Plasma selenium status in a group of Australian blood donors and fresh blood components

Trace Element Analysis in Whole Blood and Plasma for Reference Levels in a Selected Queensland Population, Australia

The levels of trace elements in whole blood and plasma have been widely used for assessing nutritional status and monitoring exposure and can vary widely in populations from different geographical regions. In this study, whole blood samples (n = 120) and plasma samples (n = 120) were obtained from healthy donors attending the Red Cross Blood Bank (Queensland Red Cross Blood Service), which provided information for age and sex. There were 71 males (age range: 19-73 years) and 49 females (age range: 18-72 years) for whole blood samples, and 59 males (age range: 19-81 years) and 61 females (age range: 19-73 years) for plasma samples. The main aim of the study was to provide information on blood reference levels of 21 trace elements (Ag, Al, As, Bi, Br, Cd, Co, Cr, Cu, Hg, I, Mn, Mo, Ni, Pb, Sb, Se, Tl, U, V, Zn) in Queensland. The study also aimed to assess differences in trace element blood levels between males and females and the effect of age. The trace element levels in blood samples were analysed using inductively coupled plasma mass spectrometry (ICP-MS) and the standard reference materials of Seronorm (Trace Elements Whole Blood) and UTAK (Trace Elements Serum) were used for quality control and assurance. The study found wide variations of trace element levels in whole blood and plasma, and generally the levels were comparable to other countries. No detectable levels were found for Bi, Cr, U and V in whole blood, but V levels were found in plasma samples. There were significant differences between males and females for whole blood Cu (p < 0.001), I (p = 0.009), Tl (p = 0.016) and Zn (p = 0.016). Significant differences were also found for plasma Cu (p < 0.001) and Se (p = 0.003) between males and females. There were trends of increased levels of blood Pb, Se and Zn with age. The study has provided further information on a wide range of trace elements in blood as reference levels for Queensland and Australia which are currently lacking.

Sodium, Magnesium, Calcium, Manganese, Iron, Copper, and Zinc in Serums of Beta Thalassemia Major Patients

Thalassemia major is the most severe form of thalassemia and occurs with the impaired synthesis of β-globin which causes the accumulation of unpaired alpha globin chain. Patients with beta thalassemia major can only survive with periodically safe blood transfusions leading to the accumulation of iron in the bloods of patients, and this causes several endocrinopathies. Although iron overload in thalassemic patients has been extensively studied, there is little information about the levels of other trace elements. The aim of this study was to investigate the differences of serum concentrations of sodium, magnesium, calcium, manganese, iron, copper, and zinc for patients with major β-thalassemia. Concentration of elements was determined by inductively coupled plasma-mass spectrometry system. The statistical difference between the elemental concentrations of the patient and control groups was found by the Mann-Whitney U test. In addition, the relationship between concentrations of the measured elements for each group was determined by the Spearman correlation test. The results revealed that iron, zinc, magnesium, and manganese serum levels of thalassemic patients were significantly higher than the control group while calcium concentration was statistically lower than the control group. There was no significant difference observed for copper and sodium levels of patients when compared to the healthy control group.

Serum Selenium Status and Its Interrelationship with Serum Biomarkers of Thyroid Function and Antioxidant Defense in Hashimoto's Thyroiditis

Selenium (Se) deficiency has been implicated in the pathogenesis of Hashimoto’s thyroiditis (HT), although the available evidence is limited. The present study aimed to explore the interrelationships between serum Se status with measures of thyroid function and antioxidant defense in new cases of HT patients with hypoechogenic thyroid. HT patients (n = 49) and matched controls (n = 50) were recruited. Selenium, thyroid hormone panel, thyroid volume (TVol), glutathione (GSH), glutathione peroxidase3 (GPx3) activity, urinary iodine concentration (UIC), and urinary creatinine (Cr) were assessed. HT patients exhibited lower Se levels compared to controls (p < 0.001) with the rates of Se-deficient (<0.85 µmol/L) participants being 58.8% and 34%, respectively. Se-deficient patients exhibited higher thyroid stimulating hormone (TSH), Thyroid volume (TVol), thyroglobulin, antibody-titers, GPx3 activity and UIC/Cr compared to Se-sufficient patients (all p < 0.001). In the Se-deficient patients, inverse correlations were seen between Se-levels with TSH, TVol, and Thyroid peroxidase antibody (TPO-Ab) (all p < 0.001). This study is the first to uncover that coexisting Se-deficiency and elevated iodine in HT may enhance autoimmune reactions and accelerate the deterioration of thyroid function through oxidative stress. Our study also highlights the importance of optimal Se status in this disease, thus providing a rationale for the execution of intervention trials for the evaluation of the clinical benefits of antioxidant-status improvement in HT.

Selenium Status Is Not Associated with Cognitive Performance: A Cross-Sectional Study in 154 Older Australian Adults

Selenium was suggested to play a role in modulating cognitive performance and dementia risk. Thus, this study aimed to investigate the association between selenium status and cognitive performance, as well as inflammatory and neurotrophic markers in healthy older adults. This cross-sectional study included 154 older adults (≥60 years) from Victoria, Australia. Participants were assessed for cognitive performance (Cogstate battery), dietary selenium intake (two 24-h food recalls), plasma selenium concentration, inflammatory markers (interleukin (IL)-6, -8, -10, tumor necrosis factor-alpha and adiponectin) and neurotrophic factors (brain-derived neurotrophic factor, vascular endothelial growth factor and insulin-like growth factor 1). Dietary selenium intake was adequate for 85% of all participants. The prevalence of selenium deficiency was low; only 8.4% did not have the minimum concentration in plasma required for optimization of iodothyronine 5' deiodinases activity. Multiple linear regression analysis revealed that plasma selenium was not associated with cognitive performance, inflammatory markers nor neurotrophic factors, independent of age, sex, body mass index (BMI), habitual physical activity, APOE status, education, and history of cardiovascular disease. The lack of association might be due to the optimization of selenoproteins synthesis as a result of adequate selenium intake. Future prospective studies are recommended to explore potential associations of selenium status with age-associated cognitive decline.

Selenium Levels in Serum, Red Blood Cells, and Cerebrospinal Fluid of Alzheimer's Disease Patients: A Report from the Australian Imaging, Biomarker & Lifestyle Flagship Study of Ageing (AIBL)

Selenium (Se) protects cells against oxidative stress damage through a range of bioactive selenoproteins. Increased oxidative stress is a prominent feature of Alzheimer's disease (AD), and previous studies have shown that Se deficiency is associated with age-related cognitive decline. In this study, we assessed Se status in different biofluids from a subgroup of participants in the Australian Imaging, Biomarkers and Lifestyle Flagship Study of Ageing. As Se in humans can either be an active component of selenoproteins or inactive via non-specific incorporation into other proteins, we used both size exclusion chromatography-inductively coupled plasma-mass spectrometry (SEC-ICP-MS) and tandem mass spectrometry to characterize selenoproteins in serum. We observed no differences in total Se concentration in serum or cerebrospinal fluid of AD subjects compared to mildly cognitively impairment patients and healthy controls. However, Se levels in erythrocytes were decreased in AD compared to controls. SEC-ICP-MS analysis revealed a dominant Se-containing fraction. This fraction was subjected to standard protein purification and a bottom-up proteomics approach to confirm that the abundant Se in the fraction was due, in part, to selenoprotein P. The lack of change in the Se level is at odds with our previous observations in a Brazilian population deficient in Se, and we attribute this to the Australian cohort being Se-replete.

Serum selenium and selenoprotein-P levels in autoimmune thyroid diseases patients in a select center: a transversal study

OBJECTIVE

Selenium (Se) supplementation has been used to help prevent the progression of Graves' ophthalmopathy (GO) and autoimmune thyroid diseases (AITD) patients. We investigated Se serum and selenoprotein P (SePP) levels in Graves' disease (GD) with and without GO, Hashimoto's thyroiditis (HT) patients and in 27 control individuals (C).

SUBJECTS AND METHODS

We studied 54 female and 19 male patients: 19 with GD without GO, 21 GD with GO, 14 with HT and 19 with HT+LT4. Se values were measured using graphite furnace atomic absorption spectrophotometry. Serum SePP levels were measured by ELISA.

RESULTS

Median Se levels were similar among all groups; GD patients: 54.2 (46.5-61.1 μg/L), GO: 53.6 (43.5-60.0 μg/L), HT: 51.9 (44.6-58.5 μg/L), HT+LT4 54.4 (44-63.4) and C group patients: 56.0 (52.4-61.5 μg/L); P = 0.48. However, serum SePP was lower in GO patients: 0.30 (0.15-1.05 μg/mL) and in HT patients: 0.35 (0.2-1.17 μg/mL) compared to C group patients: 1.00 (0.564.21 μg/mL) as well as to GD patients: 1.19 (0.62-2.5 μg/mL) and HT+LT4 patients: 0.7 (0,25-1.95); P = 0.002. Linear regression analysis showed a significant relationship between SePP and TPOAb values (r = 0.445, R2 = 0.293; P < 0.0001). Multiple regression analysis found no independent variables related to Se or SePP.

CONCLUSION

A serum Se concentration was lower than in some other countries, but not significantly among AITD patients. The low serum SePP levels in GO and HT patients seems to express inflammatory reactions with a subsequent increase in Se-dependent protein consumption remains unclear.

High levels of plasma selenium are associated with metabolic syndrome and elevated fasting plasma glucose in a Chinese population: A case-control study

BACKGROUND

Selenium is important for human health and involved in various metabolic processes. Deficiency of selenium associates with increased risk for cancer and cardiovascular diseases. There has been an increase use of selenium supplements for the treatment of autoimmune thyroid conditions. However, the potential biological effects of selenium overload arouse the public concern. The aim of this study was to investigate the associations of plasma selenium concentrations of adults with metabolic syndrome (MS) in Chinese population.

METHODS

A matched case-control study including 204 metabolic syndrome patients and 204 healthy controls was conducted in 2012. The MS cases were defined according to the criteria of Chinese Diabetes Society (CDS). Healthy controls without abnormality of metabolic components were matched with cases in age, gender and region. Plasma concentrations of selenium were determined by graphite furnace atomic absorption spectrometry (GFAAS). Fasting plasma glucose (FPG), total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL), and low density lipoprotein cholesterol (LDL) were detected by automatic biochemical analyzer.

RESULTS

The median levels of plasma selenium in MS group were 146.3 (107.3-199.4)μg/L, which were significantly higher than that in the control group (127.4: 95.7-176.0)μg/L; Plasma levels of selenium were related to the risk of MS in dose-response manner. Risk of MS was significantly higher in subjects with plasma selenium in the highest tertile (T3: ≥176.0μg/L) compared to those in the lowest tertile (T1: <95.7μg/L) [odds ratio (OR)=2.416 (95% CI: 1.289-4.526)]. The plasma levels of selenium were positively correlated with fasting plasma glucose (FPG) (rs=0.268, P<0.001). Plasma selenium at the median (T2: 95.7-176.0μg/L) or upper tertile (T3: ≥176.0μg/L) was associated with increased risk of elevated FPG (defined by FPG≥6.1mmol/L) as compared with the lowest tertile (T1: ≤95.7μg/L) [T2 vs. T1, OR=3.487 (1.738-6.996); T3 vs. T1, OR=6.245 (3.005-12.981)].

CONCLUSIONS

Higher levels of plasma selenium might increase the risk of metabolic syndrome and elevated fasting plasma glucose. Selenium supplements should be used with prudence for CVD and cancer prevention.

The impact of acute lung injury, ECMO and transfusion on oxidative stress and plasma selenium levels in an ovine model

The purpose of this study was to determine the effects of smoke induced acute lung injury (S-ALI), extracorporeal membrane oxygenation (ECMO) and transfusion on oxidative stress and plasma selenium levels. Forty ewes were divided into (i) healthy control (n=4), (ii) S-ALI control (n=7), (iii) ECMO control (n=7), (iv) S-ALI+ECMO (n=8) and (v) S-ALI+ECMO+packed red blood cell (PRBC) transfusion (n=14). Plasma thiobarbituric acid reactive substances (TBARS), selenium and glutathione peroxidase (GPx) activity were analysed at baseline, after smoke injury (or sham) and 0.25, 1, 2, 6, 7, 12 and 24h after initiation of ECMO. Peak TBARS levels were similar across all groups. Plasma selenium decreased by 54% in S-ALI sheep (1.36±0.20 to 0.63±0.27μmol/L, p<0.0001), and 72% in sheep with S-ALI+ECMO at 24h (1.36±0.20 to 0.38±0.19, p<0.0001). PRBC transfusion had no effect on TBARS, selenium levels or glutathione peroxidase activity in plasma. While ECMO independently increased TBARS in healthy sheep to levels which were similar to the S-ALI control, the addition of ECMO after S-ALI caused a negligible increase in TBARS. This suggests that the initial lung injury was the predominant feature in the TBARS response. In contrast, the addition of ECMO in S-ALI sheep exacerbated reductions in plasma selenium beyond that of S-ALI or ECMO alone. Clinical studies are needed to confirm the extent and duration of selenium loss associated with ECMO.