Diagnosis and management of thyroid disorders and thyroid hormone supplementation in adult horses and foals.

Equine thyroid disorders pose a diagnostic challenge in clinical practice because of the effects of nonthyroidal factors on the hypothalamic-pituitary-thyroid axis, and the horse's ability to tolerate wide fluctuations in thyroid hormone concentrations and survive without a thyroid gland. While benign thyroid tumours are common in older horses, other disorders like primary hypothyroidism or hyperthyroidism in adult horses and congenital hypothyroidism in foals are rare. There is a common misunderstanding regarding hypothyroidism in adult horses, especially when associated with the clinical profile of obesity, lethargy, and poor performance observed in dogs and humans. Low blood thyroid hormone concentrations are often detected in horses as a secondary response to metabolic and disease states, including with the nonthyroidal illness syndrome; however, it is important to note that low thyroid hormone concentrations in these cases do not necessarily indicate hypothyroidism. Assessing equine thyroid function involves measuring thyroid hormone concentrations, including total and free fractions of thyroxine (T4) and triiodothyronine (T3); however, interpreting these results can be challenging due to the pulsatile secretion of thyroid hormones and the many factors that can affect their concentrations. Dynamic testing, such as the thyrotropin-releasing hormone stimulation test, can help assess the thyroid gland response to stimulation. Although true hypothyroidism is extremely rare, thyroid hormone supplementation is commonly used in equine practice to help manage obesity and poor performance. This review focuses on thyroid gland pathophysiology in adult horses and foals, interpretation of blood thyroid hormone concentrations, and evaluation of horses with thyroid disorders. It also discusses the use of T4 supplementation in equine practice.

The Effects of Zinc and Selenium Co-Supplementation on Resting Metabolic Rate, Thyroid Function, Physical Fitness, and Functional Capacity in Overweight and Obese People under a Hypocaloric Diet: A Randomized, Double-Blind, and Placebo-Controlled Trial.

Evidence of the effectiveness of zinc (Zn) and selenium (Se) on resting metabolic rate (RMR) and physical function parameters in people with overweight and obesity is scarce, while the effects of zinc and selenium on thyroid function and body composition are still a topic of debate and controversy. The aim of this randomized, double-blind, and placebo-controlled trial was to examine the effects of a hypocaloric diet and Se-Zn co-supplementation on RMR, thyroid function, body composition, physical fitness, and functional capacity in overweight or obese individuals. Twenty-eight overweight-obese participants (mean BMI: 29.4 ± 4.7) were randomly allocated (1:1) to the supplementation group (n = 14, 31.1 ± 5.5 yrs, 9 females) and the placebo group (n = 14, 32.1 ± 4.8 yrs, 6 females). The participants received Zn (25 mg of zinc gluconate/day) and Se (200 mcg of L-selenomethionine/day) or placebo tablets containing starch for eight weeks. The participants of both groups followed a hypocaloric diet during the intervention. RMR, thyroid function, body composition, cardiorespiratory fitness (VO2max), and functional capacity (sit-to-stand tests, timed up-and-go test, and handgrip strength) were assessed before and after the intervention. A significant interaction was found between supplementation and time on RMR (p = 0.045), with the intervention group's RMR increasing from 1923 ± 440 to 2364 ± 410 kcal/day. On the other hand, no interaction between supplementation and time on the thyroid function was found (p > 0.05). Regarding the effects of Zn/Se co-administration on Se levels, a significant interaction between supplementation and time on Se levels was detected (p = 0.004). Specifically, the intervention group's Se serum levels were increased from 83.04 ± 13.59 to 119.40 ± 23.93 µg/L. However, Zn serum levels did not change over time (90.61 ± 23.23 to 89.58 ± 10.61 umol/L). Even though all body composition outcomes improved in the intervention group more than placebo at the second measurement, no supplement × time interaction was detected on body composition (p > 0.05). Cardiorespiratory fitness did not change over the intervention. Yet, a main effect of time was found for some functional capacity tests, with both groups improving similarly over the eight-week intervention period (p < 0.05). In contrast, a supplement x group interaction was found in the performance of the timed up-and-go test (TUG) (p = 0.010), with the supplementation group improving more. In conclusion, an eight-week intervention with Zn/Se co-supplementation combined with a hypocaloric diet increased the RMR, TUG performance, and Se levels in overweight and obese people. However, thyroid function, Zn levels, body composition, and the remaining outcomes of exercise performance remained unchanged.

Association between serum-free thyroxine level and all-cause mortality in critically ill patients: a retrospective study from MIMIC-IV.

Background: Low thyroxine (T4) levels have been observed in critically ill patients; however, controversial results regarding T4 supplemental therapy are reported. The association between serum free T4 (FT4) levels and mortality in critically ill patients has not been fully established and needs to be clarified. Methods: Data from the Medical Information Mart for Intensive Care (MIMIC)-IV were collected and analyzed. The association between FT4 level and 30-day mortality after ICU admission was analyzed using Kaplan-Meier curves, spline smoothing fitting, martingale residuals of the null Cox model, and restricted cubic spline (RCS). Logistic regression, Cox regression, and receiver operating characteristic curve (ROC) were used to uncover the relationship and predictive value of serum FT4 and 30-day mortality in critically ill patients. Results: In the final analysis, 888 patients were enrolled, and the serum FT4 levels were divided into four groups. A significant difference in 30-day mortality was observed between the four groups. Kaplan-Meier curves also presented significantly higher 30-day mortality in groups 1 and 2 (p < 0.0001). Further multivariance logistic regression showed that group 1 with FT4 levels lower than 0.7 µg/dl can predict 30-day mortality (odds ratio (OR) = 3.30, 95% confidence interval (CI) = 1.04-11.31). Spline smoothing fitting analysis showed a "V"-shaped line between 30-day mortality and FT4 level within 0-3 µg/dl. Further RCS analysis showed that the risk of death decreased rapidly as FT4 levels increased when serum FT4 levels were lower than 1.2 µg/dl and started to become flat afterward. The area under the ROC of the lower FT4 level to predict 30-day mortality was 0.833 (95% CI = 0.788-0.878). Both multivariant Cox regression and logistic regression showed that FT4 levels lower than 1.2 µg/dl can independently predict 30-day mortality when adjusted for other potential confounders (HR = 0.34, 95% CI = 0.14-0.82; OR = 0.21, 95% CI = 0.06-0.79, respectively), but its predictive power disappeared when adjusted for T3 or total T4. Conclusion: Serum FT4 levels were significantly negatively associated with 30-day mortality when they were lower than 1.2 µg/dl and could predict the risk of 30-day mortality. A higher FT4 level is potentially related to increased 30-day mortality.

Effects of Triiodothyronine Treatment in an Animal Model of Heart Failure with Preserved Ejection Fraction.

Background: Low levels of triiodothyronine (T3) are common in patients with heart failure (HF). Our aim was to evaluate the effects of supplementation with low and replacement doses of T3 in an animal model of HF with preserved ejection fraction (HFpEF). Methods: We evaluated four groups: ZSF1 Lean (n = 8, Lean-Ctrl), ZSF1 Obese (rat model of metabolic-induced HFpEF, n = 13, HFpEF), ZSF1 Obese treated with a replacement dose of T3 (n = 8, HFpEF-T3high), and ZSF1 Obese treated with a low-dose of T3 (n = 8, HFpEF-T3low). T3 was administered in drinking water from weeks 13 to 24. The animals underwent anthropometric and metabolic assessments, echocardiography, and peak effort testing with maximum O2 consumption (VO2max) determination at 22 weeks, and a terminal hemodynamic evaluation at 24 weeks. Afterwhile myocardial samples were collected for single cardiomyocyte evaluation and molecular studies. Results: HFpEF animals showed lower serum and myocardial thyroid hormone levels than Lean-Ctrl. Treatment with T3 did not normalize serum T3 levels, but increased myocardial T3 levels to normal levels in the HFpEF-T3high group. Body weight was significantly decreased in both the T3-treated groups, comparing with HFpEF. An improvement in glucose metabolism was observed only in HFpEF-T3high. Both the treated groups had improved diastolic and systolic function in vivo, as well as improved Ca2+ transients and sarcomere shortening and relaxation in vitro. Comparing with HFpEF animals, HFpEF-T3high had increased heart rate and a higher rate of premature ventricular contractions. Animals treated with T3 had higher myocardial expression of calcium transporter ryanodine receptor 2 (RYR2) and α-myosin heavy chain (MHC), with a lower expression of ß-MHC. VO2max was not influenced by treatment with T3. Myocardial fibrosis was reduced in both the treated groups. Three animals died in the HFpEF-T3high group. Conclusions: Treatment with T3 was shown to improve metabolic profile, myocardial calcium handling, and cardiac function. While the low dose was well-tolerated and safe, the replacement dose was associated with increased heart rate, and increased risk of arrhythmias and sudden death. Modulation of thyroid hormones may be a potential therapeutic target in HFpEF; however, it is important to take into account the narrow therapeutic window of T3 in this condition.

Prenatal thyroid hormones accelerate postnatal growth and telomere shortening in wild great tits.

The early-life environment is known to affect later-life health and disease, which could be mediated by the early-life programming of telomere length, a key hallmark of ageing. According to the fetal programming of telomere biology hypothesis, variation in prenatal exposure to hormones is likely to influence telomere length. Yet, the contribution of key metabolic hormones, i.e. thyroid hormones (THs), has been largely ignored. We recently showed that in contrast to predictions, exposure to elevated prenatal THs increased postnatal telomere length in wild collared flycatchers, but the generality of such effect, the underlying proximate mechanisms and consequences for survival have not been investigated. We therefore conducted a comprehensive study evaluating the impact of THs on potential drivers of telomere dynamics (growth, post-natal THs, mitochondria and oxidative stress), telomere length and medium-term survival using wild great tits as a model system. While prenatal THs did not significantly affect telomere length a week after hatching (i.e. day 7), they influenced postnatal telomere shortening (i.e. shorter telomeres at day 14 and the following winter) but not apparent survival. Circulating THs, mitochondrial density or oxidative stress biomarkers were not significantly influenced, whereas the TH-supplemented group showed accelerated growth, which may explain the observed delayed effect on telomeres. We discuss several alternative hypotheses that may explain the contrast with our previous findings in flycatchers. Given that shorter telomeres in early life tend to be carried until adulthood and are often associated with decreased survival prospects, the effects of prenatal THs on telomeres may have long-lasting effects on senescence.

Triiodothyronine Supplementation in Infants Undergoing Cardiopulmonary Bypass: A Randomized Controlled Trial.

Cardiopulmonary bypass (CPB) profoundly suppresses circulating thyroid hormone levels in infants. We performed a multicenter randomized placebo controlled trial to determine if triiodothyronine (T3) supplementation improves reduces time to extubation (TTE) in infants after CPB. Infants (n = 220) undergoing cardiac surgery with CPB and stratified into 2 age cohorts: ≤30 days and >30 days to <152 days were randomization to receive either intravenous triiodothyronine or placebo bolus followed by study drug infusion until extubated or at 48 hours, whichever preceded. T3 did not significantly alter the primary endpoint, TTE (hazard ratio for chance of extubation (1.08, 95% CI: 0.82-1.43, P = 0.575) in the entire randomized population with censoring at 21 days. T3 showed no significant effect on TTE (HR 0.82, 95% CI:0.55-1.23, P = 0.341) in the younger subgroup or in the older (HR 1.38, 95% CI:0.95-2.2, P = 0.095). T3 also did not significantly impact TTE during the first 48 hours while T3 levels were maintained (HR 1.371, 95% CI:0.942-1.95, P = 0.099) No significant differences occurred for arrhythmias or other sentinel adverse events in the entire cohort or in the subgroups. This trial showed no significant benefit on TTE in the entire cohort. T3 supplementation appears safe as it did not cause an increase in adverse events. The study implementation and analysis were complicated by marked variability in surgical risk, although risk categories were balanced between treatment groups.

Can Mild-to-Moderate Iodine Deficiency during Pregnancy Alter Thyroid Function? Lessons from a Mother-Newborn Cohort.

Severe iodine deficiency during pregnancy has substantial hormonal consequences, such as fetal brain damage. Data on the potential effects of mild-to-moderate iodine deficiency on the thyroid function of pregnant women and their newborns are scarce and divergent. We investigated the association between iodine intake in pregnancy and maternal and neonatal thyroid function in a region with mild-to-moderate iodine deficiency. Pregnant women's iodine status was evaluated using an iodine food frequency questionnaire, serum thyroglobulin (Tg), and urinary iodine concentration (UIC). Neonatal thyrotropin (nTSH) values were measured after birth. Obstetrics and anthropometric data were also collected. Among the 178 women (median age 31 years) included in the study, median (interquartile range) estimated dietary iodine intake, Tg and UIC were 179 (94−268) µg/day, 18 (11−33) µg/L, and 60 (41−95) µg/L, respectively. There was a significant inverse association of iodine intake with Tg values among the study population (ß = −0.2, F = 7.5, p < 0.01). Women with high free triiodothyronine (FT3) values were more likely to exhibit an estimated iodine intake below the estimated average requirement (160 µg/day, odds ratio [OR] = 2.6; 95% confidence interval [CI], 1.1−6.4; p = 0.04) and less likely to consume iodine-containing supplements (OR = 0.3, 95% CI, 0.1−0.8; p = 0.01). It is possible that thyroid function may be affected by iodine insufficiency during pregnancy in regions with mild-to-moderate iodine deficiency. The relatively small sample size of the studied population warrants further investigation.

Effects of dietary triiodothyronine or dopamine on small intestinal oxygen consumption in chicks.

This study aimed to investigate the effects of triiodothyronine (T3)- or dopamine (Dp)-supplemented diets on oxygen consumption by Na+, K+-ATPase activity in broiler chicks. Five groups, each with twenty-four 6-day-old chicks, randomly received one of the five dietary treatments: (1) Basal diet (commercial broiler rations with 23.0% crude protein and 3,133 kcal metabolizable energy/kg) or CON, (2) basal diet plus 0.7 µmol Dp/kg diet or Dp0.7, (3) basal diet plus 2.4 µmol Dp/kg diet or Dp2.4, (4) basal diet plus 1.9 µmol T3/kg diet or T1.9, and (5) basal diet plus 3.8 µmol T3/kg diet or T3.8 from 6 to 14 days of age. There were four replicates per treatment and 120 birds in total. At 14 days of age, three chicks from each replicate of each treatment were pooled into a flock and fed commercial broiler diets until 7 weeks of age. Compared to CON group, birds fed with T3-supplemented diets had lower thyroid, abdominal fat pad, gizzard and pancreas weight, and heavier heart weight adjusted for fasted body weight. Chicks with T1.9 had lower ileal densities at 14 day old compared with those in Dp groups or CON. Chicks with T3.8 exhibited greater duodenal and jejunal O2 consumptions as well as ouabain-sensitive O2 consumptions of jejunum and small intestine (duodenum, jejunum, and ileum) by 46.5%, 58.3%, 40.6%, and 26.4% increases, than those in CON. Partial correlation analysis revealed that the weight and length of the small intestine were negatively correlated with body weight gain. Oxygen consumption in the various small intestinal segments was negatively correlated with their respective densities (mg/mm2). In conclusion, a greater oxygen requirement for maintaining ouabain-sensitive respiration (Na+-K+-ATPase) in the intestine limits energy availability to support gastrointestinal tract growth and, thereby, may result in lower body weight gain.

Assessment of Joint Impact of Iodine, Selenium, and Zinc Status on Women's Third-Trimester Plasma Thyroid Hormone Concentrations.

BACKGROUND: Iodine is essential for synthesizing thyroid hormones, but other micronutrients are also required for optimal thyroid function. However, there is a lack of data on combined micronutrient status in relation to thyroid hormones in pregnancy. OBJECTIVES: We aimed to assess the joint associations of iodine, selenium, and zinc status with plasma concentrations of thyroid hormones and thyroid-stimulating hormone (TSH) in pregnancy. METHODS: We included 531 pregnant women (aged 22-40 y) participating in a Swedish birth cohort who provided blood and spot urine samples in gestational weeks 27-33 (mean: 29). Associations of urinary iodine concentration (UIC), plasma selenium concentration, and plasma zinc concentration (measured by inductively coupled plasma mass spectrometry) with plasma hormone concentrations [total and free thyroxine (tT4, fT4), total and free triiodothyronine (tT3, fT3), and TSH] were explored with Bayesian kernel machine regression (BKMR; n = 516; outliers excluded) and multivariable-adjusted linear regression (n = 531; splined for nonlinear associations). RESULTS: Median (IQR) micronutrient concentrations were 112 µg/L (80-156 µg/L) for UIC, 67 µg/L (58-76 µg/L) for plasma selenium, and 973 µg/L (842-1127 µg/L) for plasma zinc; the former 2 median values were below recommended concentrations (150 µg/L and 70 µg/L, respectively). Mean ± SD TSH concentration was 1.7 ± 0.87 mIU/L, with 98% < 4 mIU/L. BKMR showed a positive trend of joint micronutrient concentrations in relation to TSH. Plasma zinc was most influential for all hormones but tT3, for which plasma selenium was most influential. In adjusted linear regression models, zinc was positively associated with tT4, tT3, and TSH, and <1200 µg/L also with fT4 and fT3. Selenium was inversely associated with fT3, and <85 µg/L with tT3. CONCLUSIONS: Pregnant women's plasma TSH concentrations in the early third trimester increased with increasing joint status of iodine, selenium, and zinc. Zinc and selenium were more influential than iodine for the hormone concentrations. Multiple micronutrients need consideration in future studies of thyroid hormone status.

Quality of life comparison in thyroxine hormone withdrawal versus triiodothyronine supplementation prior to radioiodine ablation in differentiated thyroid carcinoma: a prospective cohort study in the Indian population.

BACKGROUND: Thyroid withdrawal in preparation for radioiodine ablation (RIA) may have a profound impact on health-related quality of life (HRQL). Cost implications and scheduling limit the use of recombinant TSH and triiodothyronine (T3) with its shorter half-life is a conceptually attractive alternative. METHODS: Prospective cohort study design with patients having withdrawal of thyroxine (n = 37) or T3 supplementation (n = 33). HRQL was assessed using EORTC QLQ-C30, QLQ-H&N35 and modified Billewicz questionnaires. Time interval to achieve optimal TSH levels (at least 30 mIU/ml) prior to RIA was determined. RESULTS: With the exception of emotional domain (QLQ-C30 p = 0.045), LT3 supplementation did not confer significant benefit when compared to LT4 withdrawal. Target serum TSH levels was achieved in 95% of patients by week 4 post thyroidectomy. CONCLUSIONS: LT3 supplementation delivered equivocal benefit and therefore the alternate strategies to minimize the impact on HRQL of reduction in the duration of hypothyroidism in T4 withdrawal are suggested.

Associations between pituitary-thyroid hormones and depressive symptoms in individuals with anorexia nervosa before and after weight-recovery.

BACKGROUND: There is sound evidence that the hypothalamic-pituitary-thyroid axis plays a role in mood regulation. Alterations in this axis, particularly low triiodothyronine syndrome, are a common neuroendocrine adaptation to semi-starvation in patients with anorexia nervosa (AN), who also frequently suffer from co-existing depressive symptoms. We therefore aimed to investigate the associations between pituitary-thyroid function and psychopathology, in particular depressive symptoms, at different stages of AN using a combined cross-sectional and longitudinal study design. METHODS: Pituitary-thyroid status (FT3, free triiodothyronine; FT4, free thyroxine; conversion ratio FT3/FT4; TSH, thyroid-stimulating hormone) was assessed in 77 young acutely underweight females with AN (acAN) and in 55 long-term weight-recovered individuals with former AN (recAN) in a cross-sectional comparison to 122 healthy controls (HC). Further, pituitary-thyroid status of 48 acAN was reassessed after short-term weight-restoration. We performed correlation analyses of pituitary-thyroid parameters with self-reported measures of psychopathology. RESULTS: AcAN showed significantly lower FT3, FT4, FT3/FT4 ratio, and TSH levels compared to HC. Pituitary-thyroid alterations were partly reversed after short-term weight-restoration. RecAN still had lower FT3 concentrations than HC. Lower FT3 concentrations and FT3/FT4 ratios were associated with more severe depressive symptoms in acAN, occurring prominently in cases of manifest low triiodothyronine syndrome. Longitudinally increasing FT3/FT4 ratios (change scores) were inversely correlated with depressive and general psychiatric symptoms after short-term weight-restoration. CONCLUSIONS: Our results suggest a potential modulation of the severity of depressive symptoms by temporarily decreased FT3 concentrations and inhibited thyroid hormone conversion (FT3/FT4 ratios) in acutely underweight AN. Associations between conversion ratios FT3/FT4 and psychopathology seem to persist across short-term weight-restoration. The findings of our study might have relevant clinical implications, ranging from thyroid monitoring to experimental low-dose thyroid hormone supplementation in certain patients with AN showing severe psychiatric impairment and overt thyroid hormone alterations.

Thyroid hormones in relation to toxic metal exposure in pregnancy, and potential interactions with iodine and selenium.

BACKGROUND: Several endocrine-disrupting metals may affect thyroid function, but the few available studies of exposure during pregnancy and thyroid hormones are inconclusive. OBJECTIVE: To explore if environmental exposure to cadmium (Cd), lead (Pb), and methylmercury (MeHg) impacts thyroid function in pregnancy, and interacts with iodine and selenium status. METHODS: Women in a Swedish birth cohort provided blood and urine samples in early third trimester. Concentrations of erythrocyte Cd, Pb, and Hg (n = 544), urinary Cd and iodine (n = 542) and plasma selenium (n = 548) were measured using inductively coupled plasma-mass spectrometry.Free and total thyroxine (fT4, tT4) and triiodothyronine (fT3, tT3), and thyroid stimulating hormone (TSH), were measured in plasma (n = 548) with electrochemiluminescence immunoassays. Metal-hormone associations were assessed in regression models, and metal mixture effects and metal-nutrient interactions were explored in Bayesian kernel machine regression (BKMR). RESULTS: In multivariable-adjusted regression models, a doubling of urinary Cd was associated with a mean increase in tT4 of 2.7 nmol/L (95% CI: 0.78, 4.6), and in fT3 and tT3 of 0.06 pmol/L (0.02, 0.10) and 0.09 nmol/L (0.05, 0.13), respectively. A doubling of urinary Cd was associated with a -0.002 (-0.003, -0.001) and -0.03 (-0.05, -0.02) decrease in the fT4:tT4 and fT3:tT3 ratio, respectively. A doubling of erythrocyte Hg (>1 µg/kg) was associated with a decrease in fT3 and tT3 by -0.11 pmol/L (-0.16, -0.05) and -0.11 nmol/L (-0.16, -0.06), respectively, and a -0.013 (-0.02, -0.01) decrease in the fT3:fT4 ratio. BKMR did not indicate any mixture effect of toxic metals or interactions between metals and iodine or selenium in relation to the hormones. CONCLUSION: Our findings suggest that exposure to Cd and Hg, at levels globally prevalent through the diet, may affect thyroid function during pregnancy, independently of iodine and selenium levels. Further studies on potential implications for maternal and child health are warranted.

The effects of the mixture of betaine, vitamin C, St John's wort (Hypericum perforatum L.), lavender, and Melissa officinalis on performance and some physiological parameters in broiler chickens exposed to heat stress.

The unprecedented rate of global warming requires more immaculate strategies to fight the heat stress and its detrimental effects on poultry sector. Nutritional strategies, particularly herbal extracts, play a crucial importance in this scenario. Therefore, this study was conducted to evaluate the effects of a novel selected mixture (hereafter refers to as Stress-Bio-Max, SBM) comprising St John's wort, lavender, Melissa officinalis extracts, betaine, and Vit C on heat-stressed broilers. A total of 300 male broiler chicks were allocated to 4 treatments: T1, Control (no SBM in drinking water); T2, 0.25 mL/L of SBM in drinking water; T3, 0.5 and T4, 1 mL/L of SBM, which applied since d 32. The birds underwent heat stress (40 ± 1) daily from d 35 to 42 of the experiment (2 pm-8 pm). The results show the superior weight gain of T2 and T3 from d 7 to 42 compared to other groups, 72.5 and 72.7 g/d, respectively (P < 0.05). Corticosterone level was higher on d 35 in T1 (4.674 ng/mL, P < 0.05) and lower in T2 and T3 (2.64 and 2.952 ng/mL, respectively, P < 0.05); T2 and T3 also caused the lowest concentrations of corticosterone on d 40 (5.198 and 6.458 ng/mL, respectively, P < 0.05). The superior triiodothyronine levels belonged to T2 (0.935 ng/mL, P < 0.05) on d 35 and T2 and T3 on d 40 (0.699 and 0.582 ng/mL, respectively, P < 0.05). T2, T3, and T4 caused a rise in glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities (P < 0.05). A significant higher amount of total antioxidant capacity (TAC) belonged to the groups treating with SBM (P < 0.05). The SBM in T2 and T3 resulted in the lowest levels of malondialdehyde (MDA), aspartate transaminase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). Results from this study indicate that SBM may alleviate the negative impacts associated with heat stress in broiler chickens.

Triiodothyronine ameliorates silica-induced pulmonary inflammation and fibrosis in mice.

Environmental exposure to silica or particles is very common in natural, agricultural and industrial activities. Chronic silica exposure can lead to silicosis, which remains one of the most serious interstitial lung diseases all through the world, while viable therapeutic choices are restricted. Triiodothyronine (T3) has been shown to exert a defensive role in many pulmonary diseases, however, rare data are available regarding the role of T3 on silica-induced injury. We constructed an experimental silicosis mouse model and T3 was intraperitoneally administrated after instillation of silica to observe the effect of T3 on silica-induced lung inflammation and fibrosis. Our results showed that the silicosis mouse model was accompanied by changes in thyroid morphology and function, and T3 supplement reduced silica-induced lung damage, inflammation and collagen deposition. The protective properties of T3 on silica-induced lung injury could be partially mediated through thyroid hormone receptors. And the mechanism by which T3 treatment ameliorated silica-induced fibrosis appeared to be via the reduction of glycolysis. Also, T3 could sufficiently postpone the progression of pulmonary fibrosis in established silicosis. Our findings reveal that administration of T3 could down-regulate the inflammatory response, pulmonary fibrosis and other lung damage caused by silica. The reduction of glycolysis may be one of the mechanisms.

Effects of Medicinal Plants and Organic Selenium against Ovine Haemonchosis.

The objective of this study was to determine the effect of traditional medicinal plants typical to Central Europe as well as organic selenium on increasing the resistance of lambs to gastrointestinal nematode (GIN) infection with Haemonchus contortus. 21 female lambs were infected with third-stage larvae of H. contortus on the day (D) 0 and re-infected on D49 and D77. The animals were divided into three groups based on a treatment diet: a basal diet (control), a diet enriched with dry plants (Herbmix), and a diet enriched with selenized yeast (Selplex). The number of eggs per gram (EPG) of feces was quantified on D21, D28, D35, D42, D49, D56, D63, D70, D77, D84, D91, D98, D105, D112, and D119. The mean reductions in EPG on D28 were 43.4 and 28.6% for Selplex and Herbmix, respectively. The reduction in egg output was nearly uniform throughout the experiment for Selplex. However, for Herbmix the mean reduction was only 19.8% up to D91 and 46.1% after D91. Glutathione peroxidase activity in the blood from D35 to D98 was two to three-fold higher for Selplex than the other groups. Both supplements slowed the dynamics of GIN infection and gradually increased the resistance of lambs against ovine haemonchosis.

Serum concentration of thyroxine and triiodothyronine in newborn calves from cows supplemented with barium selenate / Concentración sérica de tiroxina y triiodotironina en terneros recién nacidos de madres suplementadas con selenato de bario / Concentração de tiroxina e triiodotironina sérica em bezerros recém-nascidos de mães suplementadas com selenato de bário

Abstract Background: Barium selenate is an inorganic source of selenium (Se) used in prolonged-release preparations to treat selenium deficiency in bovines. Objective: To evaluate serum concentrations of triiodothyronine (T3) and thyroxine (T4) hormones in newborn calves from mothers supplemented with barium selenate during prepartum. Methods: Six black Frisian pregnant cows were supplemented with barium selenate subcutaneously during the last two months of gestation, until calving. Six cows were used as controls. All cows were subjected to a low Se diet, consisting of hay from natural pasture and commercial concentrate lacking Se. The Se balance was measured through the activity of erythrocyte glutathione peroxidase (GPx). Serum concentration of T3 and T4 in calves was determined by electrochemiluminescence. Results: Se supplementation during prepartum increased GPx activity in cows from day 45 post-supplementation (p<0.05). Calves from supplemented mothers showed higher average serum Se concentration than calves from non-supplemented mothers. The average concentration of T3 in the calves from supplemented mothers was lower in the first hour of life (p<0.05) compared with calves from mothers of the non-supplemented group. A decrease (p<0.05) in T4 serum concentrations was observed in both groups at seven days of age. Conclusions: Administration of barium selenate to cows during prepartum generates a reduction in serum concentration of T3 in the first hour of life of calves.

Resumen Antecedentes: El selenato de bario es una fuente inorgánica de selenio (Se) utilizada en preparaciones de liberación prolongada para corregir el estado de carencia de Se en bovinos. Objetivo: Evaluar las concentraciones séricas de triyodotironina (T3) y tiroxina (T4) en terneros recién nacidos de madres suplementadas durante el preparto con selenato de bario. Métodos: Seis vacas frisón negro con 7 meses de gestación fueron suplementadas vía subcutánea con selenato de bario dos meses previos a la fecha de parto. Otras seis vacas permanecieron como controles. Todas las vacas se mantuvieron con una dieta cuyo aporte de Se fue inferior a los requerimientos y consistió en heno de pradera natural y concentrado comercial sin Se. El balance de Se se midió usando la actividad eritrocitaria de glutatión peroxidasa (GPx) y las concentraciones de T3 y T4 en terneros mediante electroquimioluminiscencia. Resultados: La suplementación con Se aumentó la actividad de GPx en vacas desde el día 45 post suplementación (p<0,05). Los terneros de madres suplementadas mostraron una concentración sérica promedio de Se mayor que los terneros de madres no suplementadas. La concentración promedio de T3 de terneros de madres suplementadas fue menor en la primera hora de vida (p<0,05) que en terneros de madres no suplementadas. A los 7 días de edad hubo una disminución (p<0,05) en las concentraciones séricas de T4 en ambos grupos. Conclusión: La administración de selenato de bario en vacas preparto genera una disminución en la concentración sérica de T3 en la primera hora de vida del ternero.

Resumo Antecedentes: O selenato de bário é uma fonte inorgânica de selênio (Se) usada em preparações de liberação prolongada para corrigir o status de deficiência de Se em bovinos. Objetivo: Avaliar as concentrações séricas de triiodotironina (T3) e tiroxina (T4) em bezerros recém-nascidos de mães suplementadas durante o pré-parto com selenato de bário. Métodos: Seis vacas friesianas negras aos 7 meses de gestação foram suplementadas com selenato de bário por via subcutânea dois meses antes do parto. Seis outras vacas permaneceram como controle. Todas as vacas foram mantidas em uma dieta cuja contribuição de Se foi inferior aos requeridos e consistiram em feno natural da pradaria e concentrado comercial sem Se. O balanço de Se foi medido usando a atividade eritrocitária das concentrações de glutationa peroxidase (GPx) e T3 e T4 em bezerros por eletroquimiluminescência. Resultados: A suplementação com atividade de GPx aumentou em vacas a partir do dia 45 após a suplementação (p<0,05). Os bezerros de mães suplementadas apresentaram uma concentração sérica média de Se maior que os bezerros de mães não suplementadas. A concentração média de T3 dos bezerros das mães suplementadas foi menor na primeira hora de vida (p<0,05) do que nos bezerros das mães não suplementadas. Aos 7 dias de idade houve uma diminuição (p<0,05) nas concentrações séricas de T4 nos dois grupos. Conclusão: A administração de selenato de bário em vacas de parto gera uma diminuição na concentração sérica de T3 na primeira hora de vida do bezerro.

Thyroid-Modulating Activities of Olive and Its Polyphenols: A Systematic Review.

Olive oil, which is commonly used in the Mediterranean diet, is known for its health benefits related to the reduction of the risks of cancer, coronary heart disease, hypertension, and neurodegenerative disease. These unique properties are attributed to the phytochemicals with potent antioxidant activities in olive oil. Olive leaf also harbours similar bioactive compounds. Several studies have reported the effects of olive phenolics, olive oil, and leaf extract in the modulation of thyroid activities. A systematic review of the literature was conducted to identify relevant studies on the effects of olive derivatives on thyroid function. A comprehensive search was conducted in October 2020 using the PubMed, Scopus, and Web of Science databases. Cellular, animal, and human studies reporting the effects of olive derivatives, including olive phenolics, olive oil, and leaf extracts on thyroid function were considered. The literature search found 445 articles on this topic, but only nine articles were included based on the inclusion and exclusion criteria. All included articles were animal studies involving the administration of olive oil, olive leaf extract, or olive pomace residues orally. These olive derivatives were consistently demonstrated to have thyroid-stimulating activities in euthyroid or hypothyroid animals, but their mechanisms of action are unknown. Despite the positive results, validation of the beneficial health effects of olive derivatives in the human population is lacking. In conclusion, olive derivatives, especially olive oil and leaf extract, could stimulate thyroid function. Olive pomace residue is not suitable for pharmaceutical or health supplementation purposes. Therapeutic applications of olive oil and leaf extract, especially in individuals with hypothyroidism, require further validation through human studies.

Quantification of biotin in plasma samples by column switching liquid chromatography - tandem mass spectrometry.

Biotin (or Vitamin B7) is a vitamin where deficiency can be caused by inadequate intake. Biotin deficiency is rare, as most people get enough biotin from diet, since many foods contain biotin. In addition to biotin from food, intestinal bacteria can synthesize biotin, which can then be absorbed by the body. Supplementation with biotin has been advocated, mainly due to proposed beneficial effects on skin, nail and hair growth. There is no evidence that high biotin intakes are toxic, but a high intake may interfere with diagnostic assays that use biotin-streptavidin technology. These tests are commonly used to measure plasma concentrations of a wide range of hormones. Erroneous results may lead to misdiagnosis of various endocrine disorders. Supplementation with high-dose biotin has been used experimental for the treatment of diseases (e.g. multiple sclerosis) and high doses are used to obtain effect on nail and hair growth. On this background a demand for tests to determine if there is a risk of obtaining false test results when using biotin-streptavidin based tests have appeared. In this paper we present a method based on column switching liquid chromatography tandem mass spectrometry for the quantification of biotin in plasma and serum and explore the effects of biotin on an immunoassay based on biotin strept(avidin) chemistry.

Selenium status and its relationship with thyroid hormones in obese women.

BACKGROUND AND AIMS: Studies have been conducted with the purpose of elucidating thyroid gland dysfunction in obesity, however the contributing factors for such dysfunction are not yet fully understood. Selenium is notable for its role in thyrocyte protection against oxidative damage and control of thyroid hormone synthesis. In addition, subjects with obesity may exhibit alterations in the selenium homeostasis. Therefore, the present study aimed to examine the selenium status and its relationship with serum thyroid hormone levels in obese women. METHODS: This cross-sectional study included 69 euthyroid women, aged between 18 and 50 years, who were divided in two groups: an obese group (n = 35) and a control group with women of normal weight (n = 34). Selenium intake was assessed by three-day diet records and analyzed using NutWin software version 1.5. Plasma, erythrocyte, and urinary selenium levels were determined using inductively coupled plasma optical emission spectrometry. Testing for thyroid hormones and thyroid autoantibodies was performed based on chemiluminescence. RESULTS: The median dietary selenium content was adequate according to the recommendations, with no statistical difference between groups. Obese women had reduced plasma and erythrocyte selenium levels compared to the control group, although selenium concentration in erythrocytes was adequate within the normal range for both groups. There was no significant difference between the urinary selenium concentrations in the subjects; however, the mineral clearance was higher in the obese group. Free triiodothyronine (fT3) and free thyroxine (fT4) levels were higher in obese women with class II obesity when compared to the control group. There was a negative correlation between plasma selenium and serum fT4 levels. CONCLUSIONS: Obese women showed impairment in selenium homeostasis, however, this fact did not seem to adversely affect thyroid metabolism.

Euthyroid sick syndrome in paediatric and adult patients requiring extracorporeal circulatory support and the role of thyroid hormone supplementation: a review.

Non-thyroid disorders may modify thyroid hormone metabolism, resulting in an 'euthyroid sick syndrome'. Studies determining the association of cardiopulmonary bypass to thyroid function showed changes in line with this euthyroid sick syndrome. In some cases, cardiovascular dysfunction after cardiac surgery with cardiopulmonary bypass is comparable to that noticed in hypothyroidism associated with low cardiac output and elevated systemic vascular resistance. Numerous lines of research have proposed that triiodothyronine can behave acutely as a positive inotropic and vasodilator agent. The aim of this review is to present an update on the current literature about in what clinical situations the use of thyroid supplementation during the perioperative period of extracorporeal circulation in the adult and paediatric populations may impact outcome to any appreciable degree. The contribution of thyroid function in patients undergoing a ventricular assist device implantation is additionally reviewed and future study directions are proposed. This is a narrative review, where the search strategy consisted on retrieving the articles through an extensive literature search performed using electronic databases from January 1978 up to September 2019. All controlled trials randomly allocating to perioperative thyroid hormone administration in children and adults undergoing extracorporeal circulation for cardiac surgery were considered. Thyroid hormone supplementation may be recommended particularly in selected paediatric sub-populations. There is currently no firm evidence regarding the benefits of routine use of thyroid hormone administration in cardiac adult patients. Further studies are required to assess the beneficial effect of thyroid hormone on patients with end-stage heart failure supported by ventricular assist devices.