Serum Triiodothyronine Concentrations Research Articles

Effects of high doses of levothyroxine sodium on serum concentrations of triiodothyronine and thyroxine in horses.

To investigate the effect of high doses of orally administered levothyroxine sodium (LT4) on serum concentrations of triiodothyronine (T3) and thyroxine (T4) in euthyroid horses. 12 healthy adult horses. 10 horses initially received water (vehicle) or 240 mg (5X treatment) or 480 mg (10× treatment) of LT4, and blood samples were collected at baseline (0 hours) and 0.5, 1, 2, 4, 6, 8, 10, 12, 18, 24, 48, 72, 96, and 120 hours after treatment to measure serum T3 and T4 concentrations. Three horses then received 480 mg of LT4 for 14 days, and T4 concentration was measured on days 0, 14, 21, 28, and 35. Changes in T3 and T4 concentrations were compared over time and among treatments. One-time administration of LT4 resulted in variable but significant increases in both T3 and T4 concentrations for up to 120 hours; however, T3 and T4 concentrations rarely exceeded reference intervals with either treatment. Prolonged administration of 480 mg of LT4 resulted in a 15-fold increase in T4 concentration after 14 days, but concentration returned to day 0 values within 21 days after LT4 administration was discontinued. In euthyroid horses, administration of a high dose of LT4 resulted in mild increases in thyroid hormone concentrations; however, prolonged administration of high doses of LT4 resulted in markedly increased thyroid hormone concentrations that returned to pretreatment values within 3 weeks after discontinuation of LT4 administration. These results indicated complex kinetics of LT4 and suggested a possible saturation of T4 excretion in euthyroid horses.

A Comparative Study On Biochemical Parameters For Mature California And Chinchilla Rabbits In Sohag Governorate.

Rabbit as homeothermic species is able to keep its core body temperature within ± 1°C regulatory range. In Upper Egypt where high ambient temperature particularly at summer months, rabbit breeding ceases, by virtue of its fur, there is certain inability to dissipate excess body heat. Under uncontrolled ambient environment, most of the observed mortality at summer is due to heat stasis. In this study, we compared white (California) to black (Chinchilla) mature breeds of rabbits. Blood picture and serum hormonal profiles were assessed. The results showed many similarities between the two breeds in terms of blood picture, the serum concentration of tri-iodothyronine (T3) and thyroxine (T4), but T3/T4 ratio was higher and corticosterone was lower in California than Chinchilla rabbits (P<0.5). Heat loss was higher in male California than other rabbits. The overall results referred to the higher ability of California breed to withstand heat stress compared to Chinchilla rabbits.

Effects of Thyroid Hormone Treatment on Diaphragmatic Efficiency in Mechanically Ventilated Subjects With Nonthyroidal Illness Syndrome.

Several respiratory abnormalities can be present in primary hypothyroidism and can be reversed with adequate hormone treatment. However, the role of thyroid hormone replacement therapy on the respiratory system in patients with nonthyroidal illness syndrome is still unclear. This physiologic study evaluated the effect of thyroid hormone treatment on respiratory muscle function in subjects with nonthyroidal illness syndrome and while on mechanical ventilation. The primary end point was neuromechanical efficiency, which provides an estimate of the efficiency of diaphragmatic contraction. Secondary end points were the transdiaphragmatic pressure-time product and the swing of the electrical activity of the diaphragm, which reflect the work of breathing and inspiratory effort, respectively. Fifteen subjects on mechanical ventilation for ≥48 h and with a diagnosis of nonthyroidal illness syndrome who had a failed spontaneous breathing trial, received intravenous triiodothyronine. The hormone was administered as an intravenous bolus of 0.4 μg/kg triiodothyronine, followed by continuous perfusion at 0.6 μg/kg for 24 h. Neuromechanical efficiency was calculated as the ratio between the drop in airway pressure during an expiratory occlusion and the corresponding electrical activity of the diaphragm peak. Recordings were taken at baseline and after 3, 6, and 24 h. After study completion, free triiodothyronine serum concentrations increased in all the subjects (mean ± SD increase, 0.84 ± 0.34 pg/mL). Neuromechanical efficiency showed no significant changes throughout the study (mean ± SD baseline, 1.40 ± 0.87 cm H2O/μV; 3 h, 1.28 ± 0.64 cm H2O/μV; 6 h, 1.33 ± 0.87 cm H2O/μV; 24 h, 1.41 ± 0.96 cm H2O/μV). Similarly, no variations in transdiaphragmatic pressure-time product per min (mean ± SD baseline, 238.1 ± 124 cm H2O × s/min; 3 h, 242.5 ± 140.3 cm H2O × s /min; 6 h, 247.5 ± 161.7 cm H2O × s/min; 24 h, 281.2 ± 201.2 cm H2O × s/min) or swing of electrical activity of the diaphragm (mean ± baseline, 20.9 ± 13.1 μV; 3 h, 17.2 ± 8.3 μV; 6 h, 17.4 ± 11.3 μV; 24 h, 20.3 ± 13.7 μV) were observed during hormone administration. In the subjects on mechanical ventilation who were admitted to the ICU with nonthyroidal illness syndrome, thyroid hormone replacement treatment did not yield any benefit on respiratory muscle function when assessed by neuromechanical efficiency, which indicated that, in these subjects restoring normal levels of serum thyroid hormones is debatable. (ClinicalTrials.gov registration NCT03157466.).

Chavibetol corrects thyrotoxicosis through alterations in thyroid peroxidase

Thyrotoxicosis is a clinical syndrome that commonly results from excess secretion and/or release of thyroid hormones in the circulation. It affects most of the body systems and if not treated properly may lead to serious health problems. In this investigation, we isolated a phenolic compound, chavibetol (CHV) from Piper betel leaf and evaluated its possible ameliorative effects in thyrotoxicosis of rats. Adult female rats were rendered thyrotoxic by the administration of L-thyroxine (L-T4) at 500μg/kg/day, i.p., for 12days, and then chavibetol (20.0mg/kg, p.o.) was administered for 2weeks. L-T4 administration elevated the concentration of serum thyroxine and triiodothyronine, activities of alanineaminotransferase and aspartate aminotransferase, and decreased the thyrotropin level as well as the expression of thyroid peroxidase (TPO). Further, it increased the activities of hepatic 5'mono-deiodinase-I, glucose-6--phosphatase, sodium-potasium-ATPase, and lipid peroxidation, and depleted the cellular antioxidants. However, chavibetol treatment to thyrotoxic rats normalized almost all these indices including TPO and also preserved the integrity of thyroid tissues suggesting its potential to correct thyrotoxicosis. Effects of CHV were more or less similar to a conventional antithyroid drug, propylthiouracil (PTU).

Graves' Disease: Can It Be Cured?

Whether or not Graves' hyperthyroidism can be really cured, depends on the definition of “cure.” If eradication of thyroid hormone excess suffices for the label “cure,” then all patients can be cured because total thyroidectomy or high doses of 131I will abolish hyperthyroidism albeit at the expense of creating another disease (hypothyroidism) requiring lifelong medication with levothyroxine. I would not call this a “cure,” which I would like to define as a state with stable thyroid stimulating hormone (TSH), free thyroxine, and triiodothyronine serum concentrations in the normal range in the absence of any thyroid medication. Surgery and radioiodine are unlikely to result in so-defined cures, as their preferable aim as stated in guidelines is to cause permanent hypothyroidism. Discontinuation of antithyroid drugs is followed by 50% recurrences within 4 years; before starting therapy the risk of recurrences can be estimated with the Graves' Recurrent Events After Therapy (GREAT) score. At 20-year follow-up about 62% had developed recurrent hyperthyroidism, 8% had subclinical hypothyroidism, and 3% overt hypothyroidism related to TSH receptor blocking antibodies and thyroid peroxidase antibodies. Only 27% was in remission, and might be considered cured. If the definition of “cure” would also include the disappearance of thyroid antibodies in serum, the proportion of cured patients would become even lower.

Prescribing Therapy for Hypothyroidism: Influence of Physician Characteristics.

Physician characteristics and perceptions and their effect on choice of therapies for patients with thyroid cancer have been well studied. Some data also exist about physician characteristics and prescribing treatment for subclinical hypothyroidism. The effect of physician characteristics on prescribing thyroid preparations for treating overt hypothyroidism is less studied. Members of the American Thyroid Association were surveyed in 2017. Physicians were presented with 13 different theoretical patients with hypothyroidism and asked to choose among six therapeutic options, including levothyroxine, synthetic combination therapy, thyroid extract, and liothyronine monotherapy. The 13 patient scenarios incorporated parameters that potentially provide reasons for considering combination therapy (presence of symptoms, low serum triiodothyronine concentration, and documentation of deiodinase polymorphisms). Repeated-measures logistic regression analysis was performed to examine the prescribing of the various therapies. Data regarding the responding physicians were also collected. These data included number of years in practice, country of practice, and specialty. Multivariate repeated-measures logistic regression analysis of prescribing patterns was also conducted controlling for all patient and physician characteristics. Of the 389 survey respondents, 93% prescribed therapy for hypothyroidism. Fifty-three percent of respondents had been in practice for >20 years, and 23% had been in practice for 11-20 years. Sixty-four percent practiced in North America, and 18% practiced in Europe. Eight-six percent were endocrinologists, and 5% were surgeons. In multivariate analysis, physicians from North America were both more likely to prescribe any triiodothyronine-containing therapies (odds ratio [OR] = 1.8 [confidence interval (CI) 1.3-2.4]) and more likely to add liothyronine to levothyroxine therapy (OR = 1.9 [CI 1.2-2.9]). In addition, they were more likely to prescribe desiccated thyroid extract or liothyronine monotherapy (OR = 1.7 [CI 1.0-2.9]). A previous analysis of this survey showed that patient characteristics profoundly affect physician prescribing patterns. The current multivariate analysis shows that physician characteristics affect prescribing patterns. Whether this is due to impact upon physicians of patient-related experiences, media exposure, influence from pharmaceutical companies, educational activities, or other concerns cannot be determined. However, these results have potential importance for understanding physician-patient interactions at a time when the benefits and risks of triiodothyronine-containing therapies have not been fully documented.

PSXVII-30 Effects of dietary supplementation of yeast chromium and dihydropyridine on serum biochemical indices and HSP70 mRNA expression of lactating dairy cows in summer.

The objective of this study is to evaluate the effects of dietary supplementation of dihydropyridine and yeast chromium on serum biochemical indices and heat stress protein (HSP) concentration of lactating Holstein dairy cows in summer. Twenty-four lactating cows were assigned to three treatments: control, yeast-chromium supplementation (Cr-Yeast, 8 mg/d) and dihydropyridine supplementation (Dih, 3.0 g/d). The trial was conducted during summer and included a 6 d adaption period, followed by a 46 d experimental period for samples and data collection. The temperature humidity index (THI) was daily recorded at 10:00, 12:00 and 15:00. Blood samples were collected from coccygeal vessels on d 29 (15:00) and d 44 (15:00), part of which were immediately centrifuged to collect the serum. Automatic electrochemical luminescence analyzer was used to measure the serum triiodothyronine and tetraiodothyronine concentration using the direct luminescence competition method, while serum concentration of alkaline phosphatase and creatine kinase (CK) was determined by using IFCC reference method. RNA was extracted from the red blood cells and qPCR was used for testing the HSP70 mRNA expression in blood. The average temperature-humidity indexes at 10:00, 12:00 and 15:00 were 81.4, 83.0 and 83.8, respectively, which indicated the moderate heat stress during experiment. Supplementation of dihydropyridine significantly decreased the serum concentration of CK on d 29 (P < 0.05), while feeding dihydropyridine or yeast chromium decreased serum concentration of CK significantly on d 44 (P < 0.05). Treatments had no effects on blood HSP mRNA expression on d 29 (P > 0.05), while blood HSP mRNA expression on d 44 was significantly improved by the supplementation of chromium yeast (P < 0.05). In conclusion, supplementing yeast chromium and dihydropyridine decreased serum concentration of CK and improved antioxidant status in lactating dairy cows in summer.

Physician Choice of Hypothyroidism Therapy: Influence of Patient Characteristics.

Most endocrinologists encounter patients who are dissatisfied with their current hypothyroidism therapy and request combination therapy with either liothyronine (LT3) or thyroid extract. A survey of American Thyroid Association members was conducted in 2017. Respondents were presented with 13 scenarios describing patients with hypothyroidism and were asked to choose among six therapeutic options. The index patient was satisfied taking levothyroxine (LT4) therapy. Twelve variations introduced parameters that potentially provide reasons for considering combination therapy (presence of symptoms, low serum triiodothyronine concentration, documentation of deiodinase polymorphisms). Therapeutic options included (i) continuing LT4, (ii) increasing LT4, (iii) adding LT3 to a reduced LT4 dose, (iv) adding LT3 to the current LT4 dose, (v) replacing LT4 with thyroid extract, and (vi) replacing LT4 with LT3. Repeated-measures logistic regression analysis was performed to examine both the prescribing of LT4 (options i and ii) versus all other therapies and the choice of continuing LT4 (option i) versus either increasing LT4 (option ii), adding LT3 (options iii and iv), or replacing LT4 with thyroid extract or LT3 (options v and vi). Of the 389 survey respondents, 363 physicians prescribed therapy for hypothyroidism. For the index patient, 98% of physicians continued current LT4 therapy. However, as the patient scenario incorporated other patient characteristics, physicians opted to increase LT4 dose or prescribe other therapies. The tendency to prescribe alternative therapies was powerfully increased by patient symptoms (odds ratio = 25.6 [confidence interval 9-73], p < 0.0001). Older age and the presence of a comorbidity reduced the likelihood that an alternative therapy was prescribed (p = 0.0002 and <0.0001, respectively). All other characteristics, except athyreotic status, patient sex, and body mass index, significantly increased the likelihood that alternative therapies would be prescribed in multivariate analyses (p < 0.0001). Even with the acknowledged limitations of survey methodology, this analysis appears to show a marked increase in the willingness of physicians to prescribe combination therapy in specific circumstances. If current prescribing patterns do incorporate the use of therapies other than LT4, there is a critical need for more research into the benefits and risks of these therapies.

Responses of developmental and physiological traits to manipulated incubation conditions in broiler embryos at hypoxic high altitude

Abstract. The effects of hypoxia at increased altitude levels on the cardio-respiratory development of broiler embryos are distinct in comparison with those at sea level. The aim of the study was to investigate the effects of high incubation temperature (H) and oxygen supplementation (O) during hypoxic high altitude (HA) on developmental and physiological traits of embryos and hatching performance of embryonated hatching eggs in broilers at different embryonic stages. A total of 1280 eggs obtained from broiler breeders laid at sea level were used. Eggshell quality characteristics were measured for 20 eggs. The rest of the 1260 eggs were divided into seven incubation condition (IC) groups (180 eggs per group) including a control group at 37.8 ∘C and 21 % O2; O groups, with daily 1 h 23.5 % O2 supplementation at 37.8 ∘C as O0−11, O12−21, and O18−21; H groups at 38.5 ∘C high incubation temperature at 21 % O2 as H0−11, H12−21, and H18−21 from days 0 to 11, 12 to 21, and 18 to 21 of incubation, respectively. All groups were incubated in three different incubators at hypoxic HA. The effect of IC was determined on eggshell temperature, hatching performance, embryo development, right ventricular (RV) to total ventricular (TV) ratio, and blood parameters. The highest egg water loss and embryonic mortality and the lowest hatchability were in the H0−11 group, which depended on increased eggshell temperature during incubation. On day 18 of incubation, due to the decreased egg water loss in the O12−21 and O18−21 groups, there was an increase in hatchability in fertile eggs similar to the middle and late H groups. Towards the end of incubation, embryo/chick weights were not different and RV and TV weights increased in the treated groups, and the RV ∕ TV ratio changed between 15 and 26 %. At hatching, yolk sac weight increased in H0−11 and H12−21 groups. The O groups had the lowest serum tri-iodothyronine (T3) concentration as distinct from H groups. The serum thyroxine (T4) concentration increased in the treated groups, dependent on sex of the embryo. Blood hemoglobin concentration of O groups decreased relative to other groups. The hematocrit value was the lowest in the O12−21 and highest in the H12−21 groups. The H and O treatments during pre-hatch hypoxic HA condition can be positively evaluated on physiological traits of embryos after half of incubation depended on the timing of the IC exposure to the hatching eggs obtained from broiler breeders at sea level.

Growth performance, organ weights, and blood parameters of nursery pigs fed diets containing increasing levels of cold-pressed canola cake.

Oilseed cakes have high oil content, and thus their inclusion in swine can lead to reduced dietary inclusion of oil, and hence reduced cost of feed. An experiment was conducted to determine effects of including Brassica napus-derived cold-pressed canola cake (CPCC) in diets for nursery pigs on growth performance, organ weights relative to live body weight (BW), and blood parameters. A total of 160 pigs (initial BW: 7.8 ± 0.9 kg), which had been weaned at 21 d of age were housed in 40 pens (4 pigs/pen) and fed 4 diets (10 pens/diet) in a randomized complete block design for 35 d. The 4 diets were corn-soybean meal (SBM)-based basal diet and the basal diet with corn and SBM replaced by 20, 30, or 40% of CPCC. The diets were fed in 2 phases, Phase 1 from day 0 to 14 and Phase 2 from day 14 to 35; and were formulated to meet NRC (2012) nutrient recommendations for nursery pigs and to have the same net energy, standardized ileal digestible amino acid, and digestible P contents. Increasing inclusion of CPCC in diets was achieved by partial replacement of corn, SBM, limestone, and mono-calcium phosphate. Growth performance was determined by phase. On day 35, 1 pig from each pen was euthanized for determining organ weights and blood parameters. The CPCC contained 7.63% moisture, and on a dry matter basis, it (CPCC) contained 39.6% crude protein, 2.32% Lys, 0.74% Met, 1.63% Thr, 0.50% Trp, 16.0% ether extract, 20.7% neutral detergent fiber, and 14.9 µmol/g of glucosinolates. Increasing dietary CPCC from 0 to 40% linearly reduced (P < 0.05) overall (day 0 to 35) average daily gain and average daily feed intake (0.440 to 0.288 kg/d and 0.739 to 0.522 kg/d, respectively). Increasing dietary CPCC from 0 to 40% resulted in a linear increase (P < 0.05) in liver weight by 0.1 g/kg of BW and in thyroid gland weight by 2.2 mg/kg of BW, but in a linear reduction (P < 0.05) in serum tetraiodothyronine (T4) level by 0.2 ng/mL for each 1% increase in CPCC at 35 d of age. No differences were observed in heart and kidney weights relative to live BW, and in serum triiodothyronine (T3) concentration. In conclusion, increasing dietary CPCC from 0 to 40% by reducing corn and SBM levels resulted in depressed growth performance, increased metabolic activity in liver and thyroid gland, and reduced serum T4 level of pigs. Thus, the amounts of CPCC included in nursery pig diets should be based on targeted growth performance and cost of other feedstuffs in relation to that of CPCC.

Gas stunning with CO2 affected meat color, lipid peroxidation, oxidative stress, and gene expression of mitogen-activated protein kinases, glutathione S-transferases, and Cu/Zn-superoxide dismutase in the skeletal muscles of broilers

BackgroundMeat color and lipid peroxidation are important traits related to meat quality. CO2 concentration is a critical factor that can affect meat quality in the commercial use of gas stunning (GS). However, the effect and mechanism of CO2 stunning on meat color and lipid peroxidation during long-term storage remain poorly studied. We aimed to study the effects of GS methods, especially CO2 concentration, on meat color and meat lipid peroxidation in broilers during long-term storage at 4 °C and to explore the potential mechanism of meat color change via lipid peroxidation and the inner lipid peroxide scavenging system.MethodsEighteen broilers were sacrificed after exposure to one of the following gas mixtures for 90 s: 40% CO2 + 21% O2 + 39% N2 (G40%), 79% CO2 + 21% O2 (G79%), or no stunning (0% CO2, control). Meat color, serum variables, enzyme activities, and the gene expression of mitogen-activated protein kinase (MAPK), nuclear factor-erythroid 2-related factor 2 (Nrf2), glutathione S-transferase (GST) and superoxide dismutase (SOD) were determined.ResultsThe concentrations of serum triiodothyronine (T3, P = 0.03) and the ratio of serum free triiodothyronine/free thyroxine (FT3/FT4, P < 0.01) were decreased, whereas levels of serum cortisol (P < 0.01) were increased in the 40% CO2 group compared with the control group. Additionally, the thiobarbituric acid-reactive substances (TBARS) 3 d (P < 0.01) and TBARS 6 d (P = 0.01) in breast meat and the TBARS 3 d in thigh meat (P < 0.01) were increased in the 40% CO2 group compared with the control group. Serum T3 was negatively correlated with TBARS6 d both in the breast and thigh meat (r = − 0.63, P < 0.01 and r = − 0.47, P = 0.05 respectively). T3/T4 was negatively correlated with TBARS6 d in the breast meat and in the thigh meat (r = − 0.57, P = 0.01; and r = − 0.53, P = 0.03 respectively). Compared with the control group, Lightness (L*) 1 d (P = 0.03) and L*9 d (P < 0.01) were increased, whereas total chromatic aberration (E*) 1 d (P = 0.05) and E*3 d (P < 0.01) were decreased in the breast meat of both the G40% and G79% groups. The values of yellowness (b*) 3 d (P = 0.01), b*6 d (P < 0.01) and E*6 d (P < 0.01) in the thigh meat were lower in both the G40% and G79% groups than in the control group. In the breast muscle, the mRNA levels of c-Jun N-terminal kinase 2 (JNK2, P = 0.03), GSTT1 (P = 0.04), and SOD1 (P = 0.05) were decreased, and the mRNA levels of JNK1 (P = 0.07), Nrf2 (P = 0.09), and GSTA3 (P = 0.06) were slightly lower in both the G40% and G79% groups compared with the control group. However, among these genes, only the mRNA level of JNK1 was decreased in the G40% group compared with the control group and the G79% group (P = 0.03) in the thigh muscle.ConclusionsCompared with the control group, meat color quality in the breast meat was decreased, and the expression of genes in the MAPK/Nrf2/ARE (antioxidant responsive element) antioxidant pathway in breast muscle was partly suppressed by GS of both 40% and 79% CO2. However, oxidative stress and meat lipid peroxidation during storage were aggravated by GS with 40% CO2 compared to GS with 79% CO2 and no GS.

Abstract P266: Prevalence and Risk Factors of Thyroid Dysfunction in Older Adults in the Community

Context: Prevalence estimates and evidence informing treatment targets for thyroid dysfunction largely come from studies of middle-aged adults. There are limited data on the prevalence of thyroid dysfunction in older populations. Objective: To determine the prevalence of thyroid dysfunction and risk factors for abnormal thyroid tests in older adults. Methods: We conducted a cross-sectional analysis of data from participants aged 65 or older in the Atherosclerosis Risk in Communities (ARIC) study who attended visit 5 in 2011-2013. We measured serum concentrations of triiodothyronine (T3), free thyroxine (FT4), thyroid peroxidase antibody (Anti-TPO), and thyroid stimulating hormone (TSH) in 5,392 participants. We used multivariable linear and logistic regression to assess associations of demographic and clinical risk factors with thyroid hormone levels. Results: In this population of older adults (mean age 76; 56% women and 22% black), the prevalence of thyroid dysfunction was up to 25% when accounting for treated and untreated thyroid dysfunction categories. 15.6% reported use of medication for thyroid dysfunction. Among those not being treated, the prevalence of overt chemical hypothyroidism was 6.0% and subclinical hypothyroidism was 0.82%. Overt chemical hyperthyroidism and subclinical hyperthyroidism affected 0.26% and 0.78% of the population, respectively. Multivariable adjusted cardiovascular risk factor associations for TSH, FT4 and T3 levels are presented in Table . Men were less likely to be anti-TPO positive compared to women (OR=0.59, CI: 0.47,0.75, P&lt;0.001). Conclusions: There is a high prevalence of thyroid dysfunction in this older, community-based population. Prevalence of thyroid dysfunction and thyroid hormone levels vary with sex, race, age group and multiple cardiovascular risk factors. Accounting for these associations in the clinical setting might prove useful in improving thyroid function assessment in this age group.

Impact of seasonal thermal stress on physiological and blood biochemical parameters in pigs under different dietary energy levels.

The present study was formulated to find out the status of important season related thermal stress biomarkers of pure-bred (Hampshire) and crossbred (50% Hampshire × 50% local) pigs under the agro-climatic condition of Assam State, India. The experiment was also aimed to study the role of different level of energy ration (110, 100, and 90% energy of NRC feeding standard for pig) in variation of physiological and biochemical parameters in two genetic groups of pigs in different seasons. The metabolizable energy value were 3260, 2936.5, and 3585.8kcal/kg in grower ration and 3260.2, 2936.6, and 3587kcal/kg in finisher ration for normal energy (NE), low energy (LE) and high energy (HE), respectively. Both the genetic group of animals were housed separately under intensive system of management. Each pen was measuring 10' × 12' along with an outer enclosure. Six weaned piglets (almost similar body weight of average 10.55kg) of each group were kept in a separate pen. However, after attainment of 35kg body weight, the animals of a group were divided in two pens of three animals each. The present experiment indicated that average ambient temperature during summer months (27.33-29.51°C) was above the comfort zone for pigs (22°C). The significantly (P < 0.01) higher relative humidity (RH) (%) was recorded in outdoor environment (87.26-91.10%) and in the morning time (86.60-91.10%). The temperature humidity index (THI) during the study period was found to be indicative of thermal stress to the experimental animals during summer (79.55-82.56). Physiological parameters viz., respiration rate (RR) and rectal temperature (RT) were significantly (P < 0.01) higher in summer season (43.75-72.12 breaths/min. and 102.29-103.23°F) and non-significantly higher values were recorded in Hampshire pigs. It was also found that the significantly (P < 0.01) lower RR as well as RT was recorded in the pigs fed with high energy (HE) ration during summer season. Serum triiodothyronine (T3) and thyroxine (T4) concentrations were significantly (P < 0.01) lower during summer, while both the genetic groups showed significantly (P < 0.01) higher concentration of serum cortisol during summer season. It was also observed that thyroid hormone and cortisol concentrations were maintained in groups of pig fed vegetable oil incorporated HE diet during summer. From the present study, it is found that the increasing the energy level of the ration might be helpful to minimize the effects of thermal stress during summer.

A cross sectional study of urinary phthalates, phenols and perchlorate on thyroid hormones in US adults using structural equation models (NHANES 2007–2008)

BackgroundBiomonitoring data shows that people are exposed to phthalates, phenols and perchlorates. Many of these compounds are endocrine disrupting compounds that affect thyroid hormone levels. Yet the effect of these compounds on thyroid hormone levels are often evaluated individually rather than as a mixture. Our objective was to examine the association between 11 urinary endocrine disrupting compounds and thyroid hormones using structural equation models. MethodsUsing data from the National Health and Nutrition and Examination Survey 2007–2008, we fit a latent variable utilizing urinary measurements of 9 compounds in females (perchlorate, bisphenol A, benzophenone-3, mono-2ethyl5carboxypentyl phthalate, mono-n-butyl phthalate, mono-(3-carboxypropyl) phthalate, mono(2ethyl5hydroxyhexyl) phthalate, mono-benzyl phthalate, and mono-isobutyl phthalate) and 8 compounds in males (without benzophenone-3). The association of the latent variable with serum thyroid hormones (Total T3, Total T4, and Thyroid Stimulating Hormones) was assessed in females (N = 710) and males (N = 850) over the age of 12 controlling for age, race, and urinary creatinine. ResultsIn males, urinary endocrine disrupting compound levels were negatively associated with thyroxine (β: −0.19, 95% Confidence Interval (95% CI): −0.31, −0.05). In females, urinary endocrine disrupting compound levels were positively associated with triiodothyronine serum concentrations (β: 0.09, 95% CI: −0.03, 0.21) however this association was not statistically significant. ConclusionsThis cross-sectional analysis provides additional evidence that environmental exposure to phthalates and phenols is associated with endocrine-related processes. Furthermore, these results suggested sex-specific differences in exposure to endocrine disrupting mixtures, and the exposure-response between endocrine disrupting mixtures and thyroid hormone levels. Specifically, higher exposure to a mixture of endocrine disrupting compounds was associated with lower levels of total T4 in males but not in females. While a structural methodological framework was used to assess these complex relationships, the cross sectional nature of this analysis limits causal inference and further research is needed to determine the clinical significance of these findings.

Association between genetic polymorphism and levothyroxine bioavailability in hypothyroid patients.

Thyroid hormones play a vital role in the human body for growth and differentiation, regulation of energy metabolism, and physiological function. Hypothyroidism is a common endocrine disorder, which generally results from diminished normal circulating concentrations of serum thyroxine (fT4) and triiodothyronine (fT3). The primary choice in hypothyroidism treatment is oral administration of levothyroxine (L-T4), a synthetic T4 hormone, as approximately 100-125 μg/day. Generally, dose adjustment is made by trial and error approach. However, there are several factors which might influence bioavailability of L-T4 treatment. Genetic background could be an important factor in hypothyroid patients as well as age, gender, concurrent medications and patient compliance. The concentration of thyroid hormones in tissue is regulated by both deiodinases enzyme and thyroid hormone transporters. In the present study, it was aimed to evaluate the effects of genetic differences in the proteins and enzymes (DIO1, DIO2, TSHR, THR and UGT) which are efficient in thyroid hormone metabolism and bioavailability of L-T4 in Turkish population. According to our findings, rs225014 and rs225015 variants in DIO2, which catalyses the conversion of thyroxine (pro-hormone) to the active thyroid hormone, were associated with TSH levels. It should be given lower dose to the patients with rs225014 TT and rs225015 GG genotypes in order to provide proper treatment with higher effectivity and lower toxicity.

Correlation between thyroid hormones and body weight in hypothyroid females in Erbil city

Hypothyroidism, also known as underactive thyroid, is a condition where the thyroid gland does not produce enough of thyroid hormone called thyroxine. Thyroid hormones regulate the way in which the body uses energy - metabolism - and without enough thyroxine, many of the body's functions slow down. Through this study we aim to define any relationship of fluctuations that might exist between serum thyroid stimulating hormone, triiodothyronine and its prohormone thyroxine with body weight in hypothyroidism under thyroxin therapy. The present cross-sectional study deals with estimation of levels of serum thyroid stimulating hormone, triiodothyronine, thyroxine, Vitamin D 3 and calcium in (100) patients with hypothyroidism, all the biochemical parameters were estimated calorimetrically. The mean ± SE concentrations of serum thyroid stimulating hormone, triiodothyronine, thyroxine, Vitamin D and Calcium were 33.6 ± 1.3 UIU/ml, 10.6 ±1.1 nmole/L, 41.1 ±1.4 nmole/L, 29.5 ± 2.3 nmole/L and 13.4 ± 2.1 mg/dl, respectively. In the existing study we found, a statistical positive correlation (r = 0.404 ) between thyroid stimulating hormone and body weight. While there were a negative correlation between triiodothyronine (r = -0,41538 ), thyroxine (r = -0,41538 ) and body weight. Our results of the present study demonstrates that weight gain and obesity are two common manifestation of hypothyroidism.

Acute nitrite exposure alters the metabolism of thyroid hormones in grass carp (Ctenopharyngodon idellus)

Nitrite has the potential to disturb thyroid hormone homeostasis, but little is known about the underlying mechanisms. In the present study, juvenile grass carp (Ctenopharyngodon idellus) were exposed to various concentrations of nitrite (0, 0.5, 1, 4, and 16 mg/L, respectively). Serum concentrations of triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4), 3,3,5ʹ-triiodothyronine (rT3), thyroid-stimulating hormone (TSH), and the activity of iodothyronine deiodinases were assayed at 0, 12, 24, 48, and 96 h after exposure. It was found that acute nitrite exposure significantly altered the TH levels and iodothyronine deiodinase activities. The rT3 levels were significantly increased in the treatment groups, whereas the concentrations of T3, FT3, FT4, and TSH decreased significantly. The concentration of T4 was elevated in the lower-dose exposure group, but was reduced in the higher-dose exposure group. Increases in type I iodothyronine deiodinase (ID1) and type III iodothyronine deiodinase (ID3) activities were observed in the exposure groups. The activity of type II iodothyronine deiodinase (ID2) decreased at 12 and 24 h after exposure. A decrease of colloid in the thyroid follicles was observed in the exposure group. The results indicate that acute nitrite exposure has the potential to disturb the homeostasis of thyroid hormone metabolism, leading to a hypothyroidism state in the juvenile grass carp.

Effects of hyper- and hypothyroidism on the development and proliferation of testicular cells in prepubertal rats.

Thyroid hormones are important in the development and regulation of testes. This study was conducted to determine the effects of hyper- and hypothyroidism on testicular development in prepubertal rats aged 20-70days. Weaning male rats (20days old) until day 70 age were randomly divided into four groups: control, hyperthyroid (hyper-T), hypothyroid (hypo-T) and hypothyroid treated with thyroxine (T4) (hypo-T+T4). The results indicated that thyroid hormones caused a significant effect in body and testis weights, and food and water consumption. In addition there were changes in serum concentrations of tri-iodothyronine, T4, thyroid stimulating hormone (TSH) and testosterone. Histomorphology showed a significant decrease in seminiferous tubule diameter in hyper-T compared to the other groups. Leydig cell numbers showed a significant elevation in hyper-T but not in hypo-T groups. Immunostaining indicated that TSH receptor (TSHR), thyroid hormone receptors α/β (TRαβ) and proliferating cell nuclear antigen (PCNA) have the roles in testicular development. Our findings suggest that hyper- and hypo-thyroidism regulate testicular cell proliferation and spermatogenesis in prepubertal rats, indicating that expression of TSHR, TRαβ and PCNA may be regulated by thyroid hormones that are involved in testicular development; and that the administration of T4 to the hypo-T+T4 group leads to an improvement in the testicular condition.

Simultaneous determination of polychlorinated biphenyls and organochlorine pesticides in fish tissue using QuEChERS method

Nitrite has the potential to disturb thyroid hormone homeostasis, but little is known about the underlying mechanisms. In the present study, juvenile grass carp (Ctenopharyngodon idellus) were exposed to various concentrations of nitrite (0, 0.5, 1, 4, and 16 mg/L, respectively). Serum concentrations of triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), free thyroxine (FT4), 3,3,5ʹ-triiodothyronine (rT3), thyroid-stimulating hormone (TSH), and the activity of iodothyronine deiodinases were assayed at 0, 12, 24, 48, and 96 h after exposure. It was found that acute nitrite exposure significantly altered the TH levels and iodothyronine deiodinase activities. The rT3 levels were significantly increased in the treatment groups, whereas the concentrations of T3, FT3, FT4, and TSH decreased significantly. The concentration of T4 was elevated in the lower-dose exposure group, but was reduced in the higher-dose exposure group. Increases in type I iodothyronine deiodinase (ID1) and type III iodothyronine deiodinase (ID3) activities were observed in the exposure groups. The activity of type II iodothyronine deiodinase (ID2) decreased at 12 and 24 h after exposure. A decrease of colloid in the thyroid follicles was observed in the exposure group. The results indicate that acute nitrite exposure has the potential to disturb the homeostasis of thyroid hormone metabolism, leading to a hypothyroidism state in the juvenile grass carp.

Comparison of serum triiodothyronine, tetraiodothyronine and thyroid stimulating hormone concentrations in pregnant and lactating Beetal-cross and native goats in Garmsar township

BACKGROUND: The preliminary survey made about congenital goiter in goats in Garmsar township indicated that the disease occurs much more in Beetal-cross than native goats raised in the same area. OBJECTIVES: The aim of the present study was to compare of serum triiodothyronine (T3), tetraiodothyronine (T4) and thyroid stimulating hormone concentrations in pregnant and lactating Beetal-cross and native goats in Garmsar township. METHODS: One hundred Beetal-cross (n=50) and native (n=50) does in 4 groups (25 pregnant Beetal-cross, 25 lactating Beetal-cross, 25 pregnant native and 25 lactating native) were used in this study. Blood samples were obtained via jugular venipuncture and analyzed for serum T3, T4 and TSH concentrations. RESULTS: Breed had a significant (P<0.05) effect on T4 concentration and pregnancy had a significant (P<0.05) effect on T3 and TSH concentrations. No significant differences were seen for serum T3, T4 and TSH concentrations between pregnant and lactating native does. However, in the pregnant Beetal-cross, serum T3 and T4 concentrations were lower (P<0.05) and TSH concentration was higher (P<0.05) than lactating Beetal-cross does. CONCLUSIONS: The results of the present study highlight the relationships between thyroid activity and breed in the goat species that may play a role in more occurrence of congenital goiter in Beetal-cross in Garmsar township.