Selenium Concentration In Urine Research Articles

Urine selenium concentration is a useful biomarker for assessing population level selenium status

Plasma selenium (Se) concentration is an established population level biomarker of Se status, especially in Se-deficient populations. Previously observed correlations between dietary Se intake and urinary Se excretion suggest that urine Se concentration is also a potentially viable biomarker of Se status. However, there are only limited data on urine Se concentration among Se-deficient populations. Here, we test if urine is a viable biomarker for assessing Se status among a large sample of women and children in Malawi, most of whom are likely to be Se-deficient based on plasma Se status. Casual (spot) urine samples (n = 1406) were collected from a nationally representative sample of women of reproductive age (WRA, n =741) and school aged children (SAC, n=665) across Malawi as part of the 2015/16 Demographic and Health Survey. Selenium concentration in urine was determined using inductively coupled plasma mass spectrometry (ICP-MS). Urinary dilution corrections for specific gravity, osmolality, and creatinine were applied to adjust for hydration status. Plasma Se status had been measured for the same survey participants. There was between-cluster variation in urine Se concentration that corresponded with variation in plasma Se concentration, but not between households within a cluster, or between individuals within a household. Corrected urine Se concentrations explained more of the between-cluster variation in plasma Se concentration than uncorrected data. These results provide new evidence that urine may be used in the surveillance of Se status at the population level in some groups. This could be a cost-effective option if urine samples are already being collected for other assessments, such as for iodine status analysis as in the Malawi and other national Demographic and Health Surveys.

Selenium Concentration in Korean Patients with Thyroid Disease: a Preliminary Report

Background and Objectives: Selenium is an important trace element for thyroid hormone metabolism, and its deficiency can cause hypothyroidism. Serum selenium concentration is the best biomarker to reflect selenium intake and reserve, although other markers can reflect. Therefore, we preliminarily assessed serum and urine selenium concentrations in patients with thyroid disease compared to those of a healthy population. We also investigated the correlation between serum and urine selenium concentration, thyroid hormone and urinary iodine concentration (UIC). Materials and Methods: A total of 97 patients (32 men, 65 women, 52.4±14.7 years) with benign thyroid nodules or thyroid dysfunction who visited the Samsung Medical Center between 2008 and 2013 were included. Data for 175 healthy subjects provided by Lee et al. were used as the control. Serum T3, free T4, and thyroid stimulating hormone (TSH) were measured using commercialized RIA or IRMA kits. Serum/urine selenium and UIC were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Results: Median serum selenium concentration was 110 μg/L (95% CI, 73-156). Median urine selenium concentration was 66.3 μg/gCr (95% CI, 28.7-283.5). Compared to 175 healthy subjects (serum 84 μg/L [95% CI, 30-144], urine 34.5 μg/gCr [95% CI, 0.8-107.2]), serum and urine selenium concentrations of patients with thyroid disease were significantly higher than those of healthy subjects (p＜0.001). Serum selenium concentration was significantly correlated with urine selenium concentration after log transformation (r=0.88, p=0.022), but was not significantly correlated with UIC, T3, free T4 and TSH. Conclusion: Selenium concentrations of patients with thyroid disease were significantly higher than those of healthy subjects. Serum selenium concentration was significantly correlated with urine selenium concentration.

Biological monitoring of exposure and effects in workers employed in a selenium-processing plant

The aim of the study was to assess external and internal selenium exposure and potential biological effects in employees working in a selenium-processing plant. Twenty male employees of a selenium-processing plant (exposed) and 20 age-matched male individuals without occupational selenium exposure (controls) participated in the study. Exposure to selenium at the workplace was determined by personal air sampling. Internal exposure was assessed by measuring total selenium concentration in plasma after a workshift and after holidays as well as by measuring the selenium concentration in urine before and after shift and after holidays. The activity of glutathione peroxidase (GPx) in blood and the prothrombin time were determined as biological effect parameters. The exposure to selenium in the workplace air ranged from 8 to 950 µg/m(3) and exceeded in a large part current occupational exposure limits. The selenium levels in plasma samples of the exposed ranged from 49 to 182 µg/L during exposure and were significantly higher than the plasma levels observed after holidays as well as in the control group. The selenium concentration in pre- and post-shift urine samples did not differ significantly, and the average urinary selenium levels of the employees (18-1,104 µg/g creatinine) were significantly higher than those measured after holidays or determined in controls. Both the concentration of selenium in plasma and in urine did not correlate with the current external exposure of the employees at the workplace. However, we found a strong and significant association between the two biomonitoring parameters. In spite of the considerable high external exposure to elemental selenium, we did not find any effect on the GPx activity in blood as well as on the prothrombin time. Both the selenium levels in plasma and urine may be used as biological monitoring parameters for the assessment of chronic occupational exposure to selenium. Nevertheless, the toxicokinetics of the urinary excretion of selenium remain still unclear and require further investigations. Moreover, our findings emphasise the necessity of a re-evaluation of occupational exposure limits for elemental selenium and inorganic selenium compounds.

Selenocompounds in juvenile white sturgeon: Evaluating blood, tissue, and urine selenium concentrations after a single oral dose

Selenium (Se) is an essential micronutrient for all vertebrates, however, at environmental relevant levels, it is a potent toxin. In the San Francisco Bay-Delta, white sturgeon, an ancient Chondrostean fish of high ecological and economic value, is at risk to Se exposure. The present study is the first to examine the uptake, distribution, and excretion of various selenocompounds in white sturgeon. A combined technique of stomach intubation, dorsal aorta cannulation, and urinary catheterization was utilized, in this study, to characterize the short-term effects of Se in the forms of sodium-selenate (Selenate), sodium-selenite (Selenite), selenocystine (SeCys), l-selenomethionine (SeMet), Se-methylseleno-l-cysteine (MSeCys), and selenoyeast (SeYeast). An ecologically relevant dose of Se (∼500μg/kg body weight) was intubated into groups of 5 juvenile white sturgeon. Blood and urine samples were repeatedly collected over the 48h post intubation period and fish were sacrificed for Se tissue concentration and distribution at 48h. The tissue concentration and distribution, blood concentrations, and urinary elimination of Se significantly differ (p≤0.05) among forms. In general, organic selenocompounds maintain higher blood concentrations, with SeMeCys maintaining the highest area under the curve (66.3±8.7 and 9.3±1.0μgh/ml) and maximum Se concentration in blood (2.3±0.2 and 0.4±0.2μg/ml) in both the protein and non-protein bound fractions, respectively. Selenate, however, did not result in significant increase of Se concentration, compared with the control, in the protein-bound blood fraction. Regardless of source, Se is preferentially distributed into metabolically active tissues, with the SeMet treated fish achieving the highest concentration in most tissues. In contrast, Selenite has very similar blood concentrations and tissue distribution profile to SeCys and SeYeast. From blood and tissue Se concentrations, Selenate is not stored in blood, but taken up rapidly by the liver and white muscle. Urinary elimination of Se is form dependent and peaks between 3 and 12h post intubation. A basic understanding of the overall Se absorption, distribution, and elimination is provided through monitoring tissue Se concentrations, however, conclusions regarding to the dynamics and the specific processes of Se metabolism can only be inferred, in the absence of kinetic information.

Urinary selenium excretion in selenite-loaded sheep and subsequent Se dynamics in blood constituents

Renal selenium excretion in sheep was measured during intravenous infusion of sodium selenite, and the post-infusion dynamics of Se levels in whole blood, plasma and red blood cells (RBC) were investigated for the next 5 days. The plasma Se level increased almost twenty fold with the infusion of Na2SeO3 (from 0.39 +/- 0.02 to 7.83 +/- 0.33 micromol x L(-1), P < 0.001) compared with the baseline value. The selenium concentration in urine (0.07 +/- 0.02 vs. 18.53 +/- 2.56 micromol x L(-1), P < 0.001), the amount of Se excreted (0.14 +/- 0.07 vs. 21.40 +/- 2.31 nmol x min(-1), P < 0.001) and the renal clearance of Se (0.1 9 +/- 0.03 vs. 3.01 +/- 0.34 mL x min(-1), P < 0.001) were found to be highly significantly elevated during selenite loading. The clearance measurements showed no changes in the urinary flow rate or in the glomerular filtration rate. During and at the end of infusion the highest Se level was attained in plasma, followed by whole blood and RBC. The plasma Se level fell rapidly within 10 min after the end of infusion, but the concentration of Se in RBC was stable up to the fourth hour, when it started to decrease too. On day 5 the Se concentrations in plasma, RBC and whole blood were found to be only slightly but still significantly higher than before the selenite infusion. The large disproportion between the infusion rate of Se (8.76 microg x min(-1)) and its renal excretion rate (1.69 microg x min(-1)) found in clearance measurements suggests low glomerular filtration of infused selenium, which might primarily be caused by the binding of selenite metabolites to blood constituents. The presented results confirm the low bioavailability to ruminants of Se from sodium selenite.

The urinary excretion of selenium in sheep treated with a vasopressin analogue.

The renal excretion of selenium was investigated in ewes with an excretion of hypotonic urine (control group) and in ewes with a formation of highly concentrated urine. Chronic stimulation of the urinary concentrating activity of sheep kidneys was induced by a long-term treatment with 1-desamino-8-D-arginine vasopressin (dDAVP), a synthetic analogue of vasopressin with prolonged effects. Young animals with 22 to 25 kg b.w. were fed a normal protein diet providing a daily intake of 129.25 g of crude protein, 12.03 MJ of digestible energy and 0.18 mg of selenium for 3 weeks. The vasopressin treated sheep (n = 11) were given subcutaneous injections of 12.5 micrograms of dDAVP in glycerol twice daily for one week before the clearance measurement of renal functions. The control group (n = 11) was treated with glycerol only. The administration of dDAVP resulted in a highly significant decrease of the urinary flow rate (from 3.19 +/- 0.50 in control group to 0.33 +/- 0.03 mL.min-1 in dDAVP animals, P < 0.001) without changes in the glomerular filtration rate (80.18 +/- 6.36 in controls vs. 77.86 +/- 6.26 mL.min-1, NS). No effects on plasma selenium level were observed (0.17 +/- 0.03 in controls vs. 0.20 +/- 0.03 mumol.L-1, NS) but the amounts of selenium excreted were found to be highly significantly reduced (from 0.29 +/- 0.05 in controls to 0.03 +/- 0.01 nmol.min-1, P < 0.001) in dDAVP treated sheep. Despite a large reduction in urinary flow rate, the selenium concentration in urine was actually the same in both groups (0.09 +/- 0.01 mumol.L-1) resulting in a sharp fall in the renal clearance of selenium (2.20 +/- 0.54 in controls vs. 0.18 +/- 0.03 mL.min-1, P < 0.01) due to dDAVP. This seems to be a consequence of the large increase in the selenium solvent drag induced by a vasopressin treatment. The results presented suggest that vasopressin may contribute to maintenance of the selenium balance in sheep via its effects on renal function.

Serum and Urine Selenium Concentrations in Patients with Cardiovascular Diseases and Relationship to Other Nutritional Indexes

Serum and urine selenium levels were determined in patients with cardiovascular diseases by hydride generation atomic absorption spectrometry. Mean serum Se concentrations measured in patients with acute myocardial infarction (AMI; n = 32) or with ischemic cardiomyopathy (n = 50) were significantly lower than those determined in control groups. In AMI patients, serum triglyceride levels showed a positive significant correlation with the serum Se concentration (r = 0.59, p < 0.05). This result reinforces the important role of Se as an antioxidant agent in this disease. Mean urine Se concentrations of AMI patients (n = 33) were also significantly lower to those determined in the control group (p < 0.05). This reaction of the organism contributes to regulate the Se homeostasis to keep the body Se status as high as possible.

Serum and urine selenium concentrations as indicators of body status in patients with diabetes mellitus

Serum and urine selenium levels were determined in patients with diabetes by hydride generation atomic absorption spectrometry. Mean serum selenium concentrations measured in patients with diabetes mellitus (64.9±22.8 μg/l) were significantly lower than those determined in the control group (74.9±27.3 μg/l) ( P<0.05). Mean serum selenium concentrations were not significantly different between the two groups of diabetic patients considered ( P>0.05). Mean urine selenium concentration in diabetic patients (18.8±10.7 μg/l) were not significantly different from those measured in the control group (20.2±10.1 μg/l) ( P>0.05). No significant differences in serum and urine selenium levels were found if related to sex of patients ( P>0.05). Application of linear regression analysis to serum and urine selenium levels and patients' age showed a non-statistically significant correlation ( P>0.05). Given the marked overlap between the two ranges of the populations, the predictive values of serum selenium in diabetic patients are low.

The Role of Selenium Deficiency in Dilated Cardiomyopathy in Saudi Arabia

Selenium deficiency is implicated in the etiology of endemic juvenile dilated cardiomyopathy in China, and in sporadic cases in other countries. The aim of this study was to evaluate the role of selenium deficiency in the pathophysiology of dilated cardiomyopathy in the Saudi Arabian population. Plasma and urine selenium concentrations from 72 Saudi patients with confirmed dilated cardiomyopathy were compared with corresponding values from 70 control subjects of the same national origin who had normal ventricular function. Plasma and urine selenium concentrations (mean+/-SD) were 1.347plusmn;0.45 and 0.49+/-0.37 micromol/L, respectively, for the patient group, and 1.32+/-0.41 and 0.60+/-0.41 micromol/L, respectively, for the control group. The differences in the values between the two groups were statistically insignificant. In the Saudi population, dilated cardiomyopathy is not caused by selenium deficiency.

Selenium, systemic immune response syndrome, sepsis, and outcome in critically ill patients.

To confirm early, marked decrease in plasma selenium concentrations in patients admitted to a surgical and medical intensive care unit (ICU), and to study this decrease according to the presence or absence of systemic inflammatory response syndrome (SIRS), sepsis, or direct ischemia-reperfusion. Prospective, observational study. Collaboration between the adult ICU of a 1,100-bed general hospital and a biochemical research laboratory of a university medical center. One hundred thirty-four consecutive surgical and medical ICU patients. None. In the first 31 patients, plasma and urine selenium concentrations were measured by electrothermal atomic absorption spectrometry on admission and once weekly during their ICU stay. These values were compared first with severity scores, criteria for SIRS, sepsis, and organ system failure taken on admission, and then with nosocomial infection, organ system failure during ICU stay, and hospital mortality. An early, low mean plasma selenium concentration was observed in these patients compared with selenium laboratory reference values. Plasma selenium, measured on ICU admission, inversely correlated with Acute Physiology and Chronic Health Evaluation II or Simplified Acute Physiology II scores. Patients with SIRS had lower selenium concentrations than those without SIRS. Mean urine selenium losses were normal in the first 31 patients. Plasma selenium concentration was low in all patients with severe sepsis and septic shock (range 0.20 to 0.72 micromol/L) and in those patients with ischemia-reperfusion from aortic cross-clamping (range 0.34 to 0.68 micromol/L). Despite recommended specific selenium supplementation, plasma selenium concentrations remained low for >2 wks in patients with SIRS. However, there was a slight increase in plasma selenium concentrations in surviving SIRS patients, whereas plasma selenium concentrations decreased in nonsurviving patients. The frequency of ventilator-associated pneumonia, organ system failure, and mortality was three times higher in patients with low plasma selenium concentration at the time of admission (selenium < or =0.70 micromol/L) than for the other patients. In severely ill ICU patients with SIRS, we observed an early 40% decrease in plasma selenium concentrations, reaching values observed in deleterious nutritional selenium deficiency. This prolonged decrease in selenium concentrations could explain the three-fold increase in morbidity and mortality rates in these patients compared with other ICU patients. The efficacy of selenium treatment in SIRS patients with a high gravity index score or hypoperfusion needs further investigation.

Relationship between the cervical uterine cancer evolution and selenium concentration in urine determied by NAA

Neutron activation analysis of Se in urine reaches an optimum sensitivity (few ppb) and precision (±12%) when the traces are complexed without using a carrier by ammonium pryrrolidindithiocarbamate (APDC) at pH 1.5–2 and adsorbed on activated carbon filters. In this way the selenium traces analysis have been carried out through77mSe in 45 urine samples on a pre-separation basis by cyclic activation ofthe carbon filters. The selenium concentration in our blanks is virtually zero, because APDC proved to be selnium free and selenium mass in 50 mg of activated carbon used as a filter is 20 times below our qualitative detection limit and 144 times below our quantitative detection limit. The samples were first of day urine from healthy and ill women suffering cervical uterine cancer, at different evolution stages: incipient, intemediate and advanced, with no treatment, and surgery, radiotherapy, chemotherapy, or a combined treatment. The results show a consistent tred to increase the selenium trace concentration during the intemediate stage, whereas it is the same than nomal for incipient cases, and it decreases to the lowest concentrations for advanced cases.

Evaluation of selenium exposure in copper refinery workers.

Concentrations of selenium in plasma and urine and activity of glutathione peroxidase in erythrocytes were determined in workers exposed to selenium and in a control group. Plasma selenium concentrations were significantly lower in exposed workers compared to the controls. Erythrocyte glutathione peroxidase activity in selenium workers was significantly higher than in the control subjects. Urine selenium concentrations were not statistically different between the two groups. There was a significant positive correlation between plasma selenium concentrations and urine selenium concentrations in workers exposed to selenium. A weak significant positive correlation was found between plasma selenium concentrations and erythrocyte glutathione peroxidase activity in exposed workers. Our results suggest that the lower plasma selenium concentrations in selenium workers may be attributed to an increase of urinary selenium excretion.