Effects of TSH on the function of human umbilical vein endothelial cells

Analysis of correlative factors of female coronary slow-flow phenomenon: A retrospective study

The coronary slow-flow phenomenon (CSFP) is a manifestation of coronary artery disease wherein coronary angiography reveals no apparent stenosis; however, there is a delay in blood flow perfusion. Given its increased occurrence in male patients, with the majority of subjects in previous studies being male, this study aimed to explore whether distinct risk factors are present in female patients with CSFP. This single-center retrospective study focused on female patients diagnosed with CSFP by using coronary angiography. Eligible patients meeting the predefined inclusion and exclusion criteria were divided into the study group (presenting with CSFP) and control group (displaying normal epicardial coronary arteries). Comparative analyses of clinical and diagnostic data were performed. Ninety-two patients with CSFP and an equal number of controls were enrolled in this study. Patients with CSFP exhibited a higher prevalence of smokers (P = .017) and a heightened incidence of diabetes mellitus (DM) (P = .007). Significantly elevated levels of total cholesterol (TC) (P = .034) and free fatty acids (FFA) (P = .016) were observed in the CSFP group compared to those in the control group. Additionally, patients with CSFP displayed lower levels of apolipoprotein E (ApoE) (P = .092), free thyroxine (FT4) (P = .001), and total thyroxine (TT4) (P = .025). Logistic regression analysis indicated that smoking (P = .019), FFA (P < .001), ApoE (P = .015), and FT4 (P < .001) were independent risk factors for CSFP, accounting for confounding factors. Additionally, the area under the ROC curve (AUC) of the combined effect of smoking, ApoE, FT4, and FFA on CSFP was 0.793 (95% CI: 0.729-0.857, P < .01). In addition to the established risk factors for smoking, diabetes, and hyperlipidemia, female patients with CSFP exhibited significant differences in apoE, FFA, FT4, and TT4 levels compared to the control group. Smoking, FFA, and FT4 levels emerged as independent risk factors for CSFP.

Subclinical Hypothyroidism Predicted Adverse Cardiovascular Events in Patients with Ejection Fraction Preserved Heart Failure

Background

Subclinical hypothyroidism (SH) increases the risk of cardiovascular events, however the influence of SH on prognosis of ejection fraction preserved heart failure (HFpEF) is not fully understood.

Methods

In this prospective observational study, patients with HFpEF were divided into euthyroidism group (n = 413) and SH group (n = 79). Patients were followed up for at least 30 months to examine the association between SH and cardiovascular events in patients with HFpEF. The primary end point was composite cardiovascular events (cardiovascular death and re-hospitalization). The patients underwent flow-mediated dilation (FMD) measurement by ultrasound in order to value endothelial function.

Results

The rate of composite cardiovascular events was higher in SH group than in euthyroidism group (54.49% and 26.36%, respectively; p < 0.001). The higher risk of cardiovascular events in SH group was primarily due to a higher risk of re-hospitalization compared to euthyroidism group (45.56% and 20.58%, respectively; p < 0.001). The rate of cardiovascular death was higher in SH group than in euthyroidism group (13.92% and 5.81%, respectively; p = 0.017). Cox proportional hazards regression showed that SH (hazard ratios [HR] 1.921, 95% confidence interval [CI] 1.139-3.240), level of TSH (HR 1.025, 95% CI 1.010-1.054), age (HR 1.017, 95% CI 1.002-1.034), LVEF (HR 0.975, 95% CI 0.953-0.996), atrial fibrillation (HR 1.581, 95% CI 1.083-2.307), eGFR (HR 0.987, 95% CI 0.978-0.997), and NYHA cardiac function (HR 2.342, 95% CI 1.649-3.326) were independent predictors of cardiovascular events in patients with HFpEF (all P < 0.05).

Conclusion

Subclinical hypothyroidism was associated with increased cardiovascular events and death in patients with HFpEF.

Subclinical Hypothyroidism, Kidney, and Heart from Normal to Uremic Milieu

Thyroid hormone (TH) imbalances, particularly subclinical hypothyroidism (SCHT), are associated with chronic kidney disease (CKD) and end-stage kidney disease (ESKD). SCHT is more prevalent in CKD and ESKD patients than in the general population, and this condition increases the risk of cardiovascular disease (CVD) morbidity and mortality. The risk of CVD is higher in CKD and ESKD patients compared with the general population. Traditional and nontraditional risk factors, including TH abnormalities, contribute to the high CVD burden in CKD and ESKD patients. The review discusses the link between CKD and hypothyroidism, with a focus on SCHT, and the mechanisms that lead to CVD burden.

A high TSH level is associated with diabetic macular edema: a cross-sectional study of patients with type 2 diabetes mellitus

AIMS

In this study, we determined the association between thyroid-stimulating hormone (TSH) and diabetic macular edema (DME) by assessing the prevalence and risk factors for DME in type 2 diabetes mellitus (T2DM) patients with different thyroid dysfunctions.

METHODS

This was a retrospective cross-sectional study including 1003 euthyroid and 92 subclinical hypothyroidism (SCH) T2DM patients. DME status was detected by optical coherence tomography (OCT). The association between TSH and DME and the impact of TSH on DME were analyzed.

RESULTS

The DME prevalence was 28.3% in the SCH patients and 14.0% in the euthyroid population. The serum FT4 (P = 0.001) and FT3 (P < 0.001) levels were significantly higher in the non-DME group than in the DME group, and the TSH level (P < 0.001) was significantly lower. Four subgroups (G1-G4) were divided by TSH level, and the chi-square test indicated that even in the normal range, the TSH level was positively related to DME prevalence (P = 0.001). Subgroup data indicated that the association between TSH and DME detected by OCT (P = 0.001) was stronger than the correlation between TSH and diabetic retinopathy detected by digital retinal photographs (P = 0.027). The logistic regression model confirmed that elevated TSH was an independent risk factor for DME. The odds ratio was 1.53 (P = 0.02).

CONCLUSIONS

A high TSH level was an independent risk factor for DME. More attention should be given to the TSH level in T2DM patients due to its relationship with diabetic complications.

Iodine deficiency in pregnancy along a concentration gradient is associated with increased severity of preeclampsia in rural Eastern Cape, South Africa

Background

Preeclampsia is a leading cause of maternal mortality and morbidity in South Africa. Iodine deficiency in pregnancy, which is amenable to correction through iodine supplementation, has been reported to increase the risk of preeclampsia. However, the association of iodine nutrition status with preeclampsia in South Africa has not been studied.

Methods

We enrolled 51 randomly selected normotensive pregnant controls at term together with 51 consecutively selected cases of preeclampsia and 51 cases of severe preeclampsia/eclampsia, all in the third trimester, from Mthatha Regional and Nelson Mandela Academic Hospital in the Eastern Cape Province. Urinary iodine concentration (UIC), serum thyroid-stimulating hormone (TSH), triiodothyronine (FT3), thyroxine (FT4) and thyroglobulin (Tg) levels were compared between cases and controls.

Results

The respective chronological and gestational ages at enrolment for normotensive, preeclampsia and severe preeclampsia/eclampsia participants were: age 23, 24 and 19 years (p = 0.001), and gestational age 38, 34, and 35 weeks (p < 0.001). The median gravidity was 1 for all three groups. The median UIC, FT4, FT3 revealed a decreasing and Tg a rising trend with the severity of preeclampsia (p < 0.05). TSH had a non-significant rising trend (p > 0.05). The respective median values for normotensive, preeclampsia and severe preeclampsia/eclampsia participants were UIC 217.1, 127.7, and 98.8 μg/L; FT4 14.2, 13.7, and 12. pmol/L; FT3 4.8, 4.4, and 4.0 pmol//L; Tg 19.4, 21.4, and 32. Nine microgram per liter; TSH 2.3, 2.3, and 2.5 mIU/L. UIC < 100 μg/L, Tg > 16 μg/L and FT4 < 11.3 pmol/L were independent predictors of preeclampsia/eclampsia syndrome.

Conclusion

Women with severe preeclampsia/eclampsia had significantly low UIC and high Tg, suggesting protracted inadequate iodine intake. Inadequate iodine intake during pregnancy severe enough to cause elevated Tg and FT4 deficiency was associated with an increased risk of severe preeclampsia/eclampsia.

Essentiality, relevance, and efficacy of adjuvant/combinational therapy in the management of thyroid dysfunctions

Thyroid dysfunction is the most prevalent endocrine disorder worldwide having an epidemiology of 11% in Indians, 4.6% in the United Kingdom, and 2% in the United States of America among the overall population. The common thyroid disorders include hypothyroidism, hyperthyroidism, Hashimoto's thyroiditis, and thyroid cancer. This review briefly elaborates the molecular regulation and mechanism of thyroid hormone, and its associated thyroid disorders. The thyroid hormones regulate critical biochemical functions in brain development and function. Hypothyroidism is mainly associated with dysregulation of cytokines, increased ROS production, and altered signal transduction in major regions of the brain. In addition, it is associated with reduced antioxidant capacity and increased oxidative stress in humans. Though 70% of thyroid disorders are caused by heredity, environmental factors have a significant influence in developing autoimmune thyroid disorders in people who are predisposed to them. This drives us to understand the relationship between environmental factors and thyroid dysregulated disorders. The treatment option for the thyroid disorder includes antithyroid medications, receiving radioactive iodine therapy, or surgery at a critical stage. However, antithyroid drugs are not typically used long-term in thyroid disease due to the high recurrence rate. Adjuvant treatment of antioxidants can produce better outcomes with anti-thyroid drug treatment. Thus, Adjuvant therapy has been proven as an effective strategy for managing thyroid dysfunction, herbal remedies can be used to treat thyroid dysfunction in the future, which in turn can reduce the prevalence of thyroid disorders.

Internal Jugular Vein Thrombosis After Microwave Ablation of Cervical Lymph Node Metastasis in Papillary Thyroid Microcarcinoma: A Case Report

In this study, two patients with papillary thyroid carcinoma and lymph node metastasis were treated by Dr. Shurong Wang's team and are reported. The two patients refused surgery and underwent microwave ablation (MWA) of the thyroid and lymph node lesions. Ultrasound review 2 days after MWA revealed internal jugular vein thrombosis. Patient #1 received low molecular weight heparin calcium injection, Xueshuantong injection, Xiangdan injection, and rivaroxaban. Patient #2 was treated with enoxaparin sodium injection, Xueshuantong injection, urokinase, and warfarin sodium tablet. The thrombus was successfully managed in each patient using anticoagulant treatment. Such complication of MWA has not been reported in many cases before. According to the relevant literature, thrombosis after thyroid cancer ablation might be related to subclinical hypothyroidism, increased heme oxidase 1 (HO-1) levels in the blood of patients with papillary thyroid cancer, and increased platelet content and mean platelet volume in patients with thyroid cancer. No specific cause of thrombosis was identified in the two cases reported here. No recurrence was observed after 1 (patient #1) and 4 (#2) years of follow-up. In conclusion, patients with papillary thyroid carcinoma and lymph node metastasis should undergo color Doppler ultrasound of the neck after MWA of thyroid lesions and neck metastasis.

Mildly elevated thyroid-stimulating hormone is associated with endothelial dysfunction and severe preeclampsia among pregnant women with insufficient iodine intake in Eastern Cape province, South Africa

BACKGROUND

Preeclampsia and hypothyroidism are associated with endothelial dysfunction. Iodine deficiency is a risk factor for subclinical hypothyroidism in pregnancy. However, there is a paucity of data on the relationship between iodine nutrition state in pregnancy, the degree of endothelial dysfunction, and the risk of preeclampsia.

METHODS

Ninety-five normotensive pregnant women, 50 women with preeclampsia with no severe features, and 50 women with severe preeclampsia were enrolled into the current study from the maternity units of Nelson Mandela Academic Hospital and Mthatha Regional Hospitals in Eastern Cape Province, South Africa. Urinary iodine concentration (UIC), serum markers of thyroid function, aortic augmentation index, and pulse wave velocity (PWV) were compared.

RESULTS

Median UIC was 167.5, 127.7, and 88.5 µg/L, respectively for normotensive pregnant women, those with preeclampsia and severe preeclampsia (p = .150). Participants with severe preeclampsia had significantly higher median thyroid-stimulating hormone (TSH) and oxidized LDL than normotensive and preeclamptic women without severe features (respectively 3.0, 2.3, and 2.3 IU/L; 1.2, 1.0, and 1.0 IU/L, p < .05). The median Aortic augmentation index was 7.5, 19.0, and 21.0 (p < .001), and the pulse wave velocity 5.1, 5.7, and 6.3, respectively for normotensive, preeclampsia, and severe preeclampsia participants (both p < .001). In linear regressions, TSH, age, and hypertensive disease were independent predictors of elevated PWV.

CONCLUSION

Upper normal-range TSH levels in women with severe preeclampsia were associated with markers of endothelial dysfunction. The low UIC and trend towards the elevation of thyroglobulin suggest that inadequate iodine intake may have increased TSH levels and indirectly caused endothelial dysfunction.

Oxidative stress and radioiodine treatment of differentiated thyroid cancer

It is hypothesized that the oxidative stress level in thyroid cancer patients is additionally upregulated by radioactive iodine (RAI) treatment, that may exert an important impact on future health concerns. In our study, we evaluated the oxidative stress level changes using the measurement of malondialdehyde (MDA) concentration in patients with differentiated thyroid cancer (DTC) undergoing RAI treatment. Considering the results obtained in the study group, the serum levels of MDA in DTC patients were significantly higher compared to the healthy subjects (p < 0.05). The MDA concentration was significantly higher on the third day after RAI (p < 0.001) and significantly lower one year after RAI (p < 0.05) in DTC patients compared to the baseline concentration. Moreover, the redox stabilization after RAI treatment in patients with DTC during a year-long observation was demonstrated. Accordingly, an increased oxidative stress impact on the related biochemical parameters reflecting the health conditions of the DTC patients was determined. Our study showed that increased oxidative stress reflected by MDA measurements in DTC patients is further enhanced by RAI, but this effect is no longer observed one year after the therapy.

Recognized and Potentially New Biomarkers-Their Role in Diagnosis and Prognosis of Cardiovascular Disease

Atherosclerosis and its consequences are the leading cause of mortality in the world. For this reason, we have reviewed atherosclerosis biomarkers and selected the most promising ones for review. We focused mainly on biomarkers related to inflammation and oxidative stress, such as the highly sensitive C-reactive protein (hs-CRP), interleukin 6 (IL-6), and lipoprotein-associated phospholipase A2 (Lp-PLA2). The microRNA (miRNA) and the usefulness of the bone mineralization, glucose, and lipid metabolism marker osteocalcin (OC) were also reviewed. The last biomarker we considered was angiogenin (ANG). Our review shows that due to the multifactorial nature of atherosclerosis, no single marker is known so far, the determination of which would unambiguously assess the severity of atherosclerosis and help without any doubt in the prognosis of cardiovascular risk.

Is There an Association Between Hypothyroidism and Sexual Dysfunction: A Systematic Review and Cumulative Analysis

INTRODUCTION

Many investigators have found a detrimental effect on sexual functioning developed by hypothyroidism in both sexes, but a cumulative analysis has not been conducted.

AIM

This study aims to summarize and quantify the association between overt or subclinical hypothyroidism and the risk of sexual dysfunction (SD) through a meta-analysis.

METHODS

4 electronic databases were systematically searched. The quality of evidence was rated by the GRADE approach. This meta-analysis was registered on the PROSPERO (ID: CRD42020186967).

MAIN OUTCOME MEASURE

The strength of the relationship between overt/subclinical hypothyroidism and SD was quantified by presenting the relative risk (RR) with its 95% confidence interval (CI).

RESULTS

7 studies involving 460 patients with hypothyroidism and 2,143 healthy controls were included in this meta-analysis. Among the 7 included studies, 2 studies were provided the data of both overt and subclinical hypothyroidism. Pooled results from 4 included studies investigating overt hypothyroidism indicated that overt hypothyroidism led to significant SD in both sexes (RR = 2.26, 95% CI: 1.42 to 3.62, P = 0.001), while synthetic RR of 5 eligible studies reporting subclinical hypothyroidism failed to find a positive association between subclinical hypothyroidism and SD (RR = 1.3, 95% CI: 0.85 to 1.99, P = 0.229), irrespective of gender (all P > 0.05). Subgroup analyses revealed that women with overt hypothyroidism rather than men with overt hypothyroidism were correlated with a significant higher risk of SD. The quality of evidence in the study of overt hypothyroidism and subclinical hypothyroidism was considered low and moderate, respectively.

CONCLUSION

SD is a devastating problem in female patients with clinical hypothyroidism but insusceptible in either women or men with subclinical hypothyroidism. Clinicians should be aware of these phenomena and manage the sufferers accordingly in clinical practice. More rigorous studies are still needed to validate this evidence. Shen M, Li X, Wu W, et al. Is There an Association Between Hypothyroidism and Sexual Dysfunction: A Systematic Review and Cumulative Analysis. Sex Med 2021;9:100345.

FMD and CIMT: Surrogate Markers of Atherosclerosis in Subclinical and Overt Hypothyroidism in Sub Himalyan Region

INTRODUCTION

Hypothyroidism increases the risk of atherosclerosis. Carotid intima-media thickness (CIMT) and flow-mediated dilation (FMD) have been used as a noninvasive method to detect atherosclerosis. But the literature is scarce on patients with subclinical hypothyroidism. Such a study was not done in our region, so we conducted this study at a tertiary care center to compare CIMT and FMD among subclinical and overt hypothyroid patients and to analyze the risk of atherosclerosis.

METHODS

We evaluated 68 patients aged 18-50 years, with newly diagnosed hypothyroidism. We divided them into overt and subclinical hypothyroidism groups and compared the findings. All analyses were performed by the computerized SPSS 17.0. The results were noted as means ± SD and percentage. Student's t-test was used to compare continuous variables, and the Chi-square test was used to compare differences.

RESULTS

The total number of patients with dyslipidemia in the subclinical hypothyroidism (SCH) group was 22 (45.83%) and in the overt hypothyroidism (OH) group was 26 (54.16%) with a P- value of 0.009. The mean FMD% in subclinical hypothyroidism patients was 6.9816 ± 3.4224 and in overt hypothyroidism patients was 5.3670 ± 2.7278 (P = 0.03). The mean CIMT was 0.5009 ± 0.0732, CIMT in the SCH group was 0.5082 ± 0.0672 and in the OH group was 0.5305 ± 0.0799 (P = 0.2).

CONCLUSION

The outcome of this study specifies that hypothyroidism is associated with endothelial dysfunction as established by impaired FMD, and it may be the first marker of atherosclerosis appearing before any structural evidence like CIMT. We can speculate that there is a link between subclinical hypothyroidism and atherosclerosis, and thyroxine replacement in SCH may help to prevent the progression of atherosclerosis.

Long non-coding RNA NEAT1 regulates endothelial functions in subclinical hypothyroidism through miR-126/TRAF7 pathway

Subclinical hypothyroidism (SCH) is associated with increased risks of endothelial dysfunction and atherosclerosis, but the mechanisms remain unclear. In our previous study, microRNA-126-3p was downregulated in SCH, but the role and regulatory mechanism of miR-126 in SCH has not been investigated. A SCH mouse model was established by feeding mice methimazole. Both primary endothelial cells (ECs) and HUVECs were cultured. The expression levels of key molecules were detected via quantitative RT-PCR, western blotting, and immunofluorescence. Wire myography was used to analyze the changes in vascular tones. A dual-luciferase assay was used to investigate the relationship between lncRNAs, microRNAs and target genes. In detail, it was shown that the expression levels of miR-126-3p were significantly decreased in both the SCH vasculature and HUVECs. MiR-126 supplementation suppressed HUVEC apoptosis and improved vascular function. Moreover, miR-126 could bind to the 3'-untranslated region of TRAF7, thus, regulating the C-FLIP pathway and endothelial apoptosis. Furthermore, lncRNA NEAT1 was upregulated upon TSH treatment and could function as a ceRNA and bind to miR-126, thus, modulating its expression level and vascular function. Finally, the NEAT1/miR-126/TRAF7 axis functions in response to TSH and regulates endothelial functions in SCH in vitro and in vivo. In conclusion, dysregulation of the NEAT1/miR-126/TRAF7 axis is responsible for impaired endothelial functions in SCH. Targeting this axis might become a promising treatment strategy or improving endothelial functions in SCH.

Insufficient iodine nutrition status and the risk of pre-eclampsia: a systemic review and meta-analysis

BACKGROUND

Although subclinical hypothyroidism in pregnancy is one of the established risk factors for pre-eclampsia, the link between iodine deficiency, the main cause of hypothyroidism, and pre-eclampsia remains uncertain. We conducted a systematic review to determine the iodine nutrition status of pregnant women with and without pre-eclampsia and the risk of pre-eclampsia due to iodine deficiency.

METHODS

MEDLINE, EMBASE, Google Scholar, Scopus and Africa-Wide Information were searched up to 30th June 2020. Random-effect model meta-analysis was used to pool mean difference in urinary iodine concentration (UIC) between pre-eclamptic and normotensive controls and pool ORs and incidence rates of pre-eclampsia among women with UIC <150 µg/L.

RESULTS

Five eligible studies were included in the meta-analysis. There was a significant difference in the pooled mean UIC of 254 pre-eclamptic women and 210 normotensive controls enrolled in three eligible case-control studies (mean UIC 164.4 µg/L (95% CI 45.1 to 283.6, p<0.01, I² >50)). The overall proportions of pre-eclampsia among women with UIC <150 µg/L and UIC >150 µg/L in two cross-sectional studies were 203/214 and 67/247, respectively, with a pooled OR of 0.01 (95% CI 0 to 4.23, p=0.14, I² >50) for pre-eclampsia among women with UIC >150 µg/L. The overall incidence of pre-eclampsia among women with UIC <150 µg/L and UIC >150 µg/L in two cohort studies was 6/1411 and 3/2478, respectively, with a pooled risk ratio of 2.85 (95% CI 0.42 to 20.05, p=0.09, I² <25).

CONCLUSION

Although pre-eclamptic women seem to have lower UIC than normotensive pregnant women, the available data are insufficient to provide a conclusive answer on association of iodine deficiency with pre-eclampsia risk.

PROSPERO REGISTRATION NUMBER

CRD42018099427.

Regulation of nitric oxide production in hypothyroidism

Hypothyroidism is a common endocrine disorder that predominantly occurs in females. It is associated with an increased risk of cardiovascular diseases (CVD), but the molecular mechanism is not known. Disturbance in lipid metabolism, the regulation of oxidative stress, and inflammation characterize the progression of subclinical hypothyroidism. The initiation and progression of endothelial dysfunction also exhibit these changes, which is the initial step in developing CVD. Animal and human studies highlight the critical role of nitric oxide (NO) as a reliable biomarker for cardiovascular risk in subclinical and clinical hypothyroidism. In this review, we summarize the recent literature findings associated with NO production by the thyroid hormones in both physiological and pathophysiological conditions. We also discuss the levothyroxine treatment effect on serum NO levels in hypothyroid patients.

TSH inhibits eNOS expression in HMEC-1 cells through the TSHR/PI3K/AKT signaling pathway

OBJECTIVE

To investigate the effects of thyroid-stimulating hormone (TSH) on the expression of endothelial nitric oxide synthase (eNOS) in human microvascular endothelial cells (HMEC-1) and explore the potential mechanism.

MATERIALS AND METHODS

Expression of thyroid-stimulating hormone receptor (TSHR) in HMEC-1 cells was determined by immunofluorescence, reverse transcription-polymerase chain reaction (RT-PCR), and Western blotting. Cell proliferation and the production of nitric oxide (NO) and superoxide anion (SA) were measured after TSH treatment. eNOS expression and AKT phosphorylation were detected by Western blotting.

RESULTS

TSHR was expressed in HMEC-1 cells. TSH promoted HMEC-1 cell proliferation and SA production, but inhibited NO generation by dose-dependent blocking of mRNA and protein expression of eNOS. Mechanism studies demonstrated that TSH promoted AKT phosphorylation (P<0.05), and that LY294002 inhibited the reduction of eNOS expression by TSH. Moreover, TSH activated the AKT signaling pathway through binding to TSHR on HMEC-1 cells.

CONCLUSIONS

TSH inhibits NO production via the TSHR/AKT signaling pathway.

Raised TSH is associated with endothelial dysfunction in Metabolic Syndrome: A case control study

INTRODUCTION

Endothelial dysfunction has been considered as one of the important factors in pathogenesis of Metabolic Syndrome (Met S). Subclinical hypothyroidism (SCH) has also been reported to be associated with Met S. The aim of our study is to evaluate the association of raised TSH with mediators of endothelial dysfunction in Met S with Subclinical hypothyroidism as compared to healthy controls.

METHODS

Study population consisted of 100 subjects, out of which 50 were cases of Met S and 50 were healthy controls. Met S group were further divided into two, based on the presence & absence of SCH. Serum insulin, T3, T4, TSH were measured by chemiluminescence based immunoassay (CLIA). Serum nitric oxide (NO) levels were measured by Modified Griess's method and serum endothelin-1 (ET-1) levels were measured by ELISA.

RESULTS

Out of 50 cases of Met S, SCH was diagnosed in 22. The mean serum TSH levels were significantly higher in Met S cases as compared to healthy controls (5.7 ± 1.2 μIU/mL vs. 2.3 ± 1.6 μIU/mL, P <0.0001). Mean serum NO levels were significantly lower in Met S cases as compared to healthy control (15.4 ± 10 μM vs. 21 ± 10 μM, p = 0.009). Mean serum ET-1 levels were significantly higher in Met S cases as compared to healthy controls (2.68 ± 1.7 fmol/mL vs. 2.1 ± 0.84 fmol/mL, p = 0.011). On Pearson's correlation analysis, TSH showed positive correlation with ET-1 (r = 0.341, p = 0.001) and negative correlation with NO (r = -0.331, p = 0.001). Binary logistic regression analysis showed that TSH, NO and ET-1 has significant odd's ratio for predicting Met S.

CONCLUSION

Met S cases were screened for thyroid abnormalities and found to have 44% of SCH along with co-existing endothelial dysfunction. Raised TSH in SCH could cause endothelial dysfunction which may lead to Met S and associated co-morbidities. Present study gives new insight in linking endothelial dysfunction and raised TSH in Met S. Therefore, Met S cases should be screened for SCH and treated appropriately to attenuate endothelial dysfunction and associated comorbidities in Met S.

Hypertension in Thyroid Disorders

Arterial hypertension represents a major global health concern; more than one fourth of the population is affected by high blood pressure. Albeit the underlying cause of the disease remains unclear in the vast majority of the cases, ~10% are of secondary origin. Endocrine disorders are common illnesses and some of them may lead to elevated blood pressure, among which thyroid diseases are of high prevalence and often overlooked, especially in mild cases. Overt and subclinical hyper- and hypothyroidism can both lead to (mostly mild) hypertension; however, the underlying mechanisms are only partially understood. The results of clinical studies are often controversial. During the past decades, some genetic mutations in the hypothalamus-pituitary-thyroid axis with cardiovascular consequences were revealed. Atherosclerotic changes resulting from lipid abnormalities due to thyroid dysfunction also affect the vasculature and can cause elevated blood pressure. The review gives a synopsis of our knowledge how thyroid hormone metabolism and functional thyroid diseases affect the cardiovascular system, their negative impact and causative role in the development of hypertension.

Subclinical Hypothyroidism and Coronary Revascularization After Coronary Artery Bypass Grafting

We aimed to investigate long-term cardiovascular sequelae after coronary artery bypass grafting (CABG) in patients with subclinical hypothyroidism (SCH). All-cause and cardiovascular-related mortality, and cardiovascular events were retrospectively reviewed in 222 euthyroid and 36 SCH patients who underwent CABG. During a mean follow-up period of 8.2 ± 4.1 years, there were 90 incidents of all-cause deaths, 20 cardiovascular-related deaths, 70 major cardiovascular adverse events, 6 myocardial infarctions, 12 unstable anginas, 31 strokes, 23 hospitalizations due to heart failure, 15 atrial fibrillation (AF) events, and 27 coronary revascularizations. The incidence rate of coronary revascularization was significantly higher in patients with SCH (n = 6, 16.6%) than in euthyroid patients (n = 20, 9.0%), with a hazard ratio (HR) of 3.179 (95% confidence interval [CI] 1.174, 8.605; p = 0.023) after adjustment. In subgroup analysis, SCH patients who experienced postoperative AF within 3 months after CABG surgery had a significantly higher risk of coronary revascularization (n = 4, 25.0%) than euthyroid patients without AF (n = 14, 8.9%) after adjustment (HR 11.759, 95% CI 2.747, 50.343, p = 0.001). The frequency of fatal or nonfatal unstable angina was also higher in patients with SCH (n = 2, 12.5%) than in euthyroid patients (n = 4, 2.5%) (HR 16.999, 95% CI 2.242, 128.860, p = 0.006). In conclusion, preoperative SCH is associated with less favorable cardiovascular outcomes, especially coronary revascularization after CABG. Moreover, SCH patients who develop postoperative AF exhibit significantly increased risks of unstable angina and coronary revascularization. Preoperative evaluation of thyroid function may be helpful for predicting long-term outcomes after CABG.

Effects of thyroid-stimulating hormone on adhesion molecules and pro-inflammatory cytokines secretion in human umbilical vein endothelial cells

Atherosclerosis is a multifactorial disorder, which affects the arterial wall. It has been reported that, hypothyroidism and thyroid hormone deficiency are related to cardiovascular disorders. Also, endothelial dysfunction plays an essential role in the development of atherosclerosis. We aimed to evaluate the effects of thyroid-stimulating hormone (TSH) on pro-inflammatory tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), angiogenic vascular endothelial growth factor (VEGF) and leukocyte adhesion, intercellular adhesion molecule 1 (ICAM-1) and E-selectin in human umbilical vein endothelial cells (HUVECs). In this study, HUVEC cells were treated with 1 and 2 μM of TSH in different treatment times. The gene and protein expression of ICAM-1, VEGF, and E-selectin were performed by real-time polymerase chain reaction and western blotting, respectively. Likewise, TNF-α and IL-6 protein levels were determined by the ELISA method. VEGF, ICAM-1, and E-selectin as endothelial dysfunction markers and also, TNF-α and IL-6 as pro-inflammatory cytokines were detectable in HUVEC. Besides, the results of this study revealed that TSH treatment down-regulates TNF-α and IL-6. Evaluating the gene and protein expression data revealed the upregulation of ICAM-1, E-selectin, and VEGF in TSH treated cases in different periods of exposure. Considering the multiple actions of TSH, it could be concluded that TSH plays a controversial role in atherogenesis by anti-inflammatory effects and on the other side, angiogenesis and leukocyte adhesion induction which is related to vascular cell proliferation.

Higher free triiodothyronine concentration is associated with lower prevalence of microangiopathic complications and better metabolic control in adult euthyroid people with type 1 diabetes

PURPOSE

Type 1 diabetes mellitus (T1DM) is a disorder of insulin deficiency but with a wide range of hormones simultaneously disturbed. The study was performed to explore relation of free triiodothyronine (FT3) with metabolic control and occurrence of microangiopathic complications.

METHODS

A total of 266 adult T1DM participants [56% men; 32 (interquartile range, IQR: 25-39) years and disease duration 13 (IQR: 8-19) years] in euthyroid state with negative history for hypothyroidism were included to the study. Participants were screened for thyroid-stimulating hormone (TSH), free thyroxine (FT4) and FT3. Moreover, microangiopathic complications (retinopathy, diabetic kidney disease, peripheral and autonomic neuropathy), markers of metabolic control such as glycated hemoglobin (HbA_1c) were evaluated.

RESULTS

A total of 114 (42.9%) people had diagnosed at least one microangiopathic complication. In multivariable linear regression higher HbA_1c was statistically significant independent predictor of lower FT3 (β = -0.25; p < 0.0001) after adjustment for sex, T1DM duration, HbA_1c, waist-to-hip ratio (WHR) (R² = 0.15, p < 0.0001). Higher FT3 was simultaneously a predictor of lower prevalence of microangiopathy in multivariate logistic regression analysis (odds ratio, 0.51; 95% confidence interval, 0.27-0.98; p = 0.04) after an adjustment for: age, hypertension, HbA_1c, WHR and total cholesterol (TC).

CONCLUSIONS

FT3 as tissue active hormone plays a clinically important role in T1DM people. The higher FT3 concentration is related to the lower prevalence of microangiopathy and better metabolic control of the disease in adult euthyroid people with T1DM.

New Interfaces of Thyroid Hormone Actions With Blood Coagulation and Thrombosis

Substantial clinical evidence indicates hyperthyroidism enhances coagulation and increases the risk of thrombosis. In vitro and clinical evidence implicate multiple mechanisms for this risk. Genomic actions of thyroid hormone as 3,5,3′-triiodo-L-thyronine (T₃) via a nuclear thyroid hormone receptor have been implicated, but recent evidence shows that nongenomic mechanisms initiated at the receptor for L-thyroxine (T₄) on platelet integrin αvβ3 are prothrombotic. The T₄-initiated mechanisms involve platelet activation and, in addition, cellular production of cytokines and chemokines such as CX3CL1 with procoagulatory activities. These procoagulant actions of T₄ are particulary of note because within cells T4 is not seen to be functional, but to be only a prohormone for T₃. Finally, it is also possible that thyroid hormone stimulates platelet-endothelial cell interaction involved in local thrombus generation. In this brief review, we survey mechanisms by which thyroid hormone is involved in coagulation and platelet functions. It is suggested that the threshold should be lowered for considering the possibility that clinically significant clotting may complicate hyperthyroidism. The value of routine measurement of partial thromboplastin time or circulating D-dimer in patients with hyperthyroid or in patients treated with thyrotropin-suppressing dosage of T₄ requires clinical testing.

Blocking mitochondrial cyclophilin D ameliorates TSH-impaired defensive barrier of artery

AIMS

Endothelial cells (ECs) constitute the defensive barrier of vasculature, which maintains the vascular homeostasis. Mitochondrial oxidative stress (mitoOS) in ECs significantly affects the initiation and progression of vascular diseases. The higher serum thyroid stimulating hormone (TSH) level is being recognized as a nonconventional risk factor responsible for the increased risk of cardiovascular diseases in subclinical hypothyroidism (SCH). However, effects and underlying mechanisms of elevated TSH on ECs are still ambiguous. We sought to investigate whether cyclophilin D (CypD), emerging as a crucial mediator in mitoOS, regulates effects of TSH on ECs.

METHODS AND RESULTS

SCH patients with TSH > = 10mIU/L showed a positive correlation between serum TSH and endothelin-1 levels. When TSH levels declined to normal in these subjects after levothyroxine therapy, serum endothelin-1 levels were significantly reduced. Supplemented with exogenous thyroxine to keep normal thyroid hormones, thyroid-specific TSH receptor (TSHR)-knockout mice with injection of exogenous TSH exhibited elevated serum TSH levels, significant endothelial oxidative injuries and disturbed endothelium-dependent vasodilation. However, Tshr-/- mice resisted to TSH-impaired vasotonia. We further confirmed that elevated TSH triggered excessive mitochondrial permeability transition pore (mPTP) opening and mitochondrial oxidative damages in mouse aorta, as well as in cultured ECs. Genetic or pharmacological inhibition of CypD (the key regulator for mPTP opening) attenuated TSH-induced mitochondrial oxidative damages and further rescued endothelial functions. Finally, we confirmed that elevated TSH could activate CypD by enhancing CypD acetylation via inhibiting adenosine monophosphate-activated protein kinase/sirtuin-3 signaling pathway in ECs.

CONCLUSIONS

These findings reveal that elevated TSH triggers mitochondrial perturbations in ECs and provide insights that blocking mitochondrial CypD enhances the defensive ability of ECs under TSH exposure.

VEGFR2 but not VEGFR3 governs integrity and remodeling of thyroid angiofollicular unit in normal state and during goitrogenesis

Thyroid gland vasculature has a distinguishable characteristic of endothelial fenestrae, a critical component for proper molecular transport. However, the signaling pathway that critically governs the maintenance of thyroid vascular integrity, including endothelial fenestrae, is poorly understood. Here, we found profound and distinct expression of follicular epithelial VEGF‐A and vascular VEGFR2 that were precisely regulated by circulating thyrotropin, while there were no meaningful expression of angiopoietin–Tie2 system in the thyroid gland. Our genetic depletion experiments revealed that VEGFR2, but not VEGFR3, is indispensable for maintenance of thyroid vascular integrity. Notably, blockade of VEGF‐A or VEGFR2 not only abrogated vascular remodeling but also inhibited follicular hypertrophy, which led to the reduction of thyroid weights during goitrogenesis. Importantly, VEGFR2 blockade alone was sufficient to cause a reduction of endothelial fenestrae with decreases in thyrotropin‐responsive genes in goitrogen‐fed thyroids. Collectively, these findings establish follicular VEGF‐A–vascular VEGFR2 axis as a main regulator for thyrotropin‐dependent thyroid angiofollicular remodeling and goitrogenesis.

Association Between Thyroid Hormones, Thyroid Antibodies, and Cardiometabolic Factors in Non-Obese Individuals With Normal Thyroid Function

BACKGROUND

Hypothyroidism is an important risk factor for cardiovascular diseases, and autoimmune thyroiditis (AIT) is the leading cause of hypothyroidism. Recent studies showed that even AIT patients with euthyroidism still had an increased number of early atherosclerotic lesions. However, the precise mechanism is not yet known. This study aimed to investigate the association of thyroid function, thyroid autoimmunity, and cardiometabolic risk factors in non-obese AIT patients with euthyroidism.

METHODS

A total of 5,608 non-obese individuals including 1,402 AIT patient and 4,206 sex-, age-, and body mass index (BMI)-matched healthy controls were recruited.

RESULTS

The AIT patients had significantly lower free T3 and free T4 levels, and higher TSH, antithyroid peroxidase antibodies (TPOAb) and TgAb levels. The elevated levels of high sensitivity C reactive protein (hsCRP) and homeostasis model assessment of insulin resistance (HOMA-IR) were observed in the AIT patients than the controls [hsCRP: 0.65 (0.27-1.33) vs. 0.20 (0.03-0.74) mg/L; HOMA-IR: 2.78 ± 1.60 vs. 2.33 ± 1.49; all P < 0.05]. Thyroid function was not associated with metabolic parameters and inflammatory makers, while the TPOAb titer was positively associated with the HOMA-IR and hsCRP levels after adjustment for confounding factors (all P < 0.05). Multivariate regression analysis demonstrated that the TPOAb level was an independent influencing factor for the HOMA-IR and hsCRP levels (HOMA-IR: β = 0.058, P < 0.05; hsCRP: β = 0.108, P < 0.05).

CONCLUSION

The TPOAb level is associated with HOMA-IR and hsCRP levels independently of thyroid function in non-obese individuals. Mild deviation of thyroid function within the normal range, chronic inflammation, and insulin resistance may be the links between AIT and atherosclerosis in the non-obese population.

Thyrotropin Regulates eNOS Expression in the Endothelium by PGRN Through Akt Pathway

To investigate the expression of endothelial nitric oxide synthase (eNOS) and nitric oxide (NO) in the aorta of subclinical hypothyroidism (SCH) rat model. The mechanisms underlying thyrotropin (TSH) affecting eNOS and PGRN expression in human umbilical vein endothelial cells (HUVECs) cultured in vitro were investigated. In the current study, SCH rat models were established by the administration of L-T₄ injection after thyroidectomy in Wistar rats, as opposed to that in the normal and clinical hypothyroidism (CH) groups. The concentrations of NO (pmol/μL) in the SCH and CH groups were significantly lower than that in the normal group (40.8 ± 7.6 and 32.9 ± 10.8 vs. 51.2 ± 12.1, P < 0.05). However, the expression level of eNOS is increased significantly (P < 0.05) in both SCH and CH groups; a similar result was observed for the PGRN protein. In cultured HUVECs, TSH can also up-regulate the expression of eNOS; however, it is accompanied by a reduced concentration of NO and increased level of superoxide anion, thereby indicating uncoupled eNOS. As eNOS is increased, we found that Akt in HUVECs were upregulated by TSH, as well as PGRN expression. While inhibiting the expression of PGRN in HUVECs using siRNA, the expression of eNOS, as well as Akt were also inhibited. In conclusion, SCH can induce vascular endothelial dysfunction in rats, and PGRN participated in the process of TSH-induced expression of Akt/eNOS in the endothelium.

Triiodothyronine differentially modulates the LH and FSH synthesis and secretion in male rats

Hypothyroidism and thyrotoxicosis produce adverse effects in male reproduction by unknown mechanisms. We investigated whether triiodothyronine (T3) modulates luteinizing hormone (LH) and follicle stimulating hormone (FSH) synthesis/secretion, by inducing different thyroid states. In hypothyroidism, the content of Lhb and Fshb mRNAs was increased, while their association to ribosomes and the protein content were reduced and the serum LH and FSH concentrations were augmented and decreased, respectively. Thyrotoxicosis reduced Lhb mRNA and LH serum concentration, and increased Lhb mRNA translational rate. The Fshb mRNA content and its association to ribosomes were also increased, whereas FSH serum concentrations were comparable to euthyroid levels. Acute T3 treatment decreased the total content of Lhb and Fshb mRNAs, and increased their association to ribosomes, as well as the LHB and FSHB contents in secretory granules. This study shows that T3 acts on gonadotrophs, resulting in direct effects on LH and FSH synthesis/secretion of male rats, suggesting that some reproductive disorders observed in men may be associated with thyroid hormone imbalances.

Effect of levothyroxine on the progression of carotid intima-media thickness in subclinical hypothyroidism patients: a meta-analysis

BACKGROUND

Subclinical hypothyroidism (SCH) has been associated with increased carotid intima-media thickness (C-IMT) in recent studies, but the effects of levothyroxine (L-T4) therapy on C-IMT in SCH patients are still controversial.

AIM

To evaluate the effect of L-T4 therapy on endothelial function as determined by C-IMT in patients with SCH.

METHODS

BeforeJuly 2016, we searched the PubMed, Embase, Cochrane Library and Google Scholar databases, selecting published randomised controlled trials (RCTs) and self-controlled trials for the meta-analysis.

RESULTS

Three RCTs with 117 patients were considered appropriate for the meta-analysis. The results of the meta-analysis indicated that L-T4 significantly decreased the development of C-IMT (weighted mean difference (WMD) -0.05 mm, 95% CI -0.08 to -0.01 mm; p=0.025). We also analysed nine studies (self-controlled trials) with 247 patients and extracted the IMT of SCH patients before and after L-T4 treatment. After L-T4 therapy, the pooled estimate of the WMD of decreased C-IMT was -0.04 mm (95% CI -0.07 to -0.02 mm; p=0.05). Subgroup analysis showed that L-T4 therapy was associated with a decrease in C-IMT among patients of mixed genders (WMD -0.03 mm, 95% CI -0.06 to -0.01 mm; p=0.145). L-T4 therapy was associated with a decrease in C-IMT among female patients (WMD -0.07 mm, 95% CI -0.14 to -0.01; p=0.186). Longer treatment (>6 months) also resulted in a significant decrease in C-IMT (WMD -0.05 mm, 95% CI -0.08 to -0.02; p=0.335).

CONCLUSION

This meta-analysis indicates that L-T4 treatment of SCH patients can reduce C-IMT, possibly as a result of the reduction of total cholesterol, triglyceride, low density lipoprotein, systolic blood pressure, diastolic blood pressure, lipoprotein(a), and flow-mediated dilatation. Decreased C-IMT was observed in SCH patients after long-term (>6 months) L-T4 treatment. RCTs with larger samples are needed to verify these observations.

High Thyroid-stimulating Hormone Levels Increase Proinflammatory and Cardiovascular Markers in Patients with Extreme Obesity

BACKGROUND AND AIMS

Obesity is an important health problem worldwide and many studies have suggested a relationship between obesity and thyroid function, with controversial results. Interestingly, high TSH levels have been involved with the presence of inflammatory state and risk for developing cardiovascular diseases in hypothyroid and obese patients. The aim in this work was to determine the prevalence of hypothyroidism in patients with extreme obesity and to determine whether their TSH levels were related to increased serum levels of inflammatory and cardiovascular markers.

METHODS

A cross-sectional study in 101 patients with extreme obesity (BMI ≥40) was performed. Anthropometric (weight, height and waist circumference) and biochemical (fasting glucose, glycosylated hemoglobin, triglycerides, total cholesterol, LDL-C, HDL-C and insulin) parameters were measured. TSH and FT4 levels as well as clinical exploration for diagnosis of hypothyroidism were carried out. Serum concentration of IL-10, IL-6, adiponectin, resistin, leptin, ICAM-1, VCAM-1 and E-selectin were determined.

RESULTS

A high prevalence for diabetes (37.6%), prediabetes (50.5%), dyslipidemia (74.3%), hypertension (61.4%) and hypothyroidism (48.5%) was observed in patients with extreme obesity. The presence of hypothyroidism increased serum concentration of proinflammatory cytokines IL-6 and leptin and decreased the antiinflammatory cytokine adiponectin. In addition, serum TSH levels showed a correlation for waist circumference, weight, BMI, A1c, insulin, IL-6, leptin, ICAM-1 and E-selectin.

CONCLUSION

There is a high prevalence for hypothyroidism in patients with extreme obesity. High levels of TSH contribute to elevate proinflammatory and cardiovascular risk markers, increasing the risk for development of cardiovascular diseases.

Effect of Thyrotropin on Osteopontin, Integrin αvβ3, and VCAM-1 in the Endothelium via Activation of Akt

Numerous epidemiological studies have shown that subclinical hypothyroidism (SCH) can impair endothelial function and cause dyslipidemia. Studies have evaluated the effects of thyroid stimulating hormone (TSH) on endothelial cells, but the mechanism underlying the proatherosclerotic effect of increased TSH levels remains unclear. In the present study, SCH rat models were established in thyroidectomized Wistar rats that were given l-T₄ daily. The results showed that in vivo, the expression of osteopontin (OPN) vascular cell adhesion molecule (VCAM-1), and levels of integrin α_vβ₃ in the aortic tissue in SCH and Hypothyroidism (CH) groups was higher than in the control group. However, the effect in the SCH group was higher than in the CH group. In vitro, results showed that different concentration and time gradients of TSH stimulation could increase the expression of OPN, VCAM-1, and integrin α_vβ₃, and this was accompanied by extracellular signal regulated kinase 1/2 (Erk1/2) and Akt activation in human umbilical vein endothelial cells (HUVECs). TSH induced elevation of these proatherosclerotic factors was partially suppressed by a specific Akt inhibitor but not by a specific Erk inhibitor. Findings suggested that the endothelial dysfunction caused by SCH was related to increased proatherosclerotic factors induced by TSH via Akt activation.

Subclinical Hypothyroidism - What is Responsible for its Association with Cardiovascular Disease?

Subclinical hypothyroidism (SH) is a common condition, with prevalence estimates ranging from 4–20%, depending on the population demographics. Although epidemiological analysis associates it with an increased risk of cardiovascular disease, clinical practice guidelines express uncertainty about whether to monitor or to treat. As we await large-scale, well-designed randomised clinical trials regarding treatment of SH, a review of pathophysiological considerations may be informative to better understand this disorder.

Levothyroxine but Not Selenium Increases Endothelial Progenitor Cell Counts in Patients with Hypothyroidism

BACKGROUND

Hypothyroidism is a common endocrine disease associated with increased oxidative stress, increased cardiovascular (CV) risk, CV events and endothelial dysfunction. Endothelial progenitor cells (EPCs) are a well-known marker of CV risk.

OBJECTIVE

The aim of this work was to ascertain whether hypothyroidism is associated with lower EPC counts and if treatment with levothyroxine (LT4) or selenium (Se) improves EPC counts compared to placebo.

METHODS

Hypothyrod patients (n = 100) were randomly divided into five groups to receive placebo (group A), LT4 (group B) or Se at doses of 83 µg (group C), 166 µg (group D) or 249 µg (group E) for 3 months. Each group comprised 20 patients: 10 with 'mild' hypothyroidism and 10 with 'severe' hypothyroidism. A healthy control group (group F) with 20 euthyroid subjects was also recruited. Subjects had to be free of CV disease, diabetes and drugs that interfere with EPCs. Anthropometric measurements (height, weight, BMI), blood pressure, fasting lipids and EPC analyses were performed at baseline and after 3 months.

RESULTS

EPC counts were significantly lower in hypothyroid patients compared to controls. EPCs increased after 3 months of treatment with LT4, but not with Se at any dosage. CD133+ and CD34+ EPC counts were negatively correlated with thyroid-stimulating hormone (TSH; r (2) = 0.523, p < 0.01 and r (2) = 0.517, p < 0.01, respectively) and positively correlated with FT4 (r (2) = 0.394, p < 0.01 and r (2) = 0.369, p < 0.01, respectively). TSH and FT4 were the only predictors of EPC counts.

CONCLUSIONS

Hypothyroidism is associated with low EPC counts. Treatment with LT4, but not Se, can improve EPC counts.

Thyroxine therapy ameliorates serum levels of eicosanoids in Chinese subclinical hypothyroidism patients

AIM

The eicosanoids derived from phospholipids play key roles in inflammation. However, the profiles of serum eicosanoids in subclinical hypothyroidism (SH) patients and the effects of thyroxine replacement therapy (TRT) on these eicosanoids remain unclear. Many studies show that TSH regulates lipid metabolism. As eicosanoids derived from phospholipids play key roles in oxidative stress and immune function and inflammatory process, it was necessary to explore the profiles of serum eicosanoids in SH patients and the effects of thyroxine replacement therapy (TRT) on the eicosanoids.

METHODS

A total of 50 Chinese SH patients and 22 healthy volunteers were recruited. SH patients received TRT (L-T4, 25 and 50 mcg/d for patients with TSH≤10.0 mIU/L and TSH>10.0 mIU/L, respectively) for 3 months. Serum levels of major eicosanoids and cPLA2 were analyzed using LC-MS and clinical biochemical assays.

RESULTS

The serum levels of cPLA2, eicosanoids (8-isoPGF2a, 11-dehydroTXB2 and 12-HETE) and 11-dehydroTXB2/6-Keto-PGF1a were significantly elevated in SH patients. The serum TSH levels were significantly correlated with the levels of cPLA2 (r=+0.65), 11-dehydroTXB2 (r=+0.32) and 11-dehydroTXB2/6-Keto-PGF1a (r=+0.37). After 3-month TRT, the serum levels of TSH, cPLA2 and the above-mentioned eicosanoids in SH patients were significantly decreased.

CONCLUSION

The metabolism of eicosanoids is significantly altered in Chinese SH patients, and TRT can ameliorate the abnormalities of serum eicosanoid levels.

MECHANISMS IN ENDOCRINOLOGY: Impact of isolated TSH levels in and out of normal range on different tissues

Routine treatment of thyroid cancer (TC) includes long-term suppression of TSH. The necessity of this treatment in low- and intermediate-risk patients as well as the extent of TSH suppression is currently under discussion. A literature search was performed to illustrate the role of TSH in extrathyroidal cells and to identify potential reasons for different effects of exogenously suppressed and endogenously low TSH levels. Although adverse effects of subnormal and supranormal TSH blood levels on heart and brain have not been consistently found, studies show a clear negative effect of suppressed TSH levels on bone mineral density. Experimental data also support an important role of TSH in the immune system. The ability of levothyroxine (l-T4) to regulate TSH levels and triiodothyronine levels in a physiological manner is limited. Reduction of circadian changes in TSH levels, decrease of thyroid hormone-binding proteins, prevention of potential compensatory increases of TSH levels (e.g., in old age), and unresponsiveness of TSH-producing cells to TRH on l-T4 treatment might cause adverse effects of suppressed TSH levels. In view of the adverse effects of aggressive TSH suppression, achieving the suggested levels of TSH between 0.9 and 1 mU/l in the treatment of low-to-intermediate risk TC patients appears justified.

Clinical outcomes of patients with hypothyroidism undergoing percutaneous coronary intervention

AIMS

The aim of this study was to investigate the association between hypothyroidism and major adverse cardiovascular and cerebral events (MACCE) in patients undergoing percutaneous coronary intervention (PCI).

METHODS AND RESULTS

Two thousand four hundred and thirty patients who underwent PCI were included. Subjects were divided into two groups: hypothyroidism (n = 686) defined either as a history of hypothyroidism or thyroid-stimulating hormone (TSH) ≥5.0 mU/mL, and euthyroidism (n = 1744) defined as no history of hypothyroidism and/or 0.3 mU/mL ≤ TSH < 5.0 mU/mL. Patients with hypothyroidism were further categorized as untreated (n = 193), or those taking thyroid replacement therapy (TRT) with adequate replacement (0.3 mU/mL ≤ TSH < 5.0 mU/mL, n = 175) or inadequate replacement (TSH ≥ 5.0 mU/mL, n = 318). Adjusted hazard ratios (HRs) were calculated using Cox proportional hazards models. Median follow-up was 3.0 years (interquartile range, 0.5-7.0). After adjustment for covariates, the risk of MACCE and its constituent parts was higher in patients with hypothyroidism compared with those with euthyroidism (MACCE: HR: 1.28, P = 0.0001; myocardial infarction (MI): HR: 1.25, P = 0.037; heart failure: HR: 1.46, P = 0.004; revascularization: HR: 1.26, P = 0.0008; stroke: HR: 1.62, P = 0.04). Compared with untreated patients or those with inadequate replacement, adequately treated hypothyroid patients had a lower risk of MACCE (HR: 0.69, P = 0.005; HR: 0.78, P = 0.045), cardiac death (HR: 0.43, P = 0.008), MI (HR: 0.50, P = 0.0004; HR: 0.60, P = 0.02), and heart failure (HR: 0.50, P = 0.02; HR: 0.52, P = 0.017).

CONCLUSION

Hypothyroidism is associated with a higher incidence of MACCE compared with euthyroidism in patients undergoing PCI. Maintaining adequate control on TRT is beneficial in preventing MACCE.

Pattern of circulating endothelial-derived microparticles among chronic heart failure patients with dysmetabolic comorbidities: The impact of subclinical hypothyroidism

The study aim was to evaluate the impact of dysmetabolic comorbidities including subclinical hypothyroidism (SH) on pattern of circulating endothelial-derived microparticles (EMPs) in chronic heart failure (CHF) patients.

METHODS

It was retrospectively involved a cohort of 388 patients with CHF. Fifty three CHF subjects had SH and 335 patients were free from thyroid dysfunction. Circulating levels of NT-pro brain natriuretic peptide (NT-pro-BNP), high-sensitivity C-reactive protein (hs-CRP), thyroid stimulating hormone (TSH), total and free thyroxine (T4) and triiodothyronine (T3) EMPs were measured at baseline. SH was defined per contemporary clinical guideline as state associated with elevated level of serum TSH>10 μU/L and basal normal free T3 and T4 concentration.

RESULTS

Circulating CD31+/annexin V+ EMPs were higher in SH patients compared with none SH subjects. In contrast, activated CD62E+ EMP numbers were not significantly different between both patient cohorts. Using C-statistics for Models with TSH, New York Heart Association (NYHA) class, dyslipidemia, and circulating biomarkers (hs-CRP, NT-proBNP, serum uric acid) as Continuous Variables we found that adding of NYHA class alone, NT-proBNP alone or their combination to the based model (TSH) improved the relative integrated discrimination improvement (IDI) for increased CD31+/annexin V+ to CD62E+ ratio by 4.9%; 9.2% and 9.6% respectively. NT-proBNP improves significantly predictive model based on TSH for increased CD31+/annexin V+ to CD62E+ ratio. Among patient study population for category-free net reclassification improvement (NRI), 4% of events (P=0.026) and 6% of non-events (P=0.012) were correctly reclassified by the addition of circulating NT-proBNP to the base model (TSH) for Increased CD31+/annexin V+ to CD62E+ ratio. Therefore, 4% of events (P=0.028) and 5% of non-events (P=0.014) were correctly reclassified using category-free NRI for increased CD31+/annexin V+ to CD62E+ ratio.

CONCLUSION

We found that SH state in CHF patients associates with impaired pattern of circulating EMPs with predominantly increased number of apoptotic-derived microparticles.

The Association of Subclinical Hypothyroidism and Pattern of Circulating Endothelial-Derived Microparticles Among Chronic Heart Failure Patients

Background:

Subclinical hypothyroidism (SH) is diagnosed biochemically by the presence of normal serum free thyroxine concentration, in conjunction with an elevated serum thyroid-stimulating hormone level. Recent studies have demonstrated the frequent association between SH and cardiovascular diseases and risk factors.

Objectives:

To evaluate the impact of SH on patterns of circulating endothelial-derived microparticles, (EMPs) among chronic heart failure (CHF) patients

Patients and Methods:

This is a retrospective study involving a cohort of 388 patients with CHF. Fifty-three CHF subjects had SH and 335 patients were free from thyroid dysfunction. Circulating levels of N-terminal-pro brain natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hs-CRP), thyroid-stimulating hormone (TSH), total and free thyroxine (T4), and triiodothyronine (T3), and endothelial apoptotic microparticles (EMPs), were measured at baseline. SH was defined, according to contemporary clinical guidelines, as a biochemical state associated with an elevated serum TSH level of greater 10 μU/L and normal basal free T3 and T4 concentrations.

Results:

Circulating CD31+/annexin V+ EMPs were higher in patients with SH compared to those without SH. In contrast, activated CD62E+ EMP numbers were not significantly different between both patient cohorts. Using uni (bi) variate and multivariate age- and gender-adjusted regression analysis, we found several predictors that affected the increase of the CD31+/annexin V+ to CD62E+ ratio in the patient study population. The independent impact of TSH per 6.5 μU/L (odds ratio [OR] = 1.23, P = 0.001), SH (OR = 1.22, P = 0.001), NT-proBNP (OR = 1.19, P = 0.001), NYHA class (OR = 1.09, P = 0.001), hs-CRP per 4.50 mg/L (OR = 1.05, P = 0.001), dyslipidemia (OR = 1.06, P = 0.001), serum uric acid per 9.5 mmol/L (OR = 1.04, P = 0.022) on the increase in the CD31+/annexin V+ to CD62E+ ratio, was determined.

Conclusions:

We believe that the SH state in CHF patients may be associated with the impaired pattern of circulating EMPs, with the predominantly increased number of apoptotic-derived microparticles.

Endothelial Functioning and Hemodynamic Parameters in Rats with Subclinical Hypothyroid and the Effects of Thyroxine Replacement

OBJECTIVE

Subclinical hypothyroidism (SCH) and its associations with atherosclerosis (AS) and cardiovascular disease remain controversial. The purpose of our study was to observe changes in endothelial functioning and hemodynamics in rats with SCH and to determine whether L-thyroxine (L-T4) administration affects these changes.

METHODS

In total, sixty male Wistar rats were randomly divided into the following three groups with 20 rats each: control euthyroid rats, SCH rats and SCH rats that had been treated with thyroxine (SCH+T4). The SCH rats were induced by administration of 10 mg x kg(-1) x d(-1) methimazole (MMI) once daily by gavage for 3 months. The SCH+T4 rats were administered the same dose of MMI for three months in addition to 2 μg x kg(-1) x d(-1) L-T4 once daily by gavage after 45 days of MMI administration. The control rats received physiological saline via gavage.

RESULTS

The SCH group had significantly higher thyroid-stimulating hormone (TSH), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and endothelin (ET) levels and a lower nitric oxide (NO) level than the control and SCH+T4 groups. The tail and carotid artery blood pressures, left ventricular systolic pressure, heart rate and aorta ventralis blood flow were significantly lower in the SCH group than in the control and SCH+T4 groups. ACH treatment caused concentration-dependent relaxation, which was reduced in the SCH arteries compared with the control and SCH+T4 arteries. Histopathological examination revealed the absence of pathological changes in the SCH rat arteries.

CONCLUSIONS

These findings demonstrate that L-T4 treatment ameliorates endothelial dysfunction and hemodynamic changes in SCH rats.

Mechanism of subclinical hypothyroidism accelerating endothelial dysfunction (Review)

The association between subclinical hypothyroidism (SH) and cardiovascular disease has received increasing attention in recent years. The predisposition of patients with SH to endothelial dysfunction, an early sign of atherosclerosis, has been observed. This predisposition may be partially explained by the factors also found in patients with SH, including changes in lipid profile, low grade chronic inflammation, oxidative stress and insulin resistance. The proportional risks of endothelial dysfunction to thyroid stimulating hormone (TSH) also indicate that the action of TSH on extra thyroidal-stimulating hormone receptor (TSHR) is a possible mechanism underlying the correlation, which has later been supported by the associated basic studies. L-thyroxine replacement therapy appears to improve the aforementioned aspects, whereas there remain certain controversies, particularly for the elderly. Thus, more study data are required to confirm the benefit of L-thyroxine treatment for patients with SH.