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Nutrients Dec 2023The literature on the connection between obesity, metabolic syndrome, and subclinical hypothyroidism is critically analyzed in this narrative review. These conditions... (Review)
Review
The literature on the connection between obesity, metabolic syndrome, and subclinical hypothyroidism is critically analyzed in this narrative review. These conditions are frequently observed among adult populations and various studies and meta-analyses have assessed their association. The prevalence of subclinical hypothyroidism in obese individuals is higher than in non-obese subjects and this trend is more pronounced in unhealthy obesity phenotypes. However, the diagnosis and treatment of subclinical hypothyroidism can be difficult in obese patients. Exaggerated body fat is linked to thyroid hypoechogenicity as evident through ultrasonography and euthyroid obese people have greater TSH, FT3, and FT3/FT4 ratios than non-obese individuals in a euthyroid condition. Moreover, a reduced expression of the TSH receptor and altered function of deiodinases has been found in the adipose tissue of obese patients. Current data do not support the necessity of a pharmacological correction of the isolated hyperthyrotropinemia in euthyroid obese patients because treatment with thyroid hormone does not significantly improve weight loss and the increase in serum TSH can be reversible after hypocaloric diet or bariatric surgery. On the other hand, obesity is linked to elevated leptin levels. Inflammation can raise the risk of Hashimoto thyroiditis, which increases the likelihood that obese patients will experience overt or subclinical hypothyroidism. Both metabolic syndrome and subclinical hypothyroidism are associated with atherosclerosis, liver and kidney disease. Hence, the association of these two illnesses may potentiate the adverse effects noted in each of them. Subclinical hypothyroidism should be identified in patients with obesity and treated with appropriate doses of L-thyroxine according to the lean body mass and body weight. Randomized controlled trials are necessary to verify whether treatment of thyroid deficiency could counteract the expected risks.
Topics: Adult; Humans; Obesity; Metabolic Syndrome; Diet, Reducing; Hypothyroidism; Thyrotropin
PubMed: 38201918
DOI: 10.3390/nu16010087 -
Journal of Veterinary Internal Medicine 2023Erroneous thyroid function test results can occur because of drugs that alter thyroid hormone physiology in one or more aspects, including synthesis, secretion,... (Review)
Review
Erroneous thyroid function test results can occur because of drugs that alter thyroid hormone physiology in one or more aspects, including synthesis, secretion, distribution, and metabolism. Research since publication of the last review in the Journal of Veterinary Internal Medicine (JVIM) 20 years ago has evaluated the effects of amiodarone, zonisamide, inhalant anesthetics, clomipramine, trilostane, and toceranib on thyroid function tests in the dog. In addition, recent work on the effects of glucocorticoids, sulfonamides, phenobarbital, and nonsteroidal anti-inflammatory drugs will be reviewed. Awareness of these effects is necessary to avoid misdiagnosis of hypothyroidism and unnecessary treatment.
Topics: Dogs; Animals; Thyroid Function Tests; Hypothyroidism; Thyroid Hormones; Amiodarone; Anti-Arrhythmia Agents; Dog Diseases
PubMed: 37498128
DOI: 10.1111/jvim.16823 -
Frontiers in Immunology 2023Though significant correlations between rheumatoid arthritis (RA) and hypothyroidism have been found in earlier observational studies, their underlying causal...
OBJECT
Though significant correlations between rheumatoid arthritis (RA) and hypothyroidism have been found in earlier observational studies, their underlying causal relationship is still unknown. Mendelian randomization (MR) was used in the current study to assess the bidirectional causation between RA and hypothyroidism.
METHOD
We gathered summary data from genome-wide association studies (GWASs) of RA and hypothyroidism in people of European descent. Then, using data from the FinnGen consortium, we replicated our findings. Three approaches were employed to assess the causal link between RA and hypothyroidism: MR-Egger, weighted median (WM), and inverse variance weighted (IVW). The pleiotropy and heterogeneity were examined using a variety of techniques, including the MR-Egger intercept, the MR-PRESSO approach, the leave-one-out method, and the Cochran's Q test.
RESULTS
The study looked at a bidirectional incidental relationship between RA and hypothyroidism. The risk of hypothyroidism increased with RA (IVW odds ratio (OR) = 1.28, 95% confidence interval (CI) = 1.18-1.39, = 8.30E-10), as did the risk of secondary hypothyroidism (IVW OR = 1.12, 95% CI = 1.05-1.21, = 9.64E-4). The results of reverse MR analysis revealed that hypothyroidism (IVW OR = 1.68, 95% CI = 1.51-1.88, = 4.87E-21) and secondary hypothyroidism (IVW OR = 1.74, 95% CI = 1.50-2.01, = 1.91E-13) were linked to an increased risk of RA. Additionally, we obtain the same results in the duplicated datasets as well, which makes our results even more reliable. This study revealed no evidence of horizontal pleiotropy.
CONCLUSION
The present study established a bidirectional causal link between RA and hypothyroidism. However, it differs slightly from the findings of prior observational studies, suggesting that future research should concentrate on the interaction mechanisms between RA and hypothyroidism.
Topics: Humans; Genome-Wide Association Study; Mendelian Randomization Analysis; Arthritis, Rheumatoid; Hypothyroidism; Nonoxynol
PubMed: 37600807
DOI: 10.3389/fimmu.2023.1146261 -
The Journal of Clinical Endocrinology... Nov 2023Many observational studies have reported on the association between educational attainment (EA) and thyroid function, but the causal relationship remains unclear.
CONTEXT
Many observational studies have reported on the association between educational attainment (EA) and thyroid function, but the causal relationship remains unclear.
OBJECTIVE
We aimed to obtain causal effects of EA on thyroid function and to quantify the mediating effects of modifiable risk factors.
METHODS
Two-sample mendelian randomization (MR) was performed by using summary statistics from large genome-wide association studies (GWAS) to assess the effect of EA on thyroid function, including hypothyroidism, hyperthyroidism, thyrotropin (TSH), and free thyroxine (FT4). A multivariable analysis was conducted to assess the mediating role of smoking and help to explain the association between EA and thyroid function. Similar analysis was further performed using data from the National Health and Nutrition Examination Survey (NHANES) 1999 to 2002.
RESULTS
In MR analysis, EA was causally associated with TSH (β = .046; 95% CI, 0.015-0.077; P = 4.00 × 10-3), rather than hypothyroidism, hyperthyroidism, and FT4. Importantly, smoking could serve as a mediator in the association between EA and TSH, in which the mediating proportion was estimated to be 10.38%. After adjusting for smoking in the multivariable MR analysis, the β value of EA on TSH was attenuated to 0.030 (95% CI, 0.016-0.045; P = 9.32 × 10-3). Multivariable logistic regression model in NHANES suggested a dose-response relationship between TSH (quartile [Q]4 vs Q1: odds ratio = 1.33; 95% CI, 1.05-1.68; P for trend = .023) and EA. Smoking, systolic blood pressure, and body mass index partially mediated the association between EA and TSH, with the proportion of the mediation effects being 43.82%, 12.28%, and 6.81%, respectively.
CONCLUSION
There is a potentially causal association between EA and TSH, which could be mediated by several risk factors, such as smoking.
Topics: Humans; Nutrition Surveys; Mendelian Randomization Analysis; Genome-Wide Association Study; Hypothyroidism; Thyrotropin; Hyperthyroidism; Educational Status; Polymorphism, Single Nucleotide
PubMed: 37285488
DOI: 10.1210/clinem/dgad344 -
International Journal of Molecular... Sep 2023The prevalence of hypothyroidism in patients with nonalcoholic fatty liver disease (NAFLD) is high (22.4%). Thyroid hormones (THs) regulate many metabolic activities in... (Review)
Review
The prevalence of hypothyroidism in patients with nonalcoholic fatty liver disease (NAFLD) is high (22.4%). Thyroid hormones (THs) regulate many metabolic activities in the liver by promoting the export and oxidation of lipids, as well as de novo lipogenesis. They also control hepatic insulin sensitivity and suppress hepatic gluconeogenesis. Because of its importance in lipid and carbohydrate metabolism, the involvement of thyroid dysfunction in the pathogenesis of NAFLD seems plausible. The mechanisms implicated in this relationship include high thyroid-stimulating hormone (TSH) levels, low TH levels, and chronic inflammation. The activity of the TH receptor (THR)-β in response to THs is essential in the pathogenesis of hypothyroidism-induced NAFLD. Therefore, an orally active selective liver THR-β agonist, Resmetirom (MGL-3196), was developed, and has been shown to reduce liver fat content, and as a secondary end point, to improve nonalcoholic steatohepatitis. The treatment of NAFLD with THR-β agonists seems quite promising, and other agonists are currently under development and investigation. This review aims to shine a light on the pathophysiological and epidemiological evidence regarding this relationship and the effect that treatment with THs and selective liver THR-β agonists have on hepatic lipid metabolism.
Topics: Humans; Non-alcoholic Fatty Liver Disease; Liver; Thyroid Diseases; Thyroid Hormones; Hypothyroidism; Gluconeogenesis
PubMed: 37834051
DOI: 10.3390/ijms241914605 -
Thyroid : Official Journal of the... Dec 2023Increased height has been associated with increased risk of hypothyroidism or thyroid cancer in epidemiological studies. However, the potential causal association... (Meta-Analysis)
Meta-Analysis
Increased height has been associated with increased risk of hypothyroidism or thyroid cancer in epidemiological studies. However, the potential causal association between height and hypothyroidism or thyroid cancer has not been thoroughly explored. Autoimmune thyroid disease (AITD) mainly presents as hypothyroidism, thus we aim to evaluate the causal relationship between height as exposure and its association with AITD or thyroid cancer. Mendelian randomization (MR) analyses were performed by using genetic instruments associated with height, which were selected from the largest genome-wide association meta-analysis for height in up to 5.4 million individuals. Summary-level data for AITD and thyroid cancer (including 30,234 and 3001 cases, respectively) were collected from the large number of available genome-wide association studies. Bidirectional MR was performed to test for reverse causal association between AITD and adult height. MR analyses showed that increased genetically predicted height was associated with a 4% increased risk of AITD ([CI 1.02 to 1.07], -value = 1.99E-03) per 1-standard deviation (SD) increase in genetically predicted height. The bidirectional MR did not show any causal association between AITD and adult height. Additionally, increased genetically predicted height was associated with 15% increased risk of thyroid cancer ([CI 1.07 to 1.23], -value = 2.32E-04) per 1-SD increase in height. Sensitivity analysis confirmed the main results. This MR study showed that 1-SD increase in genetically predicted height was associated with increased risk of AITD and thyroid cancer. In contrast, there was no evidence of a causal association of genetically predicted AITD with height. These results could further aid in investigation of height-related pathways as a means of gaining new mechanistic insights into AITD and thyroid cancer.
Topics: Adult; Humans; Mendelian Randomization Analysis; Genome-Wide Association Study; Hashimoto Disease; Hypothyroidism; Thyroid Neoplasms; Polymorphism, Single Nucleotide
PubMed: 37772697
DOI: 10.1089/thy.2023.0272 -
Endocrine May 2024Hypothyroidism is a relatively common endocrine disorder and is well documented to be associated with lipid abnormalities. (Review)
Review
PURPOSE
Hypothyroidism is a relatively common endocrine disorder and is well documented to be associated with lipid abnormalities.
METHODS
A narrative review was conducted of studies describing the alterations in the lipid profile accompanying both subclinical and overt hypothyroidism.
RESULTS
Lipid abnormalities are seen with TSH values in the upper end of the accepted reference range, as well as with subclinical and overt hypothyroidism. The degree of lipid derangement is generally proportional to the degree of TSH elevation. Other factors such as age, sex, and body mass index can also influence the pattern of the lipid abnormalities seen. The most robust finding with TSH elevation is increases in the low density lipoprotein cholesterol. Thyroid hormone treatment is efficacious in reversing the lipid abnormalities in both subclinical and overt hypothyroidism.
CONCLUSION
Given the association of lipid abnormalities with metabolic and cardiovascular disease, consideration of hypothyroidism as an important non-communicable disease may facilitate studies that test the hypothesis that thyroid hormone treatment to reverse hypothyroidism-associated lipid abnormalities may improve metabolic and cardiovascular outcomes.
Topics: Humans; Hypothyroidism; Lipidomics; Lipids; Lipid Metabolism
PubMed: 37329413
DOI: 10.1007/s12020-023-03420-9 -
Indian Journal of Pediatrics Oct 2023Acquired hypothyroidism is generally also referred to as juvenile hypothyroidism. Hypothyroidism is due to the deficient secretion of thyroid hormones causing metabolic... (Review)
Review
Acquired hypothyroidism is generally also referred to as juvenile hypothyroidism. Hypothyroidism is due to the deficient secretion of thyroid hormones causing metabolic and neurological sequelae at the cellular level. It can present as overt hypothyroidism wherein the thyroid hormones (T4 and T3) secretion fall and thyrotropin (TSH) rises. Acquired hypothyroidism frequently presents between 9 and 11 y of age and is rarely seen before 4 y of age. Approximately 80% of the children and adolescents are asymptomatic at the time of diagnosis. Children with moderate to severe hypothyroidism often present for evaluation of poor growth, constipation, lethargy and/or dry skin. A detailed history and examination will provide us with enough clues for diagnosing hypothyroidism. Primary hypothyroidism can be diagnosed with raised TSH with subnormal levels of T3 and T4. Titres of thyroid antibodies - Anti-thyroperoxidase (TPO) and anti-thyroglobulin (ATG) antibodies, will be high in autoimmune hypothyroidism. Subclinical hypothyroidism is diagnosed with mildly elevated or high normal levels of TSH with free T4 being in the normal range. Insufficient secretion of thyrotropin from the pituitary causes central hypothyroidism. Acquired hypothyroidism is treated by replacement with levothyroxine. Regular monitoring of thyroid profile is necessary for adjusting doses of levothyroxine. Close monitoring and individualization of levothyroxine therapy is essential for normal growth and development of the child.
Topics: Adolescent; Child; Humans; Thyroxine; Hypothyroidism; Thyroid Hormones; Thyrotropin
PubMed: 37256446
DOI: 10.1007/s12098-023-04578-w -
Frontiers in Endocrinology 2024Cardiovascular disease (CVD) remains the leading cause of death worldwide, representing a major health issue of social and economic relevance. Both hyperthyroidism and... (Review)
Review
Cardiovascular disease (CVD) remains the leading cause of death worldwide, representing a major health issue of social and economic relevance. Both hyperthyroidism and hypothyroidism are very common in the adult population, and both disorders may contribute to the onset and progression of CVD. After a brief description of the role of thyroid hormones (THs) on the physiology of the cardiovascular system and the potential mechanism that links THs alterations with changes in cardiac function, blood pressure, endothelial function, and lipid levels, we review updated data about the clinical impact of overt hypothyroidism (OH) and subclinical hypothyroidism (SCH) on CV risk, CVD, and mortality. Furthermore, we summarize the current evidence for treating SCH with levothyroxine (L-T4). Several guidelines of distinguished endocrine societies recommend treatment for SCH with TSH higher than 10 mIU/L, where the benefit of L-T4 therapy is more evident for younger people, but still controversial in those aged over 65 years. Based on current knowledge, more research efforts are needed to better address the clinical management of CV risk and CVD in the elderly affected by SCH.
Topics: Humans; Hypothyroidism; Cardiovascular Diseases; Thyroid Hormones; Thyroxine; Risk Factors
PubMed: 38887272
DOI: 10.3389/fendo.2024.1408684 -
Taiwanese Journal of Obstetrics &... Jan 2024
Topics: Humans; Pregnancy; Female; Hypothyroidism; Pregnancy Outcome; Fertilization in Vitro
PubMed: 38216270
DOI: 10.1016/j.tjog.2023.11.003