Determination of toxic and essential trace elements in serum of healthy and hypothyroid respondents by ICP-MS: A chemometric approach for discrimination of hypothyroidism

Trace element status in canine endocrine diseases

A balanced trace element status is essential for the optimal functioning of all organisms. However, their concentrations are often altered in diverse medical conditions. This study investigated the trace element profiles in plasma samples of dogs with endocrine diseases and used chemometric techniques to explore their associations with biochemical data. Thirteen elements (As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se and Zn) were measured in 40 dogs with hyperadrenocorticism (HAC), 29 dogs with diabetes mellitus (DM), 11 dogs with hypothyroidism (HT) and 30 control dogs using inductively coupled plasma mass spectrometry (ICP-MS). Statistically significant differences were observed for As, Cu, Mo, Se and Zn. In comparison with the control group, the HT patients had higher As and lower Se levels, while the HAC group had higher concentrations of Mo. All three disease groups had higher Cu and Zn concentrations than the control group, with the DM group having higher Cu concentrations and the HAC group higher Zn concentrations than the other endocrinopathy groups. The chemometric analysis revealed distinctive association patterns for discriminating each pathology group and the control group. Moreover, the analysis revealed the following associations: Mo with glucose levels and Cu with fructosamine levels in the DM group, As with cortisol levels in the HAC group, and Se with TT4 levels and As with TSH levels in the HT group. The study findings provide valuable insights into the complex relationships between trace elements and endocrinopathies, elucidating the associations with biochemical markers in these diseases. Larger-scale studies are necessary to fully understand the observed relationships and explore the potential clinical applications.

A simple, rapid method for simultaneous determination of multiple elements in serum by using an ICP-MS equipped with collision cell

We developed an inductively coupled plasma mass spectrometry method for testing 23 elements, namely, Mg, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Cd, Sn, Sb, Ba, W, Tl, Pb, and U, in human serum. The serum samples were analyzed after diluting 1/25 with 0.5% nitric acid, 0.02% Triton-X-100, and 2% methanol. Sc, In, Y, Tb, and Bi were assigned internal standards to correct the baseline drift and matrix interference. The kinetic energy discrimination mode of the instrument with helium gas as the collision gas eliminated polyatomic interference. All 23 elements exhibited excellent linearity in their testing range, with a coefficient of determination ≥ 0.9996. The limits of detection of the 23 elements were within the range of 0.0004-0.2232 µg/L. The intra- and inter-day precision (relative standard deviation) were < 12.19%. The recoveries of the spiked standard for all elements were 88.98-109.86%. Among the 23 elements of the serum reference materials, the measured results of Mg, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, and Se were within the specified range of the certificate, and the results of the other elements were also satisfactory. The developed method was simple, rapid, and effective, and only 60 μL sample was consumed. A total of 1000 serum samples from healthy individuals were randomly selected from the Henan Rural Cohort, which reflects the status of serum elements in rural adults from the Northern Henan province of central China.

Analysis of essential, toxic, rare earth, and noble elements in maternal and umbilical cord blood

Progressive industrialization in recent decades has contributed to the increase of metal levels in the environment, which has a dangerous impact on human health, primarily pregnant women. In this study, we aimed to compare levels of various elements in maternal and umbilical cord (UC) plasma samples collected from 125 healthy pregnant women, conduct correlation analysis among paired plasma samples, and compare our data with other populations worldwide. The study design included the following elements: essential (Mn, Co, Cu, Zn, Se, Mo), non-essential (Be, Al, Ni, As, Rb, Sr, Cd, Sb, Pb, U), rare earth (La, Pr, Ce, Nd, Sm, Eu, Gd, Dy, Ho, Er), and noble metals (Ru, Rh, Re, Pt). Levels of 30 elements were higher in maternal plasma than in UC plasma samples. However, no disparities at the statistically significant level were found for Be, Zn, Rb, Cd, Ce, and Ho. Correlation analysis among paired plasma samples revealed only positive/synergistic correlations of different strengths between most elements. Compared to other countries across the globe, our participants had considerably lower plasma levels of Zn and higher levels of Co, Ni, and As. This study provides not only a new and deeper comprehension, but also the first insight into the levels, correlation, distribution, and potential transplacental transfer of 30 elements.

Trace elements and the thyroid

Trace elements, such as iodine and selenium (Se), are vital to human health and play an essential role in metabolism. They are also important to thyroid metabolism and function, and correlate with thyroid autoimmunity and tumors. Other minerals such as iron (Ir), lithium (Li), copper (Co), zinc (Zn), manganese (Mn), magnesium (Mg), cadmium (Cd), and molybdenum (Mo), may related to thyroid function and disease. Normal thyroid function depends on a variety of trace elements for thyroid hormone synthesis and metabolism. These trace elements interact with each other and are in a dynamic balance. However, this balance may be disturbed by the excess or deficiency of one or more elements, leading to abnormal thyroid function and the promotion of autoimmune thyroid diseases and thyroid tumors.The relationship between trace elements and thyroid disorders is still unclear, and further research is needed to clarify this issue and improve our understanding of how trace elements mediate thyroid function and metabolism. This paper systematically reviewed recently published literature on the relationship between various trace elements and thyroid function to provide a preliminary theoretical basis for future research.

Effects of storage conditions on the stability and distribution of clinical trace elements in whole blood and plasma: Application of ICP-MS

BACKGROUND

Knowledge of trace element stability during sample handling and preservation is a prerequisite to produce reliable test results in clinical trace element analysis.

METHOD

An alkaline dissolution method has been developed using inductively coupled plasma mass spectrometry to quantify eighteen trace element concentrations: vanadium, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, bromine, molybdenum, cadmium, antimony, iodine, mercury, thallium, lead, and bismuth in human blood, using a small sample volume of 0.1 mL. The study evaluated the comparative effects of storage conditions on the stability of nutritionally essential and non-essential elements in human blood and plasma samples stored at three different temperatures (4 °C, -20 °C and -80 °C) over a one-year period, and analysed at multiple time points. The distribution of these elements between whole blood and plasma and their distribution relationships are illustrated using blood samples from 66 adult donors in Queensland.

RESULTS

The refrigeration and freezing of blood and plasma specimens proved to be suitable storage conditions for many of the trace elements for periods up to six months, with essentially unchanged concentrations. Substantially consistent recoveries were obtained by preserving specimens at -20 °C for up to one year. Ultra-freezing of the specimens at -80 °C did not improve stability; but appeared to result in adsorption and/or precipitation of some elements, accompanied by a longer sample thawing time. A population sample study revealed significant differences between the blood and plasma concentrations of six essential elements and their relationships also varied significantly for different elements.

CONCLUSION

Blood and plasma specimens can be reliably stored at 4 °C for six months or kept frozen at -20 °C up to one year to obtain high quality test results of trace elements.

Zinc Deficiency, Plasma Fatty Acid Profile and Desaturase Activities in Hemodialysis Patients: Is Supplementation Necessary?

Background: Desaturation and elongation are critical processes in endogenous metabolic fatty acid pathways. Zinc (Zn) is a cofactor for desaturases and elongases enzymes. There is limited evidence regarding the relationships between biomarkers of Zn status, nutritional intake, plasma phospholipid fatty acid profile and clinical outcomes among patients undergoing hemodialysis (HD). Objective: To examine the relationships between dietary and serum levels of Zn and Cu/Zn ratio and to explore associations of these micronutrients with PUFA profile and estimated desaturase and elongase enzyme activities in serum phospholipids among HD patients. Methods: This study included 40 adult patients undergoing hemodialysis treatment. Repeated 24-h recalls were applied for dietary intake assessment. Serum concentration of Zn and Cu were determined using inductively coupled plasma mass spectrometry and fatty acid composition by gas-liquid chromatography. Desaturase and elongase activities were calculated from product-precursor fatty acid ratios. Results: Inadequate dietary Zn intake was found in 55% of HD patients. They all had serum Zn concentration below the reference value of 60 μg/dL (mean 38.8 ± 7.72 μg/dL). Adequate zinc intake was accompanied with significantly higher intake of energy, total fats, SFA, MUFA and proteins. There was no correlation between Zn serum status and Zn intake estimates. Serum Cu/Zn ratio was high, (2.76 ± 0.68), directly and significantly associated with HD period, CRP, BMI, VFA, and inversely with Kt/V, albumin, iron, and iPTH. The n-6/n-3 ratio in plasma phospholipids was elevated (12.25 ± 3.45) and patients with inadequate Zn intake had lower n-3 PUFA intake and status compared to those with adequate intake. Serum Zn concentrations were inversely correlated with linoleic/dihomo-γ-linolenic acid ratio (LA/DGLA) (p = 0.037), related to D6-desaturase activity (p = 0.033) and directly with DGLA relative abundances (p = 0.024). Cu status was inversely associated with EPA level (p = 0.03) and estimates of elongase activity (p = 0.001). Furthermore, positive relationship was found between the Cu/Zn ratio and determined elongase value (p = 0.01). Conclusion: Findings of this study underpin the high prevalence of Zn deficiency and inadequate n-3 PUFA intake and status among subjects undergoing HD. The results obtained indicate that the assessment of Zn status should be a standard parameter of nutritional status screening in HD patients while emphasizing the importance of Cu/Zn determination. Although further research is warranted, Zn and-n-3 PUFA supplementation in HD patients might be beneficial for the prevention and attenuation of adverse health outcomes.

Selected Essential and Toxic Chemical Elements in Hypothyroidism-A Literature Review (2001-2021)

Thyroid hormones are known for controlling metabolism of lipids, carbohydrates, proteins, minerals, and electrolytes and for regulating body temperature. Normal thyroid status depends on the chemical/elemental composition of body fluids and tissues, which changes depending on physiological state, lifestyle and environment. A deficiency or excess of certain essential chemical elements (selenium, zinc, copper, iron or fluorine) or exposure to toxic (cadmium or lead) or potentially toxic elements (manganese or chromium) interacts with thyroid hormone synthesis and may disturb thyroid homeostasis. In our review, accessible databases (Scopus, PubMed and Web of Science) were searched for articles from 2001-2021 on the influence of selected chemical elements on the development of hypothyroidism. Our review adopted some of the strengths of a systematic review. After non-eligible reports were rejected, 29 remaining articles were reviewed. The review found that disruption of the physiological levels of elements in the body adversely affects the functioning of cells and tissues, which can lead to the development of disease.

Analytical potential of total reflection X-ray fluorescence spectrometry for simultaneous determination of iron, copper and zinc in human blood serum and plasma

Due to many roles of trace elements such as Fe, Cu and Zn in various physiological and pathophysiological processes, their determination in serum and plasma is of high clinical relevance. In the present study, for the first time, the effect of serum and plasma preparation parameters (dilution factor and sample deposition volume) on the quality of results obtained by TXRF analysis was evaluated by means of experimental design tools (response surface analysis). It was found that the best strategy was the direct analysis of both human fluids without a previous dilution step. The accuracy and precision of the proposed methods were evaluated by analysis of reference materials (ClinChek® Plasma Control Level II and Seronorm™ Trace Elements Serum L-1). TXRF results agreed with the reference values and no significant differences at 95% confidence level were found. Limits of detection for the elements of interest were also adequate, taking into account their typical concentration ranges in real serum and plasma samples. Finally, the developed TXRF methods were applied to a set of serum and plasma samples from patients with different genders, ages and diagnoses, previously analysed by ICP-OES and ICP-MS techniques. The results showed good agreement between both analytical approaches. These results suggest that the proposed TXRF method provides reliable results thus being suitable for plasma and serum analysis, but in a simpler and more sustainable way.

Development and Validation of an ICP-MS Method and Its Application to Determine Multiple Trace Elements in Small Volumes of Whole Blood and Plasma

Essential and nonessential element concentrations in human blood provide important information on the nutritional status of individuals and can assist in the screening or diagnosis of certain disorders and their association with other causative factors. A simple and sensitive method, suitable for use with small sample volumes, for quantification of multiple trace element concentrations in whole blood and plasma has been developed using inductively coupled plasma-mass spectrometry. Method validation was performed using standard reference materials of whole blood and serum using varying sample treatments with nitric acid, water and hydrogen peroxide. The method was applied to quantify the trace element concentrations in whole blood and plasma samples (0.1 mL) from 50 adult blood donors in Queensland. The whole blood sample (5 mL) was collected in Vacutainer tubes with K2EDTA as anticoagulant. The developed method was able to quantify, in blood and plasma samples over a wide range of concentrations, several essential elements: cobalt, copper, zinc, iron, manganese and selenium; the nutritionally probably essential elements vanadium and strontium; and nonessential elements including lead, cadmium, arsenic, caesium, barium, thallium and uranium. Significant differences (P < 0.0001) were observed between whole blood and plasma concentrations for 13 elements; 5 of the measured elements, cobalt (0.49 vs. 0.36 μg/L), copper (1.0 vs. 0.75 mg/L), strontium (28 vs. 16 μg/L), barium (1.5 vs. 0.64 μg/L) and thallium (0.06 vs. 0.03 μg/L), had higher mean concentrations in plasma than in blood. Whole blood concentrations of nine trace elements were significantly correlated (P < 0.0001) with plasma concentrations. The distribution of the trace elements between human blood and plasma varied considerably for the different elements. These results indicate that, using a small sample volume, this assay is suitable for the evaluation of nutritional status as well as in monitoring human toxic elemental exposures.

Update of the risk assessment of nickel in food and drinking water

The European Commission asked EFSA to update its previous Opinion on nickel in food and drinking water, taking into account new occurrence data, the updated benchmark dose (BMD) Guidance and newly available scientific information. More than 47,000 analytical results on the occurrence of nickel were used for calculating chronic and acute dietary exposure. An increased incidence of post-implantation loss in rats was identified as the critical effect for the risk characterisation of chronic oral exposure and a BMDL 10 of 1.3 mg Ni/kg body weight (bw) per day was selected as the reference point for the establishment of a tolerable daily intake (TDI) of 13 μg/kg bw. Eczematous flare-up reactions in the skin elicited in nickel-sensitised humans, a condition known as systemic contact dermatitis, was identified as the critical effect for the risk characterisation of acute oral exposure. A BMDL could not be derived, and therefore, the lowest-observed-adverse-effect-level of 4.3 μg Ni/kg bw was selected as the reference point. The margin of exposure (MOE) approach was applied and an MOE of 30 or higher was considered as being indicative of a low health concern. The mean lower bound (LB)/upper bound (UB) chronic dietary exposure was below or at the level of the TDI. The 95th percentile LB/UB chronic dietary exposure was below the TDI in adolescents and in all adult age groups, but generally exceeded the TDI in toddlers and in other children, as well as in infants in some surveys. This may raise a health concern in these young age groups. The MOE values for the mean UB acute dietary exposure and for the 95th percentile UB raises a health concern for nickel-sensitised individuals. The MOE values for an acute scenario regarding consumption of a glass of water on an empty stomach do not raise a health concern.

Trace Element Status and Hypothyroidism: A Systematic Review and Meta-analysis

The relationship between thyroid hormones metabolism and trace element levels has biological plausibility; however, previous reports that compared trace element levels in patients with hypothyroidism and healthy individuals yielded conflicting results. Therefore, the aim of this meta-analysis was to investigate the association between selected trace elements (i.e., selenium (Se), zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), lead (Pb)), and magnesium (Mg) concentrations in patients with hypothyroidism and healthy controls. Electronic databases, including PubMed, Scopus, Embase, and Science Direct, were searched systematically until September 2019. Thirty-two observational studies were included in the final analyses. Hedges' g tests were used to estimate effect sizes, as trace element concentrations were reported using different measurement units across the studies. Selenium (Hedges' g = - 0.52; 95% CI = [- 1.05, - 0.002]; P = 0.049) and Zn (Hedges' g = - 0.86; 95% CI = [- 1.66, - 0.06]; P = 0.035) concentrations were significantly lower, whereas Pb concentrations were significantly higher (Hedges' g = 0.34; 95% CI = [0.10, 0.59]; P = 0.006) in patients with hypothyroidism compared with healthy controls. There were no differences in the concentrations of Fe, Cu, Mn, and Mg between the groups. Patients with hypothyroidism exhibited lower Se and Zn and increased Pb concentrations compared with healthy controls. High-quality studies with larger sample sizes are required to explicate the link between trace element status and hypothyroidism.

Thyroid dysfunction: how concentration of toxic and essential elements contribute to risk of hypothyroidism, hyperthyroidism, and thyroid cancer

This study was conducted to evaluate the levels of trace metals Fe, Cr, Co, Cd, Cu, Ni, Hg, Zn, and Pb in healthy individuals and patients with thyroid disease (hyperthyroidism, hypothyroidism, and cancerous). The serum levels of 110 participants living in Birjand City, east of Iran, were collected and analyzed using ICP-MS (Agilent 7900). Results showed that the concentration levels of Cr, Co, Zn, Cd, and Pb were significantly higher at case-patients (p < 0.05), but the levels of Fe, Ni, and Hg were similar between healthy and patient subjects (p > 0.05). In patients with high or low thyroid activity, strong mutual correlations between Cr, Ni, and Fe were noticeable (p < 0.05). In hypothyroid patients, no significant correlation between Zn and Hg, Co, and Cd was found, but Zn was moderately and positively correlated with other trace metals. The moderate negative correlations between Cd-Cr (p = - 0.46) and Cd-Fe (p = - 0.43) were also observed. Logistic regression analysis showed that the effect of Cr, Co, Pb, Cu, Zn, and Cd was significant in developing hyperthyroidism and hypothyroidism; whereas, in patients with thyroid cancer, the effect of Cr, Cd, and Pb was found to be significant. In conclusion, our findings suggest that toxic metals such as Pb, Cd, and Cr can increase the risk of developing hypothyroidism and thyroid cancer, but more research is needed to evaluate the potential toxicity mechanisms of Pb, Cd, and Cr.

Evaluation of trace metals in thyroid tissues: Comparative analysis with benign and malignant thyroid diseases

Evaluation of trace metals at level of solid tissue can provide better information than blood or urine and, therefore, could highlight the role of metals in the etiology of organ-specific disease. The current study aimed to establish the baseline content of four essential (Mn, Cu, Zn, Se) and four toxic metals (As, Cd, Pb, U) in the healthy thyroid tissues (HTTs) by considering sex, age and smoking habits. A further aim was to examine whether differences in the content of metals exist in regard to the thyroid diseases, such as benign tumor (BT), Hashimoto's thyroiditis (HT), multinodular goiter (MNG) and thyroid cancer (TC). A total number of investigated tissue samples were 423. All metals were quantified by inductively coupled plasma-mass spectrometry (ICP-MS). It was found that the content of Cu and U was higher in HTTs of women, while the content of Zn was higher in HTTs of men. Increased content of Zn and decreased content of U was found in the group of HTTs above 50 years compared to a younger group (<50 years). Increased content of Cd, Pb and U distinguish smokers from the non-smokers. In comparison with other population groups worldwide, investigated Serbian population had up to 15 times reduced content of Se. Despite the difference in metal's profile according to biological variables, this study also demonstrated, for the first time, that each thyroid disease has its unique metal's profile. The most altered metal's content was found in tissues with HT. Contrarily, the greatest similarity in metal's content with HTTs was found in BT tissues. Based on the increased content, metal's that dominantly discriminated HTTs from the HT, MNG and TC was As, Pb and Cd, respectively. Reported results could highlight the role of toxic and essential trace metals in the not very well clarified etiology of thyroid diseases and, moreover, could provide a molecular basis for pathophysiological changes of metal's hazardous effects on thyroid health at the tissue level.

Biomonitorization of metal ions in the serum of Iranian patients treated with fixed orthodontic appliances in comparison with controls in eastern Iran

The present study aimed to assess the level of metal ions [chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), and zinc (Zn)] in the serum of patients with fixed orthodontic appliances. One hundred samples (32 males, 68 females) were collected from patients undergoing fixed orthodontic treatment for different periods. A reference (control) group (24 males, 16 females) who had no appliances was used to properly evaluate the changes in the level of these elements in orthodontic appliance users. The element concentrations were measured using inductively coupled plasma mass spectrometry (ICP-MS). Higher concentrations of metal ions (except for Cr) were found in the serum of the orthodontic group. Bivariate scatter plot showed a highly significant (p < 0.001) correlation between Ni and other elements. The duration of orthodontic treatment increased significantly the Ni levels whereas the bracket type was found to have no significant impact on altering the concentration level of metal ions. The results of the SEM-EDS showed a high variation in the level of metal ions in the brackets and wires. In conclusion, fixed orthodontic appliances increased serum levels of Ni, Zn, Mn, Fe, and Cu but did not change Cr levels.

Discrete sampling based-flow injection as an introduction system in ICP-MS for the direct analysis of low volume human serum samples

Discrete sampling based on the flow injection options offered by advanced autosamplers has been tested and applied for the direct analysis of low volume samples (human serum) for multi-elemental purposes (simultaneous Al, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Ni, Pb, Rb, Se, V, and Zn assessment). Serum samples (200 µL aliquots) were directly diluted to 2.0 mL with 1% (v/v) HNO₃, and discrete sampling operating conditions were optimized to allow cleaning, loading (300 µL injection loop), and measuring steps by using a volume lower than 2.0 mL (diluted serum sample). Matrix effect has been overcome by using the standard addition technique, and accurate results implied the use of kinetic energy discrimination (KED) mode (He as a collision gas) for measurements. The proposed method has been found to be reliable for serum samples analysis because of the low sample volume requirements, the minimal sample preparation required, and high sampling rate (each replicate analysis takes 2.50 min). In addition, validation results show good precision and accuracy (both analytical recovery and analysis of certified reference materials), and acceptable sensitivity. Applicability of the proposed method has been finally demonstrated by analysing several serum samples from healthy adults.