis. Its linearity extends at least to 200 mumol/l for copper and zinc and to 20 mumol/l for aluminium. The correlations with atomic absorption are satisfactory for the 3 parameters, as assessed by the correlation coefficients established for both methods. A reference interval was established with 34 sera of control subjects (19 men, 15 women) which showed an average zinc, copper and aluminium of 14.5 (S.D. 2.6), 17.3 (S.D. 2.1) and 0.32 (S.D. 0.12) mumol/l, respectively. This method does not require a simultaneous ICP spectrometer and can be performed with 1 ml of serum in a single tube, using a routine sequential ICP spectrometer.

Impaired function of macrophage Fc gamma receptors in end-stage renal disease

Infection is a frequent complication in patients undergoing hemodialysis for end-stage renal disease and is the primary cause of mortality among such patients. Macrophages are important in host defense against infection largely because their Fc gamma receptors recognize antibody-coated bacteria. We therefore studied macrophage Fc gamma-receptor function in vivo and in vitro in 56 patients with end-stage renal disease who were on hemodialysis and in 20 healthy volunteers. The clearance of IgG-coated (sensitized) autologous red cells was decreased in 53 patients. The inhibition of clearance in the 56 patients was 52 +/- 3 percent at 1 hour, 41 +/- 5 percent at 1 1/2 hours, and 29 +/- 5 percent at 2 hours (P less than 0.001). The clearance of unsensitized erythrocytes and heat-altered autologous erythrocytes was normal. The impairment of clearance was not correlated with age, sex, nutritional status, HLA haplotype, or the presence of circulating immune complexes. The recognition of these IgG-sensitized red cells in vitro by Fc gamma RI (an Fc gamma-receptor protein that binds monomeric IgG) on blood monocytes from the patients was also significantly decreased (P less than 0.001) but was partially improved by hemodialysis. Nine patients had severe infections during a two-year follow-up period. The clearance of IgG-coated cells in these patients (half-time, 12.9 +/- 1.7 hours) was significantly impaired, as compared with that in the 47 patients without severe infections (half-time, 4.4 +/- 1.8 hours; P less than 0.001). We conclude that macrophage Fc gamma-receptor function is impaired in patients with end-stage renal disease who are undergoing hemodialysis, and that this impairment probably contributes to the observed immunodepression and high prevalence of infection among such patients.

Zinc in kidney disease

Abnormalities of Zn metabolism are well documented in patients with chronic renal disease, especially those with nephrotic disease and uremia. The causes of Zn deficiency in kidney disease are not clear. Decreased dietary Zn intake and intestinal absorption, increased endogenous Zn secretion, and increased urinary Zn excretion (as in the nephrotic syndrome and in renal transplant recipients) all may contribute to altered Zn metabolism. Zn depletion may account for decreased taste, sexual and gonadal dysfunction, hyperprolactinemia, glucose intolerance, hyperlipidemia, growth retardation in children, neuropathy, anemia, abnormalities of neutrophil and lymphocyte function, and delayed wound healing. The benefit of pharmacologic doses of Zn, in the treatment of such manifestations, requires further evaluation under controlled conditions. Before use of Zn routinely for therapeutic purposes in uremic subjects, the cause(s) of abnormal Zn metabolism should be identified.

Selenium: clinical significance and analytical concepts

Selenium is an essential trace element in humans and animals. Its only established function in humans is the antioxidant activity of glutathione peroxidase, a selenoenzyme. Severe prolonged deficiency may cause a fatal cardiomyopathy. Iatrogenic causes of selenium deficiency include parenteral and enteral nutrition. Low plasma selenium is also found in malabsorption, cystic fibrosis, rheumatoid arthritis, neoplasia, and other varied clinical disorders. Death has resulted from a single massive ingestion of selenium, while chronic excessive intake causes skin, nail, and hair pathology. Extreme geographical variation in population blood and urine selenium levels and a marked age-specific variation in population reference intervals are important factors in understanding selenium nutrition. Nutritional requirements, biological availability, and metabolism are discussed in relation to geographical, age, and method variability. Sampling, processing procedures, and methods for selenium quantitation are reviewed. Selenium content in different biological matrices and reference values for pediatric, adult, and obstetric populations are provided.

Trace elements in serum, packed cells, and dialysate of CAPD patients

Neutron Activation Analysis (NAA) was used to investigate trace element patterns in serum, packed cells, and dialysate of CAPD patients. The concentrations of the elements Cs, Cu, Fe, and Mn in serum and packed cells appeared to be maintained within the normal range, while the levels of the non-essential element Br in both serum and packed cells were subnormal. The serum Cr values were extremely high (20 to 50 times higher than the normal serum level). The amount of Cr absorbed from the dialysate was calculated to be ten times higher than the daily dietary uptake. The Co concentrations were normal in packed cells but were significantly increased in serum. The Rb content in packed cells was slightly lower than normal, while the serum value was normal. Se was maintained within the normal range in packed cells, but the serum concentration was slightly lower than normal. The concentrations of Zn were low in serum and appeared to be higher than normal in packed cells. In conclusion, this analysis of the trace element status of CAPD patients reveals two major abnormalities. There is an apparent loss of Br from the blood towards the dialysate and on the other hand, a dramatic accumulation of Cr into the blood as a result of the very high Cr content in the dialysate.

Aluminum-associated bone disease in chronic renal failure: high prevalence in a long-term dialysis population

Twenty-seven asymptomatic patients treated with hemodialysis longer than 8 years (mean 12.9 +/- 3.1 years) underwent bone biopsy to determine the prevalence of aluminum-associated bone disease. None had excess aluminum exposure from the dialysate. Ten patients (37%) had aluminum-associated bone disease as defined by a bone formation rate (BFR) below normal in the presence of stainable bone aluminum that covered more than 25% of the trabecular surface. The predominant type of bone histology in this group was the aplastic lesion characterized by low bone turnover, a decreased number of osteoblasts, and lack of excess unmineralized osteoid. Osteoblastic osteoid was highly correlated with stainable surface bone aluminum (r = -.82, p less than .001). Among the dynamic bone parameters, the double-tetracycline labeled surface was a more sensitive indicator of impaired bone function than was the bone apposition rate (BAR), since half of the patients with aluminum-associated bone disease had a normal BAR. In all of the biopsies the extent of double-labeled surfaces was inversely proportional to the amount of stainable aluminum on the bone surface (r = -.71, p less than .001), whereas stainable bone aluminum did not correlate with BAR. In seven of the patients with aluminum-associated bone disease, amino-terminal PTH levels were in the normal range while only one patient had a normal plasma mid-region PTH. PTH correlated directly with osteoblastic osteoid, BFR, and double-labeled surfaces. These results indicate that long-term oral aluminum intake in hemodialysis patients results in a high prevalence of aluminum-associated bone disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of haemodialysis and renal transplantation on trace element concentrations in children with chronic renal failure

Whole blood levels of Cd and Pb (microgram/g Hb), serum concentrations of Sr and Zn and their urinary excretion were measured in healthy, renal transplant and dialyzed children by atomic absorption spectroscopy. Furthermore, before and after dialysis the concentrations of these elements were determined in blood/serum as well as in the dialysis fluid. The predialytic concentrations of Cd, Pb and Sr in blood/serum were significantly increased compared to controls. Haemodialysis had only minor effects on whole blood Cd and Pb levels but serum Sr and Zn concentrations increased as a result of high metal levels in dialysis fluid. Children after renal transplantation showed no alterations in Pb, Sr and Zn concentrations compared to healthy children but whole blood Cd was increased. According to the renal function the Pb, Cd and Zn urinary excretion decreased in the following order: healthy, renal transplant and dialysis children. Sr urinary excretion was increased in haemodialysis and renal transplant patients. In conclusion, we found no Zn deficiency. Elevated blood levels of Cd and Pb and elevated Sr serum concentrations in paediatric patients undergoing dialysis and increased Cd whole blood levels in renal transplant children could be of clinical interest.

Aluminium toxicity in chronic renal insufficiency

Aluminium is a ubiquitous element in the environment and has been demonstrated to be toxic, especially in individuals with impaired renal function. Not much is known about the biochemistry of aluminium and the mechanisms of its toxic effects. Most of the interest in aluminium has been in the clinical setting of the haemodialysis unit. Here aluminium toxicity occurs due to contamination of dialysis solutions, and treatment of the patients with aluminium-containing phosphate binding gels. Aluminium has been shown to be the major contributor to the dialysis encephalopathy syndrome and an osteomalacic component of dialysis osteodystrophy. Other clinical disturbances associated with aluminium toxicity are a microcytic anaemia and metastatic extraskeletal calcification. Aluminium overload can be treated effectively by chelation therapy with desferrioxamine and haemodialysis. Aluminium is readily transferred from the dialysate to the patient's bloodstream during haemodialysis. Once transferred, the aluminium is tightly bound to non-dialysable plasma constituents. Very low concentrations of dialysate aluminium in the range of 10-15 micrograms/l are recommended to guard against toxic effects. Very few studies have been directed towards the separation of the various plasma species which bind aluminium. Gel filtration chromatography has been used to identify five major fractions, one of which is of low molecular weight and the others appear to be protein-aluminium complexes. Recommendations on aluminium monitoring have been published and provide 'safe' and toxic concentrations. Also, the frequency of monitoring has been addressed. Major problems exist with the analytical methods for measuring aluminium which result from inaccurate techniques and contamination difficulties. The most widely used analytical technique is electrothermal atomic absorption spectrometry which can provide reliable measurements in the hands of a careful analyst.

Trace elements in human body fluids and tissues

Published figures for trace element concentrations in body fluids and tissues of apparently healthy subjects are widely divergent. For a considerable time, the apparent disparities were readily ascribed to biological sources of variation such as age, sex, dietary habits, physiological conditions, environmental exposure, geographical circumstances, or similar influences. Growing evidence, however, suggests that this interpretation may be seriously questioned in numerous instances. First, values obtained in reference materials leave no doubt that some previous studies must have been subject to gross analytical inaccuracies. Second, it has now been thoroughly documented that inadequate sample collection and manipulation may drastically distort the intrinsic trace element content of biological matrices. This review scrutinizes data reported by a number of investigators. In an effort to settle the currently flourishing confusion, critically selected reference values are set forth for trace element levels in human blood plasma or serum, packed blood cells, urine, lung, liver, kidney, and skeletal muscle tissue.

Quantitative study of aluminum binding to human serum albumin and transferrin by a chelex competitive binding assay

Binding of aluminum to human serum albumin and transferrin was investigated using a competitive binding assay incorporating a cation exchange resin, chelex. Both albumin and transferrin were found to produce linear Scatchard plots of aluminum binding data over the aluminum and protein concentration ranges found in humans. Binding constants measured for albumin and transferrin were 1.96 and 0.515 microM, respectively.

Zinc in patients with chronic renal failure

In order to assess zinc status in patients with chronic renal failure (CRF) plasma and erythrocyte zinc levels were determined in 13 patients undergoing regular haemodialysis. Additional determinations of plasma copper, plasma and erythrocyte magnesium and potassium were also performed. The mean plasma zinc level was slightly less than normal, but the difference was not statistically significant. The erythrocyte zinc content, however, as well as erythrocyte magnesium and potassium levels were significantly increased (p less than 0.001). This increase may be partly related to haemolysis in uraemia. Plasma copper concentration in CRF patients did not differ significantly from the control level. The almost normal plasma zinc concentration, elevated erythrocyte zinc, and normocupraemia do not indicate zinc deficiency in CRF patients.

Study of trace elements in patients on haemodialysis

The serum aluminium, zinc, copper, iron and cadmium levels were studied in patients on haemodialysis, by the atomic absorption method and spectrophotometry. The serum concentrations of zinc and copper were found to decrease with the frequency of dialysis treatments, while the serum levels of iron and aluminium increased. Referred to the time elapsed since the start of the dialysis programme, the serum concentrations of zinc decreased, while those of iron, copper and aluminium increased. Attention is drawn to published observations pointing to the hazard of aluminium intoxication and to the symptoms and consequences of copper and zinc deficiency.

Aluminum associated bone disease: clinico-pathologic correlation

A chemical, aurine tricarboxylic acid was used to identify aluminum in bone in a group of chronic renal failure patients with severe osteomalacia. Thirteen out of 49 (26%) patients had a positive stain at the bone-osteoid junction. The presence of aluminum at the staining site was confirmed by electron dispersion x-ray analysis. The patients' biopsies staining negative with this clinical, although having high bone aluminum levels, had more significant features of hyperparathyroidism, both biochemically and histologically than those having a positive stain. The usefulness of this technique to diagnose presymptomatic aluminum related osteomalacia is emphasized.