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Nutrients Nov 2023Iron deficiency (ID) is the most prevalent nutritional deficiency worldwide. Low levels of serum ferritin (SF) could affect the thyroid gland and its functioning. The... (Meta-Analysis)
Meta-Analysis Review
Iron deficiency (ID) is the most prevalent nutritional deficiency worldwide. Low levels of serum ferritin (SF) could affect the thyroid gland and its functioning. The purpose of this systematic review and meta-analysis is to summarize the main currently available evidence and analyze data on the relationship between ID and thyroid function. This study included all articles evaluating the relationship between ID and thyroid function. Quality assessment was performed using Cambridge Quality Checklists. The search strategy included the following combination of Medical Subjects Headings terms and keywords: "iron deficiency", "thyroid function", "thyroid disease", "thyroid dysfunction", and "hypothyroidism". A meta-analysis was performed to evaluate whether thyroid stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) levels differed between patients with ID and healthy controls without ID. For statistical comparison between cases and controls, the mean difference (MD) was calculated, and a subgroup analysis of pregnant and non-pregnant women was performed. Cochran's Q testing and heterogeneity indices () were used to assess statistical heterogeneity. Sensitivity analysis and publication bias analyses were also performed, both qualitatively and quantitatively. Finally, a meta-regression analysis was performed to evaluate the correlation between serum TSH or FT4 levels and SF in the study population. Ten cross-sectional studies were identified and reviewed. Patients with ID showed TSH (MD: -0.24 mIU/L; 95% CI -0.41, -0.07; = 100%, = 0.005), FT4 (MD: -1.18 pmol/L; 95% CI -1.43, -0.94; = 99%, < 0.000001), and FT3 (MD: -0.22 pmol/L; 95% CI -0.32, -0.12; = 99%, < 0.00001) levels that were significantly lower. Subgroup analysis confirmed significantly lower TSH, FT4, and FT3 levels in pregnant women. Non-pregnant women showed significantly lower serum FT4 and FT3 levels but no difference in TSH values. Meta-regression analysis showed that serum TSH and FT4 levels were positively correlated with SF levels. Our systematic review of the literature found that ID significantly increases the prevalence of thyroid autoantibody (anti-thyroglobulin antibodies and anti-thyroid peroxidase antibodies) positivity both individually and collectively. Studies currently published in the literature indicate a possible relationship between ID, thyroid function, and autoimmunity, especially in some patient groups. Data analysis shows that thyroid hormone levels are lower in patients with ID and, in particular, in pregnant women. Further studies are needed to understand the role played by iron in thyroid metabolism.
Topics: Humans; Female; Pregnancy; Thyroxine; Thyroid Function Tests; Cross-Sectional Studies; Thyroid Hormones; Thyroid Diseases; Thyrotropin; Iron Deficiencies
PubMed: 38004184
DOI: 10.3390/nu15224790 -
Antioxidants (Basel, Switzerland) Sep 2023This systematic review aims to summarise the results of controlled trials on dietary supplements (DS) usage and inflammation, oxidative stress, antioxidant status, and... (Review)
Review
Do Dietary Supplements Affect Inflammation, Oxidative Stress, and Antioxidant Status in Adults with Hypothyroidism or Hashimoto's Disease?-A Systematic Review of Controlled Trials.
This systematic review aims to summarise the results of controlled trials on dietary supplements (DS) usage and inflammation, oxidative stress, antioxidant status, and thyroid parameter improvement in hypothyroidism (HT)/Hashimoto's thyroiditis (AIT) patients. The study protocol was registered with PROSPERO (no. CRD42022365149). A comprehensive search of the PubMed, Scopus, and Web of Science databases resulted in the identification of nineteen randomised controlled trials and three non-randomised studies for the review; three studies examined the effect of supplementation with vitamin D, twelve studies-with selenium, and seven studies-with other DS. Based on very limited evidence, the lack of influence of vitamin D supplementation on inflammatory parameters was found, while no studies have examined oxidative stress and antioxidant status parameters, and only one provided results for a single thyroid parameter after an intervention. Some evidence was found proving that selenium supplementation may decrease inflammation and improve thyroid parameters, but reaching a conclusion about its influence on oxidative stress and antioxidant status is not possible because of the insufficient number of studies. Additionally, due to examining other DS (e.g., multicomponent, , and genistein) only in single studies, conclusions cannot be drawn. Further long-term, high-quality randomised controlled trials are necessary to better understand the influence of DS on inflammation, oxidative stress, and antioxidant status, as well as their potential to improve thyroid gland function in HT/AIT patients.
PubMed: 37891878
DOI: 10.3390/antiox12101798 -
Frontiers in Pharmacology 2023To evaluate the efficacy and safety of (OS) preparations for the treatment of Hashimoto's thyroiditis (HT). We searched eight databases to collect randomized...
To evaluate the efficacy and safety of (OS) preparations for the treatment of Hashimoto's thyroiditis (HT). We searched eight databases to collect randomized controlled trials (RCTs) of OS combined with a low-iodine diet or levothyroxine for HT. The search period was from inception to June 2023. Meta-analysis was performed using Revman 5.3 software after two evaluators independently screened the literature, extracted data, and evaluated the risk of bias of the included studies. The GRADE system was used to assess the certainty of evidence. A total of 14 RCTs involving 1,014 patients with HT were included. Meta-analysis showed that OS preparations combined with a low-iodine diet were more effective in reducing thyroid peroxidase antibody (TPOAb) [SMD = -3.81, 95% CI (-5.07, -2.54), < 0.00001] and thyroglobulin antibody (TgAb) [SMD = -4.73, 95% CI (-6.86, -2.61), < 0.00001] compared to a low-iodine diet. Compared with levothyroxine treatment alone, OS preparations combined with levothyroxine further reduced TPOAb [SMD = -2.04, 95% CI (-2.82, -1.26), < 0.00001], TgAb [SMD = -2.01, 95% CI (-2.68, -1.33), < 0.00001], tumor necrosis factor alpha (TNF-α) [SMD = -3.40, 95% CI (-5.66, -1.14), = 0.003], interleukin-2 (IL-2) [SMD = -2.31, 95% CI (-3.98, -0.65), = 0.006], and interleukin-6 (IL-6) [MD = -4.16, 95% CI (-6.17, -2.15), < 0.0001], and elevated free thyroxine (FT4) [SMD = 1.34, 95% CI (0.59, 2.08), = 0.0004], but no significant effect on free triiodothyronine (FT3) [SMD = 0.83, 95% CI (-0.12, 1.78), = 0.09] and thyroid stimulating hormone (TSH) [SMD = -0.80, 95% CI (-1.71, 0.11), = 0.08]. In terms of safety, three studies reported adverse reactions in 10 patients in each of the experimental and control groups. OS preparations in combination with other treatments (low-iodine diet or levothyroxine) may decrease thyroid autoantibodies and inflammatory responses in patients with HT. In HT patients with hypothyroidism, the combination of the OS preparations with levothyroxine also improved FT4. However, the quality of the included studies was generally low. Moreover, the safety of OS preparations remains unclear. Therefore, more high-quality, multicenter, large-sample RCTs are needed in the future to validate the efficacy and safety of OS preparations. https://www.crd.york.ac.uk/prospero, identifier CRD42023432663.
PubMed: 37854714
DOI: 10.3389/fphar.2023.1272124 -
Reviews in Endocrine & Metabolic... Feb 2024In recent years, a growing number of studies have examined the relationship between thyroid pathophysiology and intestinal microbiota composition. The reciprocal... (Review)
Review
In recent years, a growing number of studies have examined the relationship between thyroid pathophysiology and intestinal microbiota composition. The reciprocal influence between these two entities has been proven so extensive that some authors coined the term "gut-thyroid axis". However, since some papers reported conflicting results, several aspects of this correlation need to be clarified. This systematic review was conceived to achieve more robust information about: 1)the characteristics of gut microbiota composition in patients with the more common morphological, functional and autoimmune disorders of the thyroid; 2)the influence of gut microbial composition on micronutrients that are essential for the maintenance of thyroid homeostasis; 3)the effect of probiotics, prebiotics and synbiotics, some of the most popular over-the-counter products, on thyroid balance; 4)the opportunity to use specific dietary advice. The literature evaluation was made by three authors independently. A five steps strategy was a priori adopted. After duplicates removal, 1106 records were initially found and 38 reviews were finally included in the analysis. The systematic reviews of reviews found that: 1) some significant variations characterize the gut microbiota composition in patients with thyroid disorders. However, geographical clustering of most of the studies prevents drawing definitive conclusions on this topic; 2) the available knowledge about the effect of probiotics and synbiotics are not strong enough to suggest the routine use of these compounds in patients with thyroid disorders; 3) specific elimination nutrition should not be routine suggested to patients, which, instead have to be checked for possible micronutrients and vitamins deficiency, often owed to gastrointestinal autoimmune comorbidities.
Topics: Humans; Thyroid Gland; Prebiotics; Probiotics; Microbiota; Micronutrients
PubMed: 37824030
DOI: 10.1007/s11154-023-09839-9 -
Frontiers in Endocrinology 2023Although subclinical hypothyroidism (SCH) is related to abnormalities in left ventricular diastolic function, the use of levothyroxine as a regular treatment remains... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Although subclinical hypothyroidism (SCH) is related to abnormalities in left ventricular diastolic function, the use of levothyroxine as a regular treatment remains debatable. This meta-analysis aimed to determine whether thyroid hormone replacement therapy affects cardiac diastolic function in patients with SCH as measured by echocardiography.
METHODS
This meta-analysis included a search of the EMBASE, PubMed, Web of Science, and Cochrane Library databases from their inception to May 18, 2023, for studies analyzing cardiac morphology and functional changes in patients with SCH before and after thyroid hormone replacement. The outcome measures were cardiac morphology and diastolic and overall cardiac function, as assessed using ultrasound parameters (including ventricular wall thickness, chamber size, mitral wave flow, tissue Doppler, and speckle tracking). The quality of the studies was assessed using the Newcastle-Ottawa Scale. The standard mean differences (MDs) and 95% confidence intervals (CI) were calculated using fixed- or random-effects models.
RESULTS
Seventeen studies met the inclusion criteria. A total of 568 patients participated and completed the follow-up. All studies specifically stated that serum thyrotropin levels returned to normal by the end of the study period. Compared with baseline levels, no significant morphological changes were observed in the heart. In terms of diastolic function, we discovered that the ratios of E-velocity to A-velocity (E/A) had greatly improved after thyroid hormone replacement therapy, whereas the ratios of the mitral inflow E wave to the tissue Doppler e' wave (E/e') had not. Global longitudinal strain (GLS) increased significantly after treatment with levothyroxine.
CONCLUSION
In adult patients with SCH, thyroid hormone supplementation can partially but not completely improve parameters of diastolic function during the observation period. This meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 statement, an updated guideline for reporting systematic reviews (11) and was registered with INPLASY (INPLASY202320083).
SYSTEMATIC REVIEW REGISTRATION
https://inplasy.com/inplasy-2023-2-0083.
Topics: Adult; Humans; Echocardiography; Hormone Replacement Therapy; Hypothyroidism; Thyroxine; Ventricular Function, Left; Diastole
PubMed: 37818087
DOI: 10.3389/fendo.2023.1263861 -
Heliyon Sep 2023Several researchers performed case-control studies to explore the relationship between Hashimoto's thyroiditis(HT) and ovarian reserve using anti-Müllerian hormone(AMH)...
Evaluation of the ovarian reserve in women and adolescent girls with Hashimoto's thyroiditis by serum anti-Müllerian hormone level: A systematic review and meta-analysis.
OBJECTIVES
Several researchers performed case-control studies to explore the relationship between Hashimoto's thyroiditis(HT) and ovarian reserve using anti-Müllerian hormone(AMH) in adolescent girls and women. But the results among these studies are inconsistent and the relationship between HT and ovarian reserve is still controversial. The study aimed to conduct the meta analysis of case-control studies to confirm the relationship between HT and ovarian reserve using AMH.
METHODS
6 electronic databases including PubMed, EMBASE, the Cochrane Library, China National Knowledge Internet(CNKI), SinoMed and Wanfang were searched from inception to December 2021. Endnote X7.0 software was applied to managing all the relevant records. Then data extraction and evaluation of methodological quality of included studies were conducted after two-step selection.Review manager 5.4 version software and Stata 12.0 version software were used to perform all statistical analyses.
RESULTS
10 case-control studies involving 1202 individuals were included in the present study. The preliminary results revealed AMH values were significantly higher in adolescent girls with euthyroid HT compared with healthy adolescent girls(MD = 1.97; 95%CI, 1.43-2.51; < 0.001; = 0%). The pooled results in the subgroup of female adults with euthyroid HT showed AMH values were not significantly different between patients with HT and healthy women(MD = -0.21; 95%CI, -0.51-0.09; = 0.18; = 38%). The pooled results in the two subgroups of female adults with subclinical hypothyroidism and overt hypothyroidism both showed AMH values were significantly lower in the HT group compared with healthy women [(MD = -0.60; 95%CI, -0.86 to -0.34; < 0.001; = 0%), (MD = -1.34; 95%CI, -1.94 to -0.74; < 0.001; = 65%)].
CONCLUSIONS
Ovarian reserve evaluated by serum AMH concentration is affected by female adults with subclinical hypothyroidism and overt hypothyroidism. The AMH level was significantly higher in euthyroid adolescent girls.
PubMed: 37809909
DOI: 10.1016/j.heliyon.2023.e19204 -
Cureus Sep 2023Diabetes mellitus (DM) and thyroid dysfunction are two disorders that are closely related. This systematic review aimed to investigate the effect of levothyroxine... (Review)
Review
Diabetes mellitus (DM) and thyroid dysfunction are two disorders that are closely related. This systematic review aimed to investigate the effect of levothyroxine supplementation on diabetic nephropathy in type 2 diabetic patients with co-existing thyroid dysfunction. We explored medical databases such as PubMed, Medline, Multidisciplinary Digital Publishing Institute (MDPI), and Cochrane Library for relevant medical literature. The papers were screened, and 12 research papers involving 10,371 patients were identified after applying eligibility criteria and quality assessment using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The included papers analyzed the effect of aberrant thyroid profile on kidney disease in diabetic individuals and the role that achieving euthyroid status with levothyroxine supplementation could play in diabetic nephropathy. Reduced free triiodothyronine (FT3) was the most common independent factor associated with diabetic microvascular and macrovascular complications. Levothyroxine (LT4) regimen was more effective than the placebo in lowering urinary albumin excretion rate (UAER), low-density lipoprotein cholesterol, and uric acid and decreasing oxidative stress overall. However, replacement therapy's effect may differ in the short and long terms. Thyroid hormone replacement therapy (THRT) may reduce the risk of diabetic nephropathy and cardiovascular disease (CVD) development in hypothyroid patients, but more randomized trials are needed to confirm the effect of THRT.
PubMed: 37809188
DOI: 10.7759/cureus.44729 -
BMC Public Health Sep 2023Knowledge surrounding the association between exposure to pesticides and hypothyroidism is inconsistent and controversial. (Meta-Analysis)
Meta-Analysis
BACKGROUND
Knowledge surrounding the association between exposure to pesticides and hypothyroidism is inconsistent and controversial.
METHODS
The aim of present study was, therefore, to review scientific evidence systematically and conduct a meta-analysis into the contribution of exposure to pesticides to hypothyroidism. PubMed, Scopus, Web of Science, and Google Scholar were searched. The findings are presented as OR, HR, PR, IRR, and 95% confidence interval (95%CI). A fixed-effect model using the inverse-variance method and random-effects inverse-variance model with DerSimonian-Laird method were used for estimating the pooled estimates. Cochran Q and I tests were used to confirm the heterogeneity of selected studies.
RESULTS
Twelve studies were included in the systematic review, and 9 studies in the meta-analysis. Epidemiological evidence suggested that exposure to insecticides including organochlorines, organophosphates, and pyrethroids increased risk of hypothyroidism (adjusted odds ratio (aOR) = 1.23, 95%CI = 1.14, 1.33 for organochlorines, aOR = 1.12, 95%CI = 1.07, 1.17 for organophosphates, aOR = 1.15, 95%CI = 1.03, 1.28 for pyrethroids). Exposure to herbicides also increased risk of hypothyroidism (aOR = 1.06, 95%CI = 1.02, 1.10). However, exposure to fungicides and fumigants was not found to be associated with hypothyroidism.
CONCLUSION
To increase current knowledge and confirm evidence to date future research needs to center on large-scale longitudinal epidemiological and biological studies, examination of dose-response relationships, the controlling of relevant confounding variables, using standardized and high sensitivity tools, and investigating the effects of environmental exposure.
Topics: Humans; Pesticides; Insecticides; Environmental Exposure; Hypothyroidism; Pyrethrins
PubMed: 37752464
DOI: 10.1186/s12889-023-16721-5 -
Irish Journal of Medical Science Apr 2024The major changes in the timing of meals during Ramadan may be challenging for hypothyroid patients on levothyroxine. We aimed to study the effect of Ramadan fasting on... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
The major changes in the timing of meals during Ramadan may be challenging for hypothyroid patients on levothyroxine. We aimed to study the effect of Ramadan fasting on thyroid functions in hypothyroid patients taking levothyroxine.
METHODS
We did a comprehensive search of 8 databases for Randomized controlled studies (RCTs) and observational studies investigating the effect of Ramadan fasting on thyroid functions in hypothyroid individuals taking levothyroxine. Relevant data was extracted and analyzed. Mean difference (MD) and standard deviation (SD) were used to evaluate the continuous data. Risk ratios (RR) with a 95% confidence interval were used for outcomes constituting dichotomous data. National Institutes of Health (NIH) tools were used to assess the risk of bias.
RESULTS
Fourteen studies met our inclusion criteria, 3 RCTs, and 11 observational studies, all designed as pre-post studies. Ramadan fasting was associated with a statistically significant increase in TSH in patients who were euthyroid before Ramadan (MD = -0.76 [95% CI; -1.27, -0.25]). However, free thyroxine (FT4) was found to be stable (MD = 0.01, [95% CI; -0.03, 0.06]). All timing points were associated with a significant increase in TSH levels after Ramadan, pre-iftar (MD = -0.69 [95% CI; -1.03, -0.36]), post-iftar (MD = -0.76 [95% CI; -1.12, -0.39]), and pre-suhoor (MD = -1.19 [95% CI; -2.18, -0.19]).
CONCLUSION
TSH increases significantly after Ramadan. No timing point has superiority in maintaining thyroid control. However, choosing the timing should be individualized according to the patient's preference to guarantee the most possible compliance.
Topics: Humans; Thyroxine; Hypothyroidism; Fasting; Thyrotropin
PubMed: 37733226
DOI: 10.1007/s11845-023-03526-z -
Endocrine May 2024To assess the prospective association between metabolic syndrome (MetS), its components, and incidence of thyroid disorders by conducting a systematic review and... (Meta-Analysis)
Meta-Analysis
PURPOSE
To assess the prospective association between metabolic syndrome (MetS), its components, and incidence of thyroid disorders by conducting a systematic review and meta-analysis.
METHODS
A systematic search was performed in Ovid Medline, Embase.com, and Cochrane CENTRAL from inception to February 22, 2023. Publications from prospective studies were included if they provided data on baseline MetS status or one of its components and assessed the incidence of thyroid disorders over time. A random effects meta-analysis was conducted to calculate the odds ratio (OR) for developing thyroid disorders.
RESULTS
After full-text screening of 2927 articles, seven studies met our inclusion criteria. Two of these studies assessed MetS as an exposure (N = 71,727) and were included in our meta-analysis. The association between MetS at baseline and incidence of overt hypothyroidism at follow-up yielded an OR of 0.78 (95% confidence interval [CI]: 0.52-1.16 for two studies, I = 0%). Pooled analysis was not possible for subclinical hypothyroidism, due to large heterogeneity (I = 92.3%), nor for hyperthyroidism, as only one study assessed this association. We found evidence of an increased risk of overt (RR: 3.10 (1.56-4.64, I = 0%) and subclinical hypothyroidism (RR 1.50 (1.05-1.94), I = 0%) in individuals with obesity at baseline. There was a lower odds of developing overt hyperthyroidism in individuals with prediabetes at baseline (OR: 0.68 (0.47-0.98), I = 0%).
CONCLUSIONS
We were unable to draw firm conclusions regarding the association between MetS and the incidence of thyroid disorders due to the limited number of available studies and the presence of important heterogeneity in reporting results. However, we did find an association between obesity at baseline and incidence of overt and subclinical hypothyroidism.
Topics: Humans; Metabolic Syndrome; Incidence; Thyroid Diseases; Hypothyroidism
PubMed: 37688711
DOI: 10.1007/s12020-023-03503-7