Thyroxine Concentrations Research Articles

Gestational trimester-specific reference ranges for serum thyrotropin and free thyroxine in Japanese.

Thyroid diseases in pregnant and lactating women may result in adverse outcomes for both mothers and infants. A reference range for thyroid function is required in different areas; however, few studies on the gestational change or reference ranges of thyrotropin (TSH) and free thyroxine (FT4) concentrations for Japanese pregnant women have been reported. To establish the gestational trimester-specific reference ranges of serum TSH and FT4 concentrations, our previously published data on 481 pregnant women with the mean age of 30.8 years who provided serum samples as early as gestational week (GW) 6 was compiled by using their percentile values. The overall median urinary iodine concentration (UIC) during pregnancy was 201 μg/L suggesting adequate iodine intake. The prevalence of positive serum thyroid autoantibody (ThAb), i.e., antithyroid peroxidase antibody (TPOAb) and antithyroglobulin antibody (TgAb), was 11.4%. The reference ranges (2.5-97.5th percentile) of serum TSH and FT4 concentration calculated for samples with negative TgAb and TPOAb were 0.04-6.06 mIU/L in the first trimester (T1), 0.31-3.11 mIU/L in the second trimester (T2) and 0.48-3.93 mIU/L in the third trimester (T3) for TSH, and 1.10-1.87 ng/dL (T1), 0.76-1.56 ng/dL (T2) and 0.76-1.14 ng/dL (T3) for FT4. Compared to published data around the world in the 2017 American Thyroid Association (ATA) guideline, both the upper and lower limits of our TSH and FT4 reference ranges in the first trimester were higher than those in other countries. Further research is necessary in larger samples.

Association Between Low-normal Range Free Thyroxine Concentration and Increase in Carotid Intima–Media Thickness with Age among Euthyroid Japanese Men

Association Between Low-normal Range Free Thyroxine Concentration and Increase in Carotid Intima–Media Thickness with Age among Euthyroid Japanese Men

Comparison of the Vcheck and IMMULITE 2000 methods for T4 measurement in canine and feline serum

The aim of this study was to compare canine and feline thyroxine (T4) results obtained by the Vcheck method with those obtained by the IMMULITE 2000 immunoassay, which had previously been validated for canine serum. The concentration of T4 in 53 canine and 44 feline serum samples was determined concurrently by the Vcheck and IMMULITE methods, the latter as the reference method. The T4 values were compared using the IMMULITE Youden plot and Deming regression analysis. According to the regression analysis, the two methods gave comparable results. Spearman’s correlation shows a very high consistency of the results obtained by the two analyzers. The results of the Vcheck method were comparable to those of the IMMULITE 2000 reference method, so Vcheck may be used as an alternative assay to evaluate the serum thyroxine concentration in dogs and cats for the diagnosis of thyroid gland disease.

Effect of Levothyroxine Replacement on Cognitive Function Impairment in a Sample of Egyptian Population with Subclinical Hypothyroidism

Introduction: Subclinical hypothyroidism (SHT) is characterized by a normal range of free thyroxin concentrations together with increased serum TSH levels. SHT is defined as serum thyroid-stimulating hormone (TSH) concentration above the upper limit of the reference range in the face of normal free FT4 and FT3 levels. The effect of SHT on cognitive function has been investigated in several preclinical studies, and a growing body of evidence has suggested a relevant link between thyroid hormones and the central nervous system. Objectives: This study aimed to investigate the effect of levothyroxine replacement on cognitive impairment in a sample of Egyptian patients with SHT. Methods: A prospective cohort study conducted on 30 patients with cognitive impairment and SHT attending an endocrine outpatient clinic at the Ain Shams University Hospital to study the effect of levothyroxine supplementation on cognitive impairment in patients with SHT. The study was conducted on 30 patients. All participants were subjected to a full history taking; thorough clinical examination; laboratory investigations including thyroid profile (FT3, FT4, TSH), anti-thyroid peroxidase antibodies, anti-thyroglobulin antibodies, and lipid profile; imaging tests as neck ultrasound, echocardiography, and carotid duplex; and finally Addenbrooke’s questionnaire used to diagnose mild cognitive impairment. Results: A highly statistically significant difference was found before, 3 months and 6 months after treatment with levothyroxine regarding all clinical data, TSH, LDL, T. cholesterol, FT3, FT4 and HDL, carotid intima-media thickness, and Addenbrooke’s questionnaire. Our study showed a statistically significant inverse correlation between TSH level and mild cognitive impairment before and after treatment with levothyroxine at 3 and 6 months intervals as when TSH increased, results of Addenbrooke’s questionnaire decreased and, so, cognitive impairment increased, while when TSH decreased in response to thyroxine replacement, cognitive impairment improved as detected by an increase in the patient’s score. Conclusion: SHT has a great effect on cognitive impairment, as normalization in TSH level results in improvement in cognitive function. Also, there was a significant reduction in carotid intima-media thickness, which may contribute to improvement of cognitive function in addition to a great improvement in lipid profile, which in turn positively affects cardiac and cognitive function.

ДИНАМИКА ГОРМОНАЛЬНОГО СТАТУСА МОЛОДНЯКА СИММЕНТАЛЬСКОЙ ПОРОДЫ В УСЛОВИЯХ РАЗЛИЧНЫХ СИСТЕМ СОДЕРЖАНИЯ

The work is devoted to the study of the dynamics of the hormonal status of young cattle depending on the housing system. In this regard, the functional activity of the endocrine glands was studied: the adrenal cortex, pancreas, thyroid and genital glands. The content of cortisol, insulin, testosterone, thyroxine in the blood serum was determined during the periods: immediately after birth, at the daily age, after reaching 1, 2, 4, 6, 8, 12 and 18 months. It was found that the cortisol content in the blood of newborn calves (148.6–152.7 nmol/l) was the maximum. By the end of the first day, the level of this hormone decreased by an average of 7.07–17.62%. By 18 months, the cortisol content was in the range of 32.3–39.3 nmol/l. The bulls of the control group were more susceptible to the effect of adverse environmental factors. The highest level of thyroxine (169.2–173.4 nmol/l) was at birth. In subsequent periods, the thyroxine content decreased. Activation of the thyroid gland was noted at the age of 8 and 12 months. This is due to the period of puberty. The maximum values of insulin concentration in the blood were noted in daily bulls (1.28–1.83 mmol/l). Thus, in the control group, the insulin level increased by 38.64% compared to the data at birth, in groups 2 and 3, respectively, by 31.49 and 22.48%. At the age of one month, the level of pancreatic hormone, compared with baseline data, increased by an average of 3.87–5.30%, at the age of two months – by 2.27–8.66%. In subsequent age periods, the concentration of this hormone changed slightly. Relatively low testosterone levels were recorded in the first six months (0.47–1.32 nmol/l). At the age of 6, 8 and 12 months, the testosterone content increased to 2.97–3.34, 3.78–4.29 and 9.84–12.15 nmol/l, respectively. The highest testosterone content was found at the age of 18 months (13.24–15.48 nmol/l).

The Effect of Adding Protected Amino Acids in the Rumen (Methionine and Lysine and their Mixtures) on Some Physiological Characteristics of Male Arabi Lambs

This study was conducted at the animal field of the Agriculture College / University of Basra / Karma Ali site for the period from 7/10/2019 to 1/5/2020 to investigation the effect of adding protected amino acids (methionine and lysine and their mixtures) on some physiological trails of male Arabi lambs. Sixteen male lambs with an average weight of (27.95) kg and an age of 5-6 months were selected, and randomly divided into four group (4 animals per group). The results indicated that there were no significant differences in the concentration of hemoglobin, packed cell volume, the number of red and white blood cells, cholesterol, triglycerides and the activity of the liver enzyme (ALT and AST) between the different treatments, while there was a significant (p <0.05) increase in the total protein and albumin concentration in the fourth treatment compared with the first treatment (control), while, there was a significant decrease (p <0.05) in the urea concentration for the fourth, third and second treatments compared with the first treatment. The concentrations of glucose, thyroxine and growth hormone increased significantly (p <0.05) in the fourth and second treatment compared with the first treatment. However, it can be concluded from the study that feeding the male lambs with 5g methionine or mixing it with lysine by 5g raises the concentration of glucose, growth hormones and thyroxine in the blood. Also, the levels of methionine and lysine used did not change the concentration of the studied biochemical parameters

The prevalence of autoimmune thyroiditis in adolescent girls with polycystic ovary syndrome.

Both polycystic ovary syndrome (PCOS) and autoimmune thyroiditis (AT) are reported to be common endocrinopathies. In recent years the number of publications assessing the coexistence of these two disease entities in adult women has been growing. There are many suggestions regarding pathophysiological mechanisms that can cause the relationship between AT and PCOS. However, there is still a lack of research among adolescent girls. The aim of the study was to analyze the occurrence of autoimmune thyroiditis in adolescent girls with PCOS. The study group included 80 girls diagnosed with PCOS (chronological age: 16.54 ± 1.00 years, BMI: 22.80 ± 3.27 kg/m2), and the control group - 64 regularly menstruating girls (chronological age: 16.71 ± 0.63 years, BMI: 24.8 ± 5.2 kg/m2). The thyroid function and morphology were assessed based on the concentration of thyroid stimulating hormone (TSH), free thyroxine (fT4), anti thyroid peroxidase (anti-TPO), anti-thyroglobulin (anti-TG) antibodies and ultrasound scan of the thyroid gland. AT was diagnosed in 18 (22.5%) girls from the study group and nine (14.06%) from the control group (p > 0.05). Positive anti-TPO titer was observed more often in the study group [21 patients (26.25%)] than in the control group [9 girls (14.06%)] (p = 0.054). Moreover, an abnormal ultrasound scan of the thyroid gland characteristic for AT was found in 18 girls from the study group (22.50%) and 8 girls from the control group (12.50%) (p > 0.05). The results of the analyzed studies do not confirm a significant relationship between PCOS and AT in adolescent girls. However, in the group of girls with PCOS, autoimmune process exponents were more frequent (anti-TPO), reaching the borderline level of statistical significance.

Functional Characterization of the Novel and Specific Thyroid Hormone Transporter SLC17A4.

Background: A recent genome-wide association study identified the SLC17A4 locus associated with circulating free thyroxine (T4) concentrations. Human SLC17A4, being widely expressed in the gastrointestinal tract, was characterized as a novel triiodothyronine (T3) and T4 transporter. However, apart from the cellular uptake of T3 and T4, transporter characteristics are currently unknown. In this study, we delineated basic transporter characteristics of this novel thyroid hormone (TH) transporter. Methods: We performed a broad range of well-established TH transport studies in COS-1 cells transiently overexpressing SLC17A4. We studied cellular TH uptake in various incubation buffers, TH efflux, and the inhibitory effects of different TH metabolites and known inhibitors of other TH transporters on SLC17A4-mediated TH transport. Finally, we determined the effect of tunicamycin, a pharmacological inhibitor of N-linked glycosylation, and targeted mutations in Asn residues on SLC17A4 function. Results: SLC17A4 induced the cellular uptake of T3 and T4 by ∼4 times, and of reverse (r)T3 by 1.5 times over control cells. The uptake of T4 by SLC17A4 was Na+ and Cl- independent, stimulated by low extracellular pH, and reduced by various iodothyronines and metabolites thereof, particularly those that contain at least three iodine moieties irrespective of the presence of modification at the alanine side chain. None of the classical TH transporter inhibitors studied attenuated SLC17A4-mediated TH transport. SLC17A4 also facilitates the efflux of T3 and T4, and to a lesser extent of 3,3'-diiodothyronine (T2). Immunoblot studies on lysates of transfected cells cultured in absence or presence of tunicamycin indicated that SLC17A4 is subject to N-linked glycosylation. Complementary mutational studies identified Asn66, Asn75, and Asn90, which are located in extracellular loop 1, as primary targets. Conclusions: Our studies show that SLC17A4 facilitates the transport of T3 and T4, and less efficiently rT3 and 3,3'-T2. Further studies should reveal the physiological role of SLC17A4 in TH regulation.

Cord Blood Thyroid Hormones and Neurodevelopment in 2-Year-Old Boys and Girls.

Objective: Thyroid hormones are essential for neurodevelopment in early life. However, the impact of mild alterations in neonatal thyroid hormones on infant neurodevelopment and its sex dimorphism is unclear. We aimed to assess whether mild variations in neonatal thyroid hormones of term-born newborns with maternal euthyroid are related to neurodevelopment in 2-year-old boys and girls.Methods: This study used data from 452 singleton term-born infants of mothers with normal thyroid function in Shanghai, China, and their follow-up measure at the age of 2 years. Cord serum concentrations of free thyroxine (FT4), free triiodothyronine (FT3), thyroid-stimulating hormone (TSH), and thyroid peroxidase antibody (TPOAb) were measured by chemiluminescent microparticle immunoassays and classified into three groups: the low (1st, Q1), middle (2nd−4th, Q2–Q4), and high (5th, Q5) quintiles. Neurodevelopment indices were assessed using the Ages and Stages Questionnaire, third edition (ASQ-3), at 24 months of age.Results: Compared to infants with thyroid hormones in the middle (Q2–Q4), boys with FT4 in the lowest quintile had 5.08 (95% CI: 1.37, 8.78) points lower scores in the communication domain, 3.25 (0.25,6.25) points lower scores in the fine motor domain, and 3.84 (0.04, 7.64) points lower scores in the personal-social domain, respectively. Boys with FT3 in the highest quintile had 4.46 (0.81, 8.11) points increase in the personal-social domain. These associations were not observed in girls. No associations were observed between cord blood serum TSH and ASQ-assessed neurodevelopment in the boys or the girls.Conclusions: Mild alterations in thyroid hormones of newborns were associated adversely with neurodevelopment in boys, suggesting the importance of optimal thyroid hormone status for neurodevelopment in early life.

Persisting neuroendocrine abnormalities and their association with physical impairment 5\xa0years after critical illness

BackgroundCritical illness is hallmarked by neuroendocrine alterations throughout ICU stay. We investigated whether the neuroendocrine axes recover after ICU discharge and whether any residual abnormalities associate with physical functional impairments assessed 5 years after critical illness.MethodsIn this preplanned secondary analysis of the EPaNIC randomized controlled trial, we compared serum concentrations of hormones and binding proteins of the thyroid axis, the somatotropic axis and the adrenal axis in 436 adult patients who participated in the prospective 5-year clinical follow-up and who provided a blood sample with those in 50 demographically matched controls. We investigated independent associations between any long-term hormonal abnormalities and physical functional impairments (handgrip strength, 6-min walk distance, and physical health-related quality-of-life) with use of multivariable linear regression analyses.ResultsAt 5-year follow-up, patients and controls had comparable serum concentrations of thyroid-stimulating hormone, thyroxine (T4), triiodothyronine (T3) and thyroxine-binding globulin, whereas patients had higher reverse T3 (rT3, p = 0.0002) and lower T3/rT3 (p = 0.0012) than controls. Patients had comparable concentrations of growth hormone, insulin-like growth factor-I (IGF-I) and IGF-binding protein 1 (IGFBP1), but higher IGFBP3 (p = 0.030) than controls. Total and free cortisol, cortisol-binding globulin and albumin concentrations were comparable for patients and controls. A lower T3/rT3 was independently associated with lower handgrip strength and shorter 6-min walk distance (p ≤ 0.036), and a higher IGFBP3 was independently associated with higher handgrip strength (p = 0.031).ConclusionsFive years after ICU admission, most hormones and binding proteins of the thyroid, somatotropic and adrenal axes had recovered. The residual long-term abnormality within the thyroid axis was identified as risk factor for long-term physical impairment, whereas that within the somatotropic axis may be a compensatory protective response. Whether targeting of the residual abnormality in the thyroid axis may improve long-term physical outcome of the patients remains to be investigated.Trial registration ClinicalTrials.gov: NCT00512122, registered on July 31, 2007 (https://www.clinicaltrials.gov/ct2/show/NCT00512122).Graphical

Association of phthalate exposure with thyroid function during pregnancy.

The extent of thyroid disruptive effects of phthalates during pregnancy remains unclear. To investigate the association of maternal urinary phthalates with markers of the thyroid system during early pregnancy. Urinary concentrations of phthalate metabolites and serum concentrations of thyroid stimulating hormone (TSH), free and total thyroxine (FT4 and TT4) and free and total triiodothyronine (FT3 and TT3) were measured in pregnant women in early pregnancy in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy study (2007-ongoing), a population-based prospective cohort. In the 1,996 included women, higher di-ethyl-hexyl phthalate (DEHP) metabolites were associated with a lower FT4 (β [SE] for the molar sum: -0.13 [0.06], P=0.03) and a higher TSH/FT4 ratio (0.003 [0.001], P=0.03). Higher concentrations of di-iso-nonyl phthalate (DINP) metabolites were associated with a lower TT4 (β [SE] for the molar sum: 0.93 [0.44], P=0.03) as well as with lower TT4/FT4 and TT4/TT3 ratios. Higher metabolites of both dibutyl and butyl-benzyl phthalate (DBP and BBzP) were associated with lower T4/T3 ratio (free and total) and higher FT4/TT4 and FT3/TT3 ratios. A higher diisononyl cyclohexane dicarboxylate (DINCH) metabolite concentration was associated with a higher TT3. These results translate results from experimental studies suggesting that exposure to phthalates may interfere with the thyroid system during pregnancy. This is also true for compounds that have been introduced to replace known disruptive phthalates. Further experimental studies should take into account the human evidence to better investigate the potential underlying mechanisms of thyroid disruption by phthalates.

Abnormal Cardiac Repolarization in Thyroid Diseases: Results of an Observational Study.

Background: The relationship between thyroid function and cardiac disease is complex. Both hypothyroidism and thyrotoxicosis can predispose to ventricular arrhythmia and other major adverse cardiovascular events (MACE), so that a U-shaped relationship between thyroid signaling and the incidence of MACE has been postulated. Moreover, recently published data suggest an association between thyroid hormone concentration and the risk of sudden cardiac death (SCD) even in euthyroid populations with high-normal FT4 levels. In this study, we investigated markers of repolarization in ECGs, as predictors of cardiovascular events, in patients with a spectrum of subclinical and overt thyroid dysfunction.Methods: Resting ECGs of 100 subjects, 90 patients (LV-EF > 45%) with thyroid disease (60 overt hyperthyroid, 11 overt hypothyroid and 19 L-T4-treated and biochemically euthyroid patients after thyroidectomy or with autoimmune thyroiditis) and 10 healthy volunteers were analyzed for Tp-e interval. The Tp-e interval was measured manually and was correlated to serum concentrations of thyroid stimulating hormone (TSH), free triiodothyronine (FT3) and thyroxine (FT4).Results: The Tp-e interval significantly correlated to log-transformed concentrations of TSH (Spearman's rho = 0.30, p < 0.01), FT4 (rho = −0.26, p < 0.05), and FT3 (rho = −0.23, p < 0.05) as well as log-transformed thyroid's secretory capacity (SPINA-GT, rho = −0.33, p < 0.01). Spearman's rho of correlations of JT interval to log-transformed TSH, FT4, FT3, and SPINA-GT were 0.51 (p < 1e−7), −0.45 (p < 1e−5), −0.55 (p < 1e−8), and −0.43 (p < 1e−4), respectively. In minimal multivariable regression models, markers of thyroid homeostasis correlated to heart rate, QT, Tp-e, and JT intervals. Group-wise evaluation in hypothyroid, euthyroid and hyperthyroid subjects revealed similar correlations in all three groups.Conclusion: We observed significant inverse correlations of Tp-e and JT intervals with FT4 and FT3 over the whole spectrum of thyroid function. Our data suggest a possible mechanism of SCD in hypothyroid state by prolongation of repolarization. We do not observe a U-shaped relationship, so that the mechanism of SCD in patients with high FT4 or hyperthyroidism seems not to be driven by abnormalities in repolarization.

Effects of Ambient Temperature on the Performance and Thermoregulatory Responses of Commercial and Crossbred (Brazilian Piau Purebred Sires × Commercial Dams) Growing-Finishing Pigs.

Simple SummaryPhysiological responses to heat stress are affected by breed. Therefore, crossbreeding genetically improved lines with tropically adapted breeds of pigs may be a strategy to attenuate the impact of high ambient temperatures on pig production. Although some studies have evaluated thermotolerance in tropically adapted breeds, it is not yet clear to which extent improved tolerance to heat stress is a consequence of a greater ability to equilibrate thermogenesis and thermolysis, or if it is a consequence of decreased growth performance. Although there was no interaction for performance, thermoregulatory responses, and blood parameters, our results evidenced that ambient temperature effects on carcass parameters were modulated by the pigs’ genotype. Because protein deposition significantly decreased in response to high ambient temperature in commercial pigs, and was not affected by ambient temperature in Piau crossbred pigs, our study suggests increased thermotolerance of Piau crossbred pigs.The study aimed at evaluating the effects of high ambient temperature (HT: 30 °C) on the thermoregulatory responses and performance of commercial and Piau crossbred (Brazilian Piau breed sires × commercial genotype dams) growing pigs. Commercial and Piau crossbred pigs were reared under thermoneutral (TN: 22 °C) or HT conditions during a 14-day experimental period. Feeding (daily) and animals (beginning and end) were weighted to obtain performance parameters. Skin and rectal temperatures, respiratory rate, and blood parameters were also measured. At the end of the trial (day 15), the animal’s backfat thickness (BF) and loin eye area (LEA) were measured. No interaction (p > 0.05) between the genetic group and ambient temperature was observed for any performance trait. Irrespective of ambient temperature, Piau crossbred pigs had a similar feed intake (ADFI, 2615 g/day, on average; p > 0.05), lower daily weight gain (ADG, −234 g/day; p < 0.01), and a higher feed conversion ratio (FCR, +0.675 g/g; p < 0.01). There was interaction (p = 0.01) between genotype and ambient temperature for the LEA that decreased significantly in response to HT in commercial pigs (−6.88 cm2) and did not differ in response to ambient temperature in Piau crossbred pigs (29.14 cm2, on average; p > 0.05). Piau crossbred pigs had greater BF (+7.2 mm; p < 0.01) than commercial pigs. Regardless of the genetic group, exposure of pigs to HT resulted in decreased ADFI (−372 g/day; p < 0.01), ADG (−185 g/day; p < 0.01), and a higher FCR (+0.48 g/g; p = 0.01). Ambient temperature did not affect lipid deposition. Pigs at HT had an increased respiratory rate (+38 bpm; p < 0.01) and a long-lasting increase in skin and rectal temperatures compared to TN pigs. Total concentrations of triiodothyronine (T3) and thyroxine (T4) were not affected by ambient temperature in commercial pigs, whereas Piau crossbred pigs kept at 30 °C had a transient decrease in both hormones at day 2 (p < 0.01). Serum cortisol concentrations were not affected (p > 0.05) by genotype nor ambient temperature. In summary, Piau crossbred pigs had lower efficiency using nutrients for growth in association with increased lipid deposition when compared to commercial pigs. In response to HT, commercial pigs had a decreased LEA, whereas no effect was observed for Piau crossbred pigs. Apart from that, commercial and Piau crossbred pigs had a similar magnitude of thermoregulatory responses activation in response to HT, evidencing their innate survival-oriented function.

Radioactive iodine dose and survival in cats with hyperthyroidism (2015-2020).

Radioactive iodine (131I) is the preferred treatment for feline hyperthyroidism but neither the optimal 131I dose nor consistent predictors of post-treatment azotaemia have been determined. The aims of the study were to evaluate the relationships between: (1) 131I dose and survival; and (2) pretreatment and post-treatment serum creatinine concentration. Medical records of hyperthyroid cats treated with 131I at a single referral hospital were reviewed. Information regarding signalment, body weight, pretreatment and post-treatment serum total thyroxine concentration (TT4), serum creatinine concentration, 131I dose and survival were determined. Multivariable Cox proportional hazards analysis was used to identify variables associated with survival. Multivariable linear regression analysis was used to identify variables associated with post-treatment serum creatinine concentration. One hundred and ninety-eight (79 male, 119 female) cats were treated for hyperthyroidism with 131I (median dose 138 MBq; interquartile range 92-168). Median survival time was 1153 days (range 16-1871). Post-treatment serum creatinine (P <0.001) and age (P = 0.049) were significantly associated with survival. Every 10 µmol/l increase in post-treatment serum creatinine concentration and every year increase in age was associated with a 1.07-fold (confidence interval [CI] 1.04-1.11) and 1.17-fold (CI 1.00-1.37) increase in the daily hazard of death, respectively. Pretreatment serum creatinine concentration was directly, and post-treatment serum TT4 concentration was inversely, associated with post-treatment serum creatinine concentration. Every 1 μmol/l increase in pretreatment serum creatinine concentration was associated with an increase in post-treatment serum creatinine concentration of 0.7 μmol/l (SE 0.17; P <0.001). Conversely, every 1 nmol/l decrease in post-treatment serum TT4 concentration was associated with a 1.2 μmol/l (SE 0.61; P <0.001) increase in post-treatment serum creatinine concentration. Post-treatment serum TT4 concentration was associated with post-treatment azotaemia, which was associated with survival. Although 131I dose was not directly associated with survival, dosing strategies that minimise post-treatment hypothyroidism and azotaemia could improve patient survival.

Comparative effect of zinc supplementation by hydroxy and inorganic sources on nutrient utilisation, mineral balance, growth performance and growth biomarkers in pre-ruminant calves

ABSTRACT Zinc (Zn), an important microelement in ruminant diet, plays a critical role in various enzymes, hormones and functional proteins involved in nutrient metabolism. The present study was conducted to assess the effect of zinc hydroxychloride (Zn5(OH)8Cl2·H2O [ZnOHCl] and zinc sulphate (ZnSO4) on nutrient utilisation, mineral metabolism and biomarkers pertaining to growth performance in pre-ruminant crossbred calves. Twenty-four crossbred calves [body weight (BW); 31.03 ± 4.30 kg; age 10 d] were randomly allocated to four treatment groups (n = 6), i.e. no supplementation of Zn (0 mg/kg dry matter [DM]), 80 mg/kg DM Zn as ZnSO4(ZnS-80), 40 mg/kg DM Zn as ZnOHCl (ZnH-40) and 80 mg/kg DM Zn as ZnOHCl (ZnH-80) for 90 d experimental period. Results showed that dietary Zn supplementation improved (p < 0.05) feed intake, BW, average daily gain, heart girth, body length, plasma growth hormone, insulin-like growth factor and thyroxin concentration; however, nutrient digestibility remained unaffected among the groups. Addition of Zn increased (p < 0.05) Zn retention and plasma Zn concentration without affecting retention and plasma concentration of other minerals. Retention of Zn was the highest in ZnH-80 group followed by ZnH-40, ZnS-80 and lowest in control group. Overall results of the present study indicate that regardless of sources and levels, Zn supplementation increased growth performance, plasma Zn concentration and hormones levels in pre-ruminant crossbred calves. However, supplementation of hydroxy Zn at 40 mg/kg DM had similar effect as produced by ZnSO4 or ZnOHCl at a supplementation level of 80 mg/kg DM. Therefore, from the present study it can be concluded that ZnOHCl can be used as a Zn source for pre-ruminant calves at a lower dose compared to ZnSO4.

Functional State of Rat Heart Mitochondria in Experimental Hyperthyroidism.

In this work, the effect of thyroxine on energy and oxidative metabolism in the mitochondria of the rat heart was studied. Hyperthyroidism was observed in experimental animals after chronic administration of T4, which was accompanied by an increase in serum concentrations of free triiodothyronine (T3) and thyroxine (T4) by 1.8 and 3.4 times, respectively. The hyperthyroid rats (HR) had hypertrophy of the heart. In HR, there was a change in the oxygen consumption in the mitochondria of the heart, especially when using palmitoylcarnitine. The assay of respiratory chain enzymes revealed that the activities of complexes I, I + III, III, IV increased, whereas the activities of complexes II, II + III decreased in heart mitochondria of the experimental animals. It was shown that the level of respiratory complexes of the electron transport chain in hyperthyroid rats increased, except for complex V, the quantity of which was reduced. The development of oxidative stress in HR was observed: an increase in the hydrogen peroxide production rate, increase in lipid peroxidation and reduced glutathione. The activity of superoxide dismutase in the heart of HR was higher than in the control. At the same time, the activity of glutathione peroxidase decreased. The obtained data indicate that increased concentrations of thyroid hormones lead to changes in energy metabolism and the development of oxidative stress in the heart of rats, which in turn contributes to heart dysfunction.

Thyroid-Related Hormone Levels in Clinical Patients With Moderately Severe-to-Profound Sudden Sensorineural Hearing Loss: A Prospective Study.

Objectives: Sudden sensorineural hearing loss (SSNHL) is a common otological emergency, causing a measure of hearing loss and affecting the quality of life. This study aims to investigate the association of thyroid-related hormone levels with moderately severe-to-profound SSNHL.Methods: The study included 70 patients with moderately severe-to-profound SSNHL and 100 age- and sex-matched healthy controls. Peripheral venous blood samples were taken from the participants, and their thyroid-related hormone levels were measured at admission and 1 week after treatment.Results: In moderately severe-to-profound SSNaHL patients, the concentrations of total triiodothyronine (TT3), total thyroxine (TT4), free triiodothyronine (FT3), and thyroid-stimulating hormone (TSH) (all P < 0.05) were significantly lower than in the control group. The TT3, TT4, FT3, and TSH levels were significantly higher in the effective group than in the ineffective group (all P < 0.05). Linear correlation analysis revealed that TSH level (R = 0.707, P < 0.05) elevation after treatment successfully predicted a favorable outcome of hearing recovery. Logistic regression analyses suggested low FT3 and TSH levels to be independent occurrence predictors, while the increase of TSH level may be an independent favorable outcome predictor.Conclusions: The results suggest that low FT3 and TSH levels are risk factors for moderately severe-to-profound SSNHL. By discovering the positive association between TSH elevation and hearing recovery, along with the potential novel predictors of FT3 and TSH, our study may contribute valuable insights to the research and treatment of moderately severe-to-profound SSNHL.

Exposure to common-use pesticides, manganese, lead, and thyroid function among pregnant women from the Infants' Environmental Health (ISA) study, Costa Rica

BackgroundPesticides and metals may disrupt thyroid function, which is key to fetal brain development. ObjectivesTo evaluate if current-use pesticide exposures, lead and excess manganese alter free thyroxine (FT4), free triiodothyronine (FT3), and thyroid stimulating hormone (TSH) concentrations in pregnant women from the Infants' Environmental Health Study (ISA). MethodsAt enrollment, we determined women's (n = 400) specific-gravity corrected urinary pesticide (μg/L) metabolite concentrations of mancozeb (ethylene thiourea (ETU)), pyrimethanil, thiabendazole, chlorpyrifos, synthetic pyrethroids, and 2,4-D. We also measured manganese hair (MnH) (μg/g) and blood (MnB) (μg/L), and blood lead (PbB) (μg/L) concentrations. To detect an immediate and late effect on thyroid homeostasis, we determined TSH, FT4 and FT3 in serum obtained at the same visit (n = 400), and about ten weeks afterwards (n = 245). We assessed associations between exposures and outcomes with linear regression and general additive models, Bayesian multivariate linear regression, and Bayesian kernel machine regression. ResultsAbout 80%, 94%, and 100% of the women had TSH, FT4, and FT3 within clinical reference ranges, respectively. Women with higher urinary ETU, and pyrimethanil-metabolites, had lower FT4: β = −0.79 (95%CI = −1.51, −0.08) and β = −0.29 (95%CI = −0.62, −0.03), respectively, for each tenfold increase in exposure. MnB was positively associated with FT4 (β = 0.04 (95%CI = 0.00, 0.07 per 1 μg/L increase), and women with high urinary pyrethroid-metabolite concentrations had decreased TSH (non-linear effects). For the late-effect analysis, metabolites of pyrethroids and chlorpyrifos, as well as MnH, and PbB were associated decreased TSH, or increased FT4 and/or FT3. DiscussionMancozeb (ETU) and pyrimethanil may inhibit FT4 secretion (hypothyroidism-like effect), while chlorpyrifos, pyrethroids, MnB, MnH, PbB and Mn showed hyperthyroidism-like effects. Some effects on thyroid homeostasis seemed to be immediate (mancozeb (ETU), pyrimethanil, MnB), others delayed (chlorpyrifos, MnH, PbB), or both (pyrethroids), possibly reflecting different mechanisms of action.

Iron Deficiency Is a Risk Factor for Thyroid Dysfunction During Pregnancy: A Population-Based Study in Belgium.

Background: Iron deficiency affects thyroid hormone synthesis by impairing the activity of the heme-dependent thyroid peroxidase. The prevalence of iron deficiency is elevated particularly in pregnant women. This study aimed to investigate the effects of iron status on thyroid function in a nationally representative sample of mildly iodine-deficient pregnant women. Methods: The study population comprised a sample of pregnant women in Belgium during the first and third trimesters of pregnancy (n = 1241). Women were selected according to a multistage proportional-to-size stratified and clustered sampling design. Urine and blood samples were collected, and a questionnaire was completed face to face with the study nurse. Concentrations of free thyroxine (fT4), total thyroxine (T4), free triiodothyronine, thyrotropin (TSH), thyroglobulin (Tg), thyroid peroxidase antibodies, Tg antibodies, hemoglobin, serum ferritin (SF), soluble transferrin receptor, urinary iodine concentrations (UICs) were measured and body iron stores (BIS) were calculated. Results: Median UICs were 117 and 132 μg/L in the first and third trimesters of pregnancy, respectively (p < 0.05). The frequency of SF <15 μg/L was 6.2% in the first trimester and 39.6% in the third trimester of pregnancy (p < 0.05). UIC was a significant predictor of serum Tg concentrations (p < 0.01) but not of thyroid hormone or TSH concentrations. The frequency of fT4<percentile 10th in the third trimester of pregnancy was 24% and 14% in pregnant women with negative BIS and positive BIS, respectively (p < 0.05). SF and BIS were significant predictors of fT4 and T4 in the first trimester of pregnancy (p < 0.05). Hemoglobin was a significant predictor of fT4 in both trimesters (p < 0.01) and for T4 in the third trimester (p = 0.015). Conclusion: Iron deficiency, but not mild iodine deficiency, is a determinant of serum fT4 and T4 in pregnant women. Correcting iron deficiency may help to maintain optimal thyroid function, in addition to preventing anemia during pregnancy.

Thifluzamide exposure induced neuro-endocrine disrupting effects in zebrafish (Danio rerio).

Thifluzamide is widely used fungicide and frequently detected in aquatic system. In this study, the toxicity of fungicide thifluzamide to non-targeted aquatic organisms was investigated for neuroendocrine disruption potentials. Here, zebrafish embryos were exposed to a series of concentrations of thifluzamide for 6days. The results showed that both the development of embryos/larvae and the behavior of hatched larvae were significantly affected by thifluzamide. Importantly, the decreased activity of acetylcholinesterase (AchE) and the increased contents of neurotransmitters such as serotonin (5-HT) and norepinephrine (NE), along with transcriptional changes of nervous system related genes were observed following 4 days exposure to thifluzamide. Besides, the decreased contents of triiodothyronine (T3) and thyroxine (T4) in whole body, as well as significant expression alteration in hypothalamic-pituitary-thyroid (HPT) axis associated genes were discovered in zebrafish embryos after 4 days of exposure to thifluzamide. Our results clearly demonstrated that zebrafish embryos exposed to thifluzamide could disrupt neuroendocrine, compromise behavior and induce developmental abnormality, suggesting impact of this fungicide on developmental programming in zebrafish.