Trace minerals in patients with end-stage renal disease

The Abundance of Trace Elements in Human Bone Relative to Bone Type and Bone Pathology

As the global population ages and the proportion of individuals afflicted with musculoskeletal disease spirals upward, there is an increasing interest in understanding and preventing bone-related diseases. Bone diseases, such as osteoporosis and osteoarthritis, are known to be influenced by a variety of factors including age, gender, nutrition, and genetics, but are also inherently linked to the human body's ability to produce biominerals of suitable quality. Because the crystal lattice structure and mineralogy of bone hydroxyapatite is surprisingly analogous to geological hydroxyapatite, trace element levels and exposure have long been proposed to influence the structure of biominerals as they do geological minerals (e.g., strontium substitution changes the crystal lattice of bone minerals, while toxic lead disrupt bone cellular processes leading to bone disease). Here, we explore the distribution of trace elements in human bones to evaluate the distribution of these elements with respect to bone type (cortical vs. trabecular) and bone disease (osteoarthritis vs. osteoporosis). We find higher concentrations of many metabolically active transition metals, as well as lead, in cortical bone compared to trabecular bone. When compared to patients who have osteoarthritis, and thus presumably normal bone minerals, osteoporosis patients have higher concentrations of scandium and chromium (Cr) in trabecular bone, and Cr and lead in cortical bone. Lower concentrations of barium and titanium are associated with osteoporotic trabecular bone. This survey is an exploratory cross-sectional geochemical examination of several trace element concentrations previously understudied in human bone minerals.

Serum Chromium Levels Are Higher in Peritoneal Dialysis than in Hemodialysis Patients

Background:An elevation in serum chromium levels in individuals treated with renal replacement therapy has been previously described, but chromium levels have not been systematically studied in patients treated with different dialysis modalities. The aim of this study was to compare serum chromium levels in patients treated with chronic peritoneal dialysis (PD) and hemodialysis (HD).Methods:We studied 169 chronic dialysis patients in a single medical center, of which 148 were treated with HD and 21 with PD. Serum chromium levels were measured by atomic absorption spectrometry.Residual renal function was accessed using a timed urine collection for the measurement of urine output and calculation of glomerular filtration rate (GFR).Results:The median (interquartile range) serum chromium level was significantly higher in patients treated with PD than in patients treated with HD: 5.00 (3.24 - 6.15) vs 1.83 (1.29 - 2.45) mcg/L, p < 0.001. In a univariate analysis, serum chromium level was associated with PD modality: Exp (B) 7.46 (95% confidence interval [CI] 2.1 - 26.4), p = 0.002. The association of PD modality with serum chromium level was even more significant using a multivariate logistic regression model: odds ratio (OR) 11.87 (95% CI 2.85 - 49.52), p = 0.001 after adjustment for age, gender, diabetes, smoking, dialysis vintage, use of diuretics, and residual renal function.Conclusions:In patients treated with chronic dialysis, serum chromium levels are higher in patients treated with PD than in those treated with HD.

Determining Serum Zinc and Magnesium Levels in Hemodialysis Patients Could be Helpful for Clinicians

Trace element determination is requested rarely for critically ill patients in Iran, due to the underestimation of the trace element determination by Iranian physicians. The aim was to compare the levels of Zn and Mg in a group of hemodialysis patients and normal individuals. This study shows that trace element determination is helpful for management of hemodialysis patients. Fifty-three hemodialysis patients and 51 control individuals were randomly analyzed for Zn and Mg serum levels. Comparison of before or after dialysis and with normal individuals was done and receiver operating characteristics (ROC) curves were plotted to evaluate the analytical sensitivity and specificity of Zn and Mg determination. Confidence interval for all statistical methods was 95 %. Zinc serum levels were decreased after hemodialysis insignificantly (P = 0.201) but Mg levels were decreased significantly (P = 0.000). Both Zn and Mg levels, before and after hemodialysis were meaningfully lower than normal controls (P < 0.05). ROC analysis showed that the area under the curve was high for Zn levels both before and after hemodialysis but it was high for Mg only before hemodialysis. Current study shows that serum Zn and Mg measurements can have clinical importance. Both before and after hemodialysis, serum Zn = 297.5 µg/L and Mg = 2.295 µg/L are proposed as cut-off values with about 90 % specificity, for monitoring of these two element in hemodialysis patients. It is suggested that clinicians consider the measurement of these trace elements for hemodialysis patients routinely or periodically as clinical chemistry tests.

Comparative Study on Trace Element Excretions between Nonanuric and Anuric Patients Undergoing Continuous Ambulatory Peritoneal Dialysis

Few studies have been reported on alterations of trace elements (TE) in peritoneal dialysis patients. Our objective was to investigate and assess the characteristics of daily TE excretions in continuous ambulatory peritoneal dialysis (CAPD) patients. This cross-sectional study included 61 CAPD patients (nonanuric/anuric: 45/16) and 11 healthy subjects in Wuhan, China between 2013 and 2014. The dialysate and urine of patients and urine of healthy subjects were collected. The concentrations of copper (Cu), zinc (Zn), selenium (Se), molybdenum (Mo), and arsenic (As) in dialysate and urine were determined using inductively coupled plasma mass spectrometer (ICP-MS). Various clinical variables were obtained from automatic biochemical analyzer. Daily Cu, Zn, Se, and Mo excretions in nonanuric patients were higher than healthy subjects, while arsenic excretion in anuric patients was lower. A strong and positive correlation was observed between Se and Mo excretion in both dialysate (β = 0.869, p < 0.010) and urine (β = 0.968, p < 0.010). Furthermore, the clinical variables associated with Se excretion were found to be correlated with Mo excretion. Our findings indicated that nonanuric CAPD patients may suffer from deficiency of some essential TEs, while anuric patients are at risk of arsenic accumulation. A close association between Se and Mo excretion was also found.

Oxocomplexes of Mo(VI) and W(VI) with 8-hydroxyquinoline-5-sulfonate in solution: structural studies and the effect of the metal ion on the photophysical behaviour

Multinuclear ((1)H, (13)C, (95)Mo and (183)W) NMR spectroscopy, combined with DFT calculations, provides detailed information on the complexation between the Mo(VI) and W(VI) oxoions and 8-hydroxyquinoline-5-sulfonate (8-HQS) in aqueous solution. Over the concentration region studied, Mo(VI) and W(VI) oxoions form three homologous complexes with 8-HQS in water in the pH range 2-8. Two of these, detected at pH < 6, are mononuclear 1 : 2 (metal : ligand) isomers, with the metal centre (MO2(2+)) coordinated to two 8-HQS ligands. An additional complex, dominant at slightly higher pH values (5-8) for solutions with a 1 : 1 metal : ligand molar ratio, has a binuclear M2O5(2+) centre coordinated to two 8-HQS ligands. The two metal atoms are bridged by three oxygen atoms, two coming from 8-HQS, together with the M-O-M bridge of the bimetallic centre. We show that the long-range exchange corrected BOP functional with local response dispersion (LCBOPLRD), together with explicit solvent molecules, leads to geometries that readily converge to equilibrium structures having realistic bridging O8-HQS-M bonds. Previous attempts to calculate the structures of such binuclear complexes using DFT with the B3LYP functional have failed due to difficulties in treating the weak interaction in these bridged structures. We believe that the LCBOPLRD method may be of more general application in theoretical studies in related binuclear metal complexes. UV/visible absorption and luminescence spectra of all the complexes have also been recorded. The complex between Mo(vi) and 8-HQS is only weakly luminescent, in contrast to what has been observed with this ligand and many other metal ions. We suggest that this is due to the presence of low-lying ligand-to-metal charge transfer (LMCT) states close to the emitting ligand-based level which quench the emission. However, with W(VI), DFT calculations show that the LMCT states are now much higher in energy than the ligand based levels, leading to a marked increase in fluorescence.

Serum Zn levels and Cu/Zn ratios worsen in hemodialysis patients, implying increased cardiovascular risk: a 2-year longitudinal study

The objective of this study was to analyze serum Zn and Cu concentrations and Cu/Zn ratios in 116 hemodialysis patients (HPs) over a 2-year longitudinal study at four time points (6-month intervals). The relation exerted on these values by 26 biochemical and nutritional indexes, the age and drug consumption of the patients, and the etiology of their disease were also evaluated. A healthy control group (n = 50) was also studied. Mean serum Zn concentrations were lower (p = 0.009) and the Cu/Zn ratios higher (p = 0.009) in HPs than in controls. Serum Cu levels in HP did not differ to those of controls. At all four sampling times, the mean serum Zn levels and Cu/Zn ratios were lower and higher, respectively, in HPs than in the controls. There was a significant reduction in serum Zn levels and an increase in Cu concentrations and Cu/Zn ratios in HPs from the second to the fourth sampling. Serum Zn levels of the HPs diminish with age older than 50 years. Serum Cu levels were significantly higher in patients consuming antihypercalcemic or anti-infarction drugs, whereas serum Cu levels and Cu/Zn ratios were significantly lower in those treated with diuretics. Diminished Zn levels were negatively correlated with low-density lipoprotein (LDL) cholesterol in HPs; however, enhanced Cu/Zn ratios were positively correlated with total cholesterol and LDL cholesterol. Both findings indicate an increased cardiovascular risk. We conclude that this study contributes the first evidence of a correlation between marked dyslipidemia and worsened Cu/Zn ratios in HPs, implying an increased risk of diseases associated with elevated oxidative stress, inflammation, and depressed immune function, such as cardiovascular diseases.

Preanalytical management: serum vacuum tubes validation for routine clinical chemistry

Introduction

The validation process is essential in accredited clinical laboratories. Aim of this study was to validate five kinds of serum vacuum tubes for routine clinical chemistry laboratory testing.

Materials and methods:

Blood specimens from 100 volunteers in five diff erent serum vacuum tubes (Tube I: VACUETTE^®, Tube II: LABOR IMPORT^®, Tube III: S-Monovette^®, Tube IV: SST^® and Tube V: SST II^®) were collected by a single, expert phlebotomist. The routine clinical chemistry tests were analyzed on cobas^® 6000 <c501> module. The significance of the diff erences between samples was assessed by paired Student’s t-test after checking for normality. The level of statistical significance was set at P < 0.005. Finally, the biases from Tube I, Tube II, Tube III, Tube IV and Tube V were compared with the current desirable quality specifications for bias (B), derived from biological variation.

Results and conclusions:

Basically, our validation will permit the laboratory or hospital managers to select the brand’s vacuum tubes validated according him/her technical or economical reasons, in order to perform the following laboratory tests: glucose, total cholesterol, high density lipoprotein-cholesterol, triglycerides, total protein, albumin, blood urea nitrogen, uric acid, alkaline phosphatise, aspartate aminotransferase, gamma-glutamyltransferase, lactate dehydrogenase, creatine kinase, total bilirubin, direct bilirubin, calcium, iron, sodium and potassium. On the contrary special attention will be required if the laboratory already performs creatinine, amylase, phosphate and magnesium determinations and the quality laboratory manager intend to change the serum tubes. We suggest that laboratory management should both standardize the procedures and frequently evaluate the quality of in vitro diagnostic devices.

Minerals in dialysis therapy: an introduction

The 180 l of glomerular filtrate formed each day contain some 1100 g (2.5 pounds) of sodium chloride, of which only 5-10 g are excreted in the urine--95% is reabsorbed by the tubules. Some 425 g (nearly a pound) of sodium bicarbonate and 145 g of glucose are filtered, and more than 99% of both are reabsorbed. Also filtered, only to be reabsorbed, are substantial quantities of potassium, calcium, magnesium, phosphate, sulfate, amino acids, vitamins, and many other substances valuable to the body. It is no exaggeration to say that the composition of the blood is determined not by what the mouth takes in but by what the kidneys keep: they are the master chemists of our internal environment, which, so to speak, they manufacture in reverse by working it over completely some fifteen times a day…Our bones, muscles, glands, even our brains are called upon to do only one kind of physiological work, but our kidneys are called upon to perform an innumerable variety of operations. Bones can break, muscles can atrophy, glands can loaf, even the brain can go to sleep, without immediately endangering our survival; but should the kidneys fail to manufacture the proper kind of blood neither bone, muscle, gland nor brain could carry on (1).