Decreased Thyroid Hormone Levels Research Articles

Indications for Intravenous T3 and T4.

Therapy with thyroid hormones normally is restricted to substitution therapy of patients with primary or secondary hypothyroidism. Typically, thyroid hormones are given orally. There are few indications for intravenous use of thyroid hormones. Indications for parenteral application are insufficient resorption of oral medications due to alterations of the gastrointestinal tract, partial or total loss of consciousness, sedation in the intensive care unit or shock. In almost all cases levothyroxine is the therapy of choice including congenital hypothyroidism. In preterm infants with an altered thyroid hormone status studies with thyroid hormones including intravenous liothyronine showed a normalisation of T3 levels and in some cases an amelioration of parameters of ventilation. A benefit for mortality or later morbidity could not be seen. Effects on neurological improvements later in life are under discussion. Decreased thyroid hormone levels are often found after cardiac surgery in infants and adults. Intravenous therapy with thyroid hormones improves the cardiac index, but in all other parameters investigated, no substantial effect on morbidity and mortality could be demonstrated. Oral liothyronine therapy in these situations was equivalent to an intravenous route of application. In myxedema coma intravenous levothyroxine is given for 3 to 10 days until the patient can take oral medication and normal resorption in the gastrointestinal tract is achieved by restoring at least peripheral euthyroidism. Intravenous levothyroxine is the standard in treating patients with myxedema coma. A protective effect on the heart of i.v. levothyroxine in brain-dead organ donors may be possible.

Effects of Cadmium and Nickel on Embryonic Development of Fish: A Review

In fish embryos, a variety of abnormalities have been found, including stunted growth, a reduced survival rate, and aberrant development. One plausible explanation is that early embryonic stages are more sensitive. Embryonic studies provide additional information regarding the various impacts of heavy metals on fish, but information on larval abnormalities caused by waterborne metals is lacking. It is found that cadmium (Cd) causes a decrease in thyroid hormone levels as well as a disruption in fish growth hormone expression. Similarly, negative health effects have been documented as a result of nickel (Ni) exposure. Some toxic effects on organs, skin irritation, skin itches or blisters and allergic reactions may occur as a result of Ni exposure. This review study focuses on the impacts of Cd and Ni, on the embryonic development of different fish species. The evidence on abnormalities in fish larvae caused by Cd and Ni was also provided in text.

Perfluorooctanoic acid disrupts thyroid-specific genes expression and regulation via the TSH-TSHR signaling pathway in thyroid cells

Perfluorooctanoic acid (PFOA) is a highly persistent and widespread chemical in the environment with endocrine disruption effects. Although it has been reported that PFOA can affect multiple aspects of thyroid function, the exact mechanism by which it reduces thyroxine levels has not yet been elucidated. In this study, FRTL-5 rat thyroid follicular cells were used as a model to study the toxicity of PFOA to the genes related to thyroid hormone synthesis and their regulatory network. Our results reveal that PFOA interfered with the phosphorylation of the cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB) induced by thyroid-stimulating hormone (TSH), as well as the transcription levels of paired box 8 (PAX8), thyroid transcription factor 1 (TTF1), sodium/iodide cotransporter (NIS), thyroglobulin (TG), and thyroid peroxidase (TPO). However, the above outcomes can be alleviated by enhancing cAMP production with forskolin treatment. Further investigations showed that PFOA reduced the mRNA level of TSH receptor (TSHR) and impaired its N-glycosylation, suggesting that PFOA has disrupting effects on both transcriptional regulation and post-translational regulation. In addition, PFOA increased endoplasmic reticulum (ER) stress and decreased ER mass in FRTL-5 cells. Based on these findings, it can be inferred that PFOA disrupts the TSH-activated cAMP signaling pathway by inhibiting TSHR expression and its N-glycosylation. We propose that this mechanism may contribute to the decrease in thyroid hormone levels caused by PFOA. Our study sheds light on the molecular mechanism by which PFOA can disrupt thyroid function and provides new insights and potential targets for interventions to counteract the disruptive effects of PFOA.

The frequency of thyroid dysfunction in patients with a diagnosis of depressive disorder.

Thyroid dysfunctions are among the most common endocrine disorders in society. An increase or decrease in thyroid hormone levels may present with neurological and/or psychiatric symptoms. In this study, we aimed both to determine the prevalence of this disorder in our region by determining the frequency of thyroid dysfunction in patients diagnosed with major depressive disorder in our outpatient clinic and to raise awareness during the evaluation process of patients. Thyroid-stimulating hormone (TSH) levels of 1035 patients diagnosed with major depressive disorder in our hospital between January 2020 and January 2022 were retrospectively scanned from the hospital information management system and those outside the reference ranges (0.38-5.33 mIU/L) were determined. It was observed that TSH was not within the reference ranges in approximately 7% of the patients diagnosed with depressive disorder. 1035 patients were included in the study. When the blood results of 1035 patients included in the study were examined retrospectively, 32 of them had TSH values below 0.38 mIU/L. TSH value was found to be above 5.33 mIU/L in 44 of them. Obtained data have shown that thyroid dysfunctions can be encountered frequently in patients presenting with depressive complaints. It is thought that the evaluation of patients with depressive complaints in terms of thyroid dysfunction, and the treatment of the underlying thyroid dysfunction will contribute to the regression of psychiatric symptoms.

Thyroid hormone decreasing after mechanical thrombectomy for cerebral infarction (P3-5.018)

<h3>Objective:</h3> The aim of this study wasto clarify the changes in thyroid hormone levels in the acute phase and the effects of the iodine contrast agent on thesehormones. <h3>Background:</h3> Mechanical thrombectomy (MT) is an established treatment for large vessel occlusion in patients with cerebral infarction. The use of iodine contrast agent decreases thyroid hormone levels via the so-called Wolff-Chaikoff effect. Low triiodothyronine (T3) syndrome caused by a severe illness status can contribute to decreased thyroid hormones. Reportedly, a low T3 level is associated with poor prognosis in patients with cerebral infarction. <h3>Design/Methods:</h3> This was a single-center, prospective, and single-arm trial. Thyroid stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) were tested on admission and 24 h postoperatively in patients who were approved for MT. <h3>Results:</h3> A total of 37 patients were screened during the study period and 31 patients were enrolled. Significant decreases were observed in TSH (<i>P</i> &lt; 0.001) and FT3 (<i>P</i> &lt; 0.001) levels 24 h after MT. Moreover, there was a correlation between the decrease ratio of change in FT3 levels and the amount of iodine contrast agent used per body surface area (<i>r</i> = 0.43, <i>P</i> = 0.019), while no such correlations were detected for TSH and FT4. <h3>Conclusions:</h3> We demonstrated that decrease in TSH and FT3 levels in the acute phase after MT and that FT3 levels were associated with the amount of iodine contrast agent used. <b>Disclosure:</b> Dr. Kobayashi has nothing to disclose.

Cardiovascular Complications of Hyperthyroidism

Thyrotoxicosis is a clinical syndrome caused by an excess of thyroid hormones circulating in the body. Myocardium and blood arteries have thyroid hormone receptors; hence, an increase or decrease in thyroid hormone levels can alter cardiovascular function. Cardiovascular complications are obvious in-patient with hyperthyroidism. Palpitations, tachycardia, exercise intolerance, dyspnea with exertion, expanded pulse pressure, and on occasion atrial fibrillation are associated with hyperthyroidism, excessive endogenous thyroid hormone production, and thyrotoxicosis, the condition caused by excess thyroid hormone. In the early stages of hyperthyroidism, a high cardiac output and hypertrophy of the left ventricle are observed, followed by biventricular dilatation and congestive heart failure. Atrial fibrillation and pulmonary arterial hypertension can contribute to the higher morbidity associated with untreated hyperthyroidism. Therefore, early and effective treatment of hyperthyroidism is required to prevent thyrotoxic cardiomyopathy.

Pesticides Exposure and Thyroid Hormone Levels Among Agricultural Workers and Pesticide Applicators: A Systematic Review

Introduction: Presently, the global consumption of pesticides including insecticides, herbicides, and fungicides to protect crops is increasing. Pesticides' role as Endocrine-Disrupting Chemicals (EDCs) has gained great concern in the field of thyroid hormones. Therefore, this systematic review aimed to determine the link of pesticide exposure with thyroid hormone levels among male agricultural workers and pesticide applicators. Discussion: It was discovered that the majority of reviewed articles have similar results concerning the effects of pesticide exposure on the serum levels of thyroid hormones among either farmworkers or pesticide applicators. Commonly, insecticides, herbicides, and fungicides are known as one of the EDCs. The results showed the elevation of TSH and T4 serum levels mostly occurred among groups exposed to insecticide application only rather than those exposed to various pesticide types. Moreover, the hormonal change differed based on each class of pesticide. Conclusion: This review suggests that some types of pesticides extensively used in agriculture might be involved in the increase and decrease in thyroid hormone levels among exposed individuals. Further studies should assess specific types of pesticides and the adverse health effects which involve confounding factors to yield robust analysis.

ACR Statement on Use of Iodinated Contrast Material for Medical Imaging in Young Children and Need for Thyroid Monitoring.

In a March 2022 drug safety communication, the FDA issued guidance recommending that children “through three years old” be monitored for the possibility of hypothyroidism or a temporary decrease in thyroid hormone levels within 3 weeks of exposure to intravascular iodine-containing (iodinated) contrast material (ICM).

MRNA-miRNA sequencing reveals mechanisms of 2,2'-dipyridyl disulfide-induced thyroid disruption in Japanese flounder (Paralichthys olivaceus).

This study was conducted to evaluate the thyroid-disrupting effects of 2,2'-dipyridyl disulfide using Japanese flounder (Paralichthys olivaceus) as an animal model and to reveal the underlying mechanisms from the perspective of miRNA-mRNA interactions. The results indicated that 2,2'-dipyridyl disulfide exposure decelerated the metamorphic progress of P. olivaceus, suggesting its thyroid-disrupting property as an antagonist. Furthermore, radioimmunoassays, thyroid histological observation, real-time polymerase chain reaction, and mRNA sequencing showed that 2,2'-dipyridyl disulfide exposure exerted its thyroid-disrupting effects on larval and juvenile P. olivaceus by targeting multiple processes and pathways involved in the thyroid system, including peripheral metabolism of thyroid hormones, the thyroid hormone synthesis pathway, and the thyroid hormone/thyroid hormone receptor signaling pathway. In particular, global upregulation of the gene expression of three deiodinases caused decreases in thyroid hormone levels after 2,2'-dipyridyl disulfide exposure that are believed to be responsible for the inhibition of metamorphosis in P. olivaceus. Finally, miRNA sequencing suggested that several evolutionarily conserved miRNAs play important roles in the mechanism of 2,2'-dipyridyl disulfide-induced thyroid disruption. Specifically, overexpression of pny-miR-723a and pny-miR-216a resulted in upregulation of deiodinase 1 mRNA levels in the 2,2'-dipyridyl disulfide exposure group. This study provides the first evidence that 2,2'-dipyridyl disulfide has thyroid-disrupting properties and is also the first study remarking on the roles of miRNA-mRNA interactions in the action mechanisms of thyroid disruptors.

Thyroid hormone decreasing after mechanical thrombectomy for cerebral infarction

ObjectiveMechanical thrombectomy (MT) is an established treatment for large vessel occlusion in patients with cerebral infarction. The use of iodine contrast agent decreases thyroid hormone levels via the Wolff−Chaikoff effect. Low triiodothyronine (T3) syndrome caused due to severe illness status can contribute to decreased levels of thyroid hormones. Reportedly, a low T3 level is associated with poor prognosis in patients with cerebral infarction. This study aimed to clarify the changes in thyroid hormone levels in the acute phase after MT and the effects of the iodine contrast agent on these hormones. MethodsThis was a single-center, prospective, and single-arm trial. Thyroid stimulating hormone (TSH), free T3 (FT3), and free T4 (FT4) levels were tested on admission and 24 h postoperatively in patients who were approved for MT. ResultsA total of 37 patients were screened during the study period and 31 patients were enrolled in this study. Significant decreases were observed in TSH (P < 0.001) and FT3 (P < 0.001) levels 24 h after MT. Moreover, there was a correlation between the decrease in ratio of change in FT3 levels and the amount of iodine contrast agent used per body surface area (r = 0.43, P = 0.019), while no such correlations were detected for TSH and FT4. ConclusionWe demonstrated that TSH and FT3 levels decreased in the acute phase after MT and that FT3 levels were associated with the amount of iodine contrast agent used.

Environmental Factors Affecting Thyroid-Stimulating Hormone and Thyroid Hormone Levels.

Thyroid hormones are necessary for the normal functioning of physiological systems. Therefore, knowledge of any factor (whether genetic, environmental or intrinsic) that alters the levels of thyroid-stimulating hormone (TSH) and thyroid hormones is crucial. Genetic factors contribute up to 65% of interindividual variations in TSH and thyroid hormone levels, but many environmental factors can also affect thyroid function. This review discusses studies that have analyzed the impact of environmental factors on TSH and thyroid hormone levels in healthy adults. We included lifestyle factors (smoking, alcohol consumption, diet and exercise) and pollutants (chemicals and heavy metals). Many inconsistencies in the results have been observed between studies, making it difficult to draw a general conclusion about how a particular environmental factor influences TSH and thyroid hormone levels. However, lifestyle factors that showed the clearest association with TSH and thyroid hormones were smoking, body mass index (BMI) and iodine (micronutrient taken from the diet). Smoking mainly led to a decrease in TSH levels and an increase in triiodothyronine (T3) and thyroxine (T4) levels, while BMI levels were positively correlated with TSH and free T3 levels. Excess iodine led to an increase in TSH levels and a decrease in thyroid hormone levels. Among the pollutants analyzed, most studies observed a decrease in thyroid hormone levels after exposure to perchlorate. Future studies should continue to analyze the impact of environmental factors on thyroid function as they could contribute to understanding the complex background of gene–environment interactions underlying the pathology of thyroid diseases.

An unusual case of struma ovarii.

IntroductionStruma ovarii is a teratoma of the ovaries predominantly composed of thyroid tissue. Hyperthyroidism associated with struma ovarii is rare, occurring in approximately 8% of cases. Due to the rarity of struma ovarii, available data are limited to case reports and small case series.Methods and resultsWe report on a 61-year-old female patient with known Hashimoto’s thyroiditis on levothyroxine replacement therapy for years with transition to clinical and biochemical hyperthyroidism despite antithyroid medication with carbimazole (10 mg/day), new diagnosis of urothelial carcinoma and an adnexal mass suspicious of ovarian cancer. The patient underwent resection of the adnexal mass and histopathology revealed a mature teratoma predominantly composed of thyroid tissue showing high levels of sodium iodide symporter protein expression. Following struma ovarii resection and disappearance of autonomous production of thyroid hormones, the patient developed hypothyroidism with severely decreased thyroid hormone levels fT4 and fT3 (fT4 0.4 ng/dL, reference interval 0.9–1.7 and fT3 < 1.0 pg/mL, reference interval 2.0–4.4). This has previously been masked by continued thyroid-stimulating hormone suppression due to long-term hyperthyroidism pre-surgery indicating secondary hypothyroidism, in addition to primary hypothyroidism based on the known co-existing chronic lymphocytic thyroiditis of the orthotopic thyroid gland. Levothyroxine administration was started immediately restoring euthyroidism.ConclusionThis case illustrates possible diagnostic pitfalls in a patient with two concurrent causes of abnormal thyroid function.Learning pointsStruma ovarii is an ovarian tumor containing either entirely or predominantly thyroid tissue and accounts for approximately 5% of all ovarian teratomas.In rare cases, both benign and malignant struma ovarii can secrete thyroid hormones, causing clinical and biochemical features of hyperthyroidism.Biochemical features of patients with struma ovarii and hyperthyroidism are similar to those of patients with primary hyperthyroidism. In such cases, thyroid scintigraphy should reveal low or absent radioiodine uptake in the thyroid gland, but the presence of radioiodine uptake in the pelvis in a whole body radioiodine scintigraphy.We give advice on possible diagnostic pitfalls in a case with two simultaneous causes of abnormal thyroid function due to the co-existence of struma ovarii.

Management of Cardiogenic Shock due to Thyrotoxicosis: A Systematic Literature Review.

Background A grave complication of thyrotoxicosis, or thyroid storm, is the development of heart failure and cardiomyopathy. Recognizing this condition is imperative in preventing further left ventricular dysfunction and cardiogenic shock. This manuscript aims to review the literature on cardiogenic shock associated with thyrotoxicosis and present management recommendations on this rare condition.Methods A literature search was performed in December of 2018, using the PubMed medical search engine. A systematic search was carried out using the keywords Thyroid Storm AND Cardiogenic Shock and Thyrotoxicosis AND Shock.Management Decrease of thyroid hormone levels using therapeutic plasma exchange LV Unloading and ventilation by Impella and Extracorporeal Mechanical Ventilation (ECMO).Conclusion Patients presenting with thyroid storm-induced shock may not be suitable candidates for traditional management with β-adrenergic blockers (β-blockers). The use of β-blockers could exasperate their condition. Through extensive literature review on this rare condition, the most effective management was found to be therapeutic plasma exchange in order to decrease thyroid hormone levels, which have direct toxic effect on the heart. Furthermore, the use of ECMO and Impella is advised to reduce pressure on the heart and ensure the patient’s organs are well oxygenated and perfused while the left ventricle is recovering.

Cardioprotection by triiodothyronine following caloric restriction via long noncoding RNAs

Severe caloric-restriction compromises thyroid hormone (TH) status, apparently to save energy and proteins for enduring stress stimulus. However, a persistent decrease in TH levels may compromise heart function. We hypothesized that supplementation of low dose active TH or targeting hypoxia-inducible factor-1-alpha, HIF-1α (a strong activator of deiodinase enzyme that degrades peripheral active THs) will prevent deterioration of cardiac performance. Adult mice were subjected to acute fasting based on institutional animal protocols with ad libitum access to water. The following groups were studied: Control mice with free access to food; severe caloric restriction fasting only group; Fasting with Triiodo-l-Thyronine (T3); Fasting with HIF-1α inhibitor (BAY). Cardiac hemodynamic and electrophysiological studies were performed and role of long noncoding RNAs were explored. Following severe caloric-restriction, we found that body weights, and heart weights to a partial extent, were decreased. Low-dose T3 treatment attenuated left ventricular hemodynamic impairment in indices of cardiac contractility and relaxation. In electrophysiology studies, fasting mice developed atrial tachyarrhythmias upon induction. This reverted to control levels following T3 treatment. There was a significant increase in atrioventricular conduction time and significant decrease in heart rate following fasting. Both these changes were attenuated following T3 treatment. Furthermore, BAY partially improved hemodynamics. Compared to the severe caloric-restriction group, both T3 and BAY reduced MALAT1 and GAS5 long noncoding RNA expression. These new findings indicate that T3 and BAY protect from cardiac decompensation secondary to acute severe caloric-restriction partly mediated by long noncoding RNAs.

Role of Total Thyroidectomy in Painful (Symptomatic) Hashimoto's Thyroiditis: Descriptive Study.

Hakura Hashimoto described Hashimoto's Thyroiditis (HT) in 1912. In HT, there occurs formation of antibodies against the self (thyroid), which causes enlargement of the thyroid gland as a whole and decreased thyroid hormone levels. Most of the patients with HT are given medical line of management (hypo/hyperthyroidism). The indications for surgical line of management for HT are due to pressure symptoms over the trachea and oesophagus, pain in the thyroid gland and for chance of malignancy. Surgical treatment gives complete relief from pain and pressure symptoms and also prevents the risk of malignancy. To evaluate the outcome and complications of total thyroidectomy in painful (symptomatic) Hashimoto's thyroiditis. It was a Hospital based Descriptive study conducted in tertiary care teaching hospital by ENT Department, Sri Manakula Vinayagar Medical College and Hospital, Pondicherry from Nov 2017 to May 2019. Sample size was 30. All patients with symptomatic (painful) HT was given trail of medical therapy (steroids and NSAIDS), following repeated attempts of failed medical therapy, surgical management (total thyroidectomy) was preferred. Visual Analog Scale (VAS) was used to assess the pain grading pre and post operatively. MS Excel and SPSS trial version 20 software was used to analyze the data. The Wilcoxan Signed Ranked test was used as test of significance to identify the difference between ordinal variables. In this study, all the 30 patients had pain as the predominant symptom. Visual Analog Scale was used to grade the pain in all the patients preoperatively and 2weeks postoperatively. All the patients had significant reduction in the pain following total thyroidectomy, when compared to pre-operative VAS grading. Total thyroidectomy is the technique of choice in surgical treatment of symptomatic Hashimoto's thyroiditis (pain, tenderness and pressure symptoms) which warrants a radical and definitive control of the disease, without any risk of relapse and without the side effects of medical management. Moreover in longstanding cases of HT, the risk of malignant transformation is prevented due to total thyroidectomy. In experienced hands it assures total relief of compressive and painful symptoms and low incidence of/nil major complications.

The Effects of Aerobic Exercise on Thyroid Hormone Levels in Obese Boys

Aim: Although beneficial effects of physical exercises on adulthood obesity are well known, it is unclear how physical exercises affect thyroid hormone related body composition, basal metabolic rate and thermogenesis in obese children. Our objective is to examine the effects of physical exercise program on 3-5-3’triiodothyronine (T3) and 3-5-3’-5’tetraiodothyronine (T4) in obese boys. Materials and Method: Our study consisted of 10 obese boys (aged from 13 to 15) and a control group of 10 healthy boys age and gender matched. Before exercise program, 10 ml blood samples were taken from the obese and control group boys; and 10 ml blood samples were taken from the obese boys after program exercise 3 days/week for 12 weeks. The lipid profiles, creatine kinase (CK), creatine kinase-MB, T3 and T4 levels in blood samples were measured for both groups. Results: In present study, it was found that control group and obese boys after aerobic exercise had significantly higher T3 and T4 levels (1.63±0.17; 9.80±0.93 and 1.70±0.10; 10.1±0.54, respectively) and significantly lower CK levels (142.7±4.11 and 151.8±3.70, respectively) than those of obese boys before aerobic exercise (1.19±0.81; 7.37±0.47 and 165.3±2.49, respectively). Furthermore, it was found that aerobic exercise significantly decreased triglyceride and cholesterol levels in obese boys (104.0±3.77 and 193.7±2.90, respectively). Conclusion: When these findings are taken into account, it may be suggested that aerobic exercises can help with the improvement of decreased thyroid hormone levels which may be cause a weight increase together with a decrease in basal metabolic rate and thermogenesis in obese boys.

2978 Hypothyroidism Is Associated With Lower Mortality in Hospitalized Patients With Cirrhosis

INTRODUCTION: The liver is involved in the synthesis of thyroid binding proteins, the peripheral conversion of T4 to T3, and thyroid hormone conjugation and excretion. Consequently, liver dysfunction is associated with a decrease in thyroid hormone levels. Previous studies have supported thyroid hormone levels to have a predictive role for survival in critically ill patients. Here, we seek to evaluate if hypothyroidism influences survival in hospitalized patients with cirrhosis. METHODS: The National Inpatient Sample (NIS) is an inpatient database comprising approximately 20% of all inpatient admissions to hospitals in the United States. From the database, we collected data from hospitalized patients with cirrhosis listed as primary or secondary diagnosis and divided them into two subgroups: those with a diagnosis of hypothyroidism and those without. We reviewed and compared the two groups for mean hospital length of stay in days, Charlson comorbidity index as well as rates in mortality. IBM Statistical Package for the Social Sciences (SPSS) was used for statistical analysis. RESULTS: A total of 338, 990 cases of patients from the 2012-2014 NIS database had cirrhosis as primary or secondary diagnosis. 35,135 of these patients (10.36%) had hypothyroidism. The mean length of hospital stay in patients with cirrhosis and hypothyroidism was 5.1 days and 4.9 days for those without hypothyroidism. Charlson comorbidity index was significantly higher (P &lt; 0.05) in cirrhotic patients with hypothyroidism. In the patients with cirrhosis, the mortality was 4%. In the subgroup with hypothyroidism, the mortality was 3.2% while the other subgroup without hypothyroidism was 4.1%. After adjusted for age, sex, race, and the Charlson comorbidity index, the group of patients with hypothyroidism had lower mortality (OR: 0.74, 95% CI (0.7-0.8). CONCLUSION: Our results show that cirrhotic patients with hypothyroidism had a higher comorbidity but a lower rate of mortality in the hospital than those without hypothyroidism. A review of the literature showed no consensus of suppressed total thyroid hormone level and its association with mortality. Some studies demonstrate that lower fT3 levels are directly associated with severity of liver disease and that lower fT3 was associated with higher mortality risk in the ICU setting. Further studies should be done to explore this association.

Urinary 3-phenoxybenzoic acid levels and the association with thyroid hormones in adults: Korean National Environmental Health Survey 2012–2014

BackgroundOwing to insecticidal activity at low doses with relatively low toxicity in humans, synthetic pyrethroids have been used widely for pest control in agricultural and domestic settings. Pyrethroids are suspected for potential endocrine disruption. However, the thyroid disrupting effects of pyrethroids, particularly in humans, is relatively underexplored. ObjectivesThis study aimed to report 3-phenoxybenzoic acid (3-PBA) concentrations in urine, and assess its association with serum thyroid hormone (TH) levels in a representative adult population of Korea. MethodsData obtained from representative Korean adults recruited in the Korean National Environmental Health Survey (2nd round, 2012–2014) were analyzed. Urinary 3-PBA levels were associated with serum thyroxine (T4), total triiodothyronine (T3), and thyroid-stimulating hormone (TSH) levels among the Korean adult population. ResultsUrinary 3-PBA levels among Korean adults were >3 times higher than those reported in Canada and the United States. Urinary 3-PBA levels showed negative association with serum T4, and this pattern was not changed after stratification by sex. For T3, the association varied by sex and exposure levels. Male demonstrated the same inverse association between urinary 3-PBA and T3, but female did not show such association. Among adults in the lower half of urinary 3-PBA levels, the association with T3 was significant, while that among the remainder was marginal. The association with T4 remained significant on sensitivity analysis, after controlling for other urinary chemicals. ConclusionUrinary 3-PBA levels in the general Korean adult population were found to be generally higher than those of other countries, and were associated with decreased TH levels. Considering the importance of THs, the public health implications of pyrethroid insecticide exposure warrant further studies.

Nineteenth-Century Homeopathic Materia Medica Texts Predict Source Materials Whose Physiological Actions Influence Thyroid Activity.

The homeopathic materia medica contains hundreds of thousands of observations collected over the course of two centuries. It includes both clinical observations of potentized medicines and observations of the actions of potentized medicines on healthy subjects (provings). This current study was undertaken to determine the degree to which observations within the materia medica were associated with the physiological mechanisms for thyroid activity-inhibiting substances in their undiluted state. Four specific symptoms for iodine deficiency were selected to describe the hypothyroid state: (1) generalized aggravation by or sensitivity to cold; (2) chronic painless hoarseness; (3) goiter; (4) painless diffuse non-scarring alopecia. Symptom representation for the four selected symptoms within the homeopathic materia medica was compared for 2 halogen inhibitors, for 3 substances that influence thyroid hormone target tissues, for 6 substances known or suspected to increase thyroid-stimulating hormone or decrease thyroid hormone levels, and for 11 substances not known to inhibit thyroid activity. To avoid knowledge bias, only those compilations of materia medica whose publication dates preceded the discoveries of crucial aspects of thyroid physiology were used as source materials for investigation. Homeopathic medicines derived from 11 substances with mechanisms for inhibition of thyroid activity were more likely to exhibit selected symptoms than the medicines derived from the 11 substances without known physiological mechanisms for thyroid activity inhibition. The difference between groups was analyzed via the Mann-Whitney non-parametric U test and was statistically significant to p < 0.01. After observations obtained from provings alone were removed from analysis, the difference remained significant to p < 0.01. Only the two halogen inhibitors of iodine (bromine and fluoric acid) and one of the influencers of thyroid hormone target tissue (calcium carbonate) were significantly goitrogenic. With respect to thyroid activity inhibition, there is a statistically significant association between observations recorded within the homeopathic materia medica and the expected physiological mechanisms for the corresponding undiluted substances.

Hypothalamus-pituitary-thyroid axis activity and function of cardiac muscle in energy deficit

Frequently repeated statement that energy restriction is a factor that improves cardiovascular system function seems to be not fully truth. Low energy intake modifies the hypothalamus-pituitary-thyroid axis activity and thyroid hormone peripheral metabolism. Thyroid hormones, as modulators of the expression and activity of many cardiomyocyte proteins, control heart function. Decreased thyroid hormone levels and their disturbanced conversion and action result in alternation of cardiac remodeling, disorder of calcium homeostasis and diminish myocardial contractility. This review provides a summary of the current state of knowledge about the mechanisms of energy restriction effects on thyroidal axis activity, thyroid hormone peripheral metabolism and action in target tissues, especially in cardiac myocytes. We also showed the existence of energy restriction-thyroid-heart pathway.