Risk of coronary heart disease and mortality for adults with subclinical hypothyroidism

Estimation of left ventricular functions in patients with subclinical hypothyroidism: a meta-analysis

Objective

To evaluate left ventricular (LV) function in patients with subclinical hypothyroidism (ScH) compared to healthy individuals and to provide clinical hints for practitioners.

Methods

PubMed, Embase, Cochrane Library, and Web of Science were systematically searched in this meta-analysis. Studies evaluating LV function in ScH patients were included. Standardized mean difference (SMD) and the 95% confidence intervals (CIs) were calculated as effect size. Heterogeneity and risks of bias of included studies were assessed.

Results

A total of 9 studies were identified as eligible. The SMD for fractional shortening (FS, %) was -0.21 (95% CI: -0.60, 0.17; z = -1.08, p = 0.2788). The pooled SMD for systemic vascular resistance (SVR, dynes/sec·cm-5) was -0.41 (95% CI: -1.31, 0.49; z = -0.89, p = 0.3744). The pooled SMD for early diastolic mitral flow velocity/late diastolic mitral flow velocity (E/A) ratio was -0.74 (95% CI: -1.09, -0.39; z = -4.13, p < 0.001). The pooled SMD for ejection fraction (EF, %) was -0.35 (95% CI: -0.59, -0.12; z = -2.95, p = 0.0032).

Conclusion

ScH patients had significantly worse LV function parameters than healthy controls. These changes in LV function may be involved in the management of ScH.

Relationship between plasma glutamate and cardiovascular disease risk in Chinese patients with type 2 diabetes mellitus by gender

Objectives

This study aimed to assess the association between plasma glutamate (Glu) and the risk of cardiovascular disease (CVD) in patients with type 2 diabetes mellitus (T2DM) and whether this association differs by gender.

Material and methods

We retrieved clinical information on 1032 consecutive patients with T2DM from a same tertiary care center from May 2015 to August 2016. Glu was quantified by liquid chromatography-tandem mass spectrometry analysis. Glu was converted into a categorical variable based on the median concentration in the whole population, while logistic regression was used to obtain the odds ratio (OR) and 95% confidence interval (CI), and the correlation between Glu and various biochemical indices was analyzed.

Results

We found that Glu was positively associated with the risk of CVD in patients with T2DM. This correlation was more significant in women. In T2DM patients, the higher the age, body mass index (BMI), weight and systolic blood pressure (SBP), the lower the glycosylated hemoglobin (HbA1C) concentration and the higher the Glu. In female patients, the correlation between age, weight, BMI, SBP, and plasma Triglycerides (TG), and Glu was also statistically significant.

Conclusion

In conclusion, female T2DM patients with high levels of Glu have a higher risk of developing CVD.

Minor perturbations of thyroid homeostasis and major cardiovascular endpoints—Physiological mechanisms and clinical evidence

It is well established that thyroid dysfunction is linked to an increased risk of cardiovascular morbidity and mortality. The pleiotropic action of thyroid hormones strongly impacts the cardiovascular system and affects both the generation of the normal heart rhythm and arrhythmia. A meta-analysis of published evidence suggests a positive association of FT4 concentration with major adverse cardiovascular end points (MACE), but this association only partially extends to TSH. The risk for cardiovascular death is increased in both subclinical hypothyroidism and subclinical thyrotoxicosis. Several published studies found associations of TSH and FT4 concentrations, respectively, with major cardiovascular endpoints. Both reduced and elevated TSH concentrations predict the cardiovascular risk, and this association extends to TSH gradients within the reference range. Likewise, increased FT4 concentrations, but high-normal FT4 within its reference range as well, herald a poor outcome. These observations translate to a monotonic and sensitive effect of FT4 and a U-shaped relationship between TSH and cardiovascular risk. Up to now, the pathophysiological mechanism of this complex pattern of association is poorly understood. Integrating the available evidence suggests a dual etiology of elevated FT4 concentration, comprising both ensuing primary hypothyroidism and a raised set point of thyroid function, e. g. in the context of psychiatric disease, chronic stress and type 2 allostatic load. Addressing the association between thyroid homeostasis and cardiovascular diseases from a systems perspective could pave the way to new directions of research and a more personalized approach to the treatment of patients with cardiovascular risk.

Thyroid Function in Adults with Prader-Willi Syndrome; a Cohort Study and Literature Review

Prader–Willi syndrome (PWS) is a complex genetic syndrome combining hypotonia, hyperphagia, a PWS-specific neurocognitive phenotype, and pituitary hormone deficiencies, including hypothyroidism. The low muscle mass associated with PWS causes a low energy expenditure due to a low basal metabolic rate. Combined with increased energy intake due to hyperphagia, this results in a high risk of obesity and associated cardiovascular disease. To reduce the high mortality in PWS (3% yearly), exercise is extremely important. As hypothyroidism can impair exercise tolerance, early detection is crucial. We performed a literature search for articles on hypothyroidism in PWS, measured thyroid hormone (TH) levels in 122 adults with PWS, and performed a medical file search for medication use. Hypothyroidism (low free thyroxin) was present in 17%, and often central in origin (80%). Triiodothyronine levels were lower in patients who used psychotropic drugs, while other TH levels were similar. One in six patients in our cohort of adults with PWS had hypothyroidism, which is more than in non-PWS adults (3%). We recommend yearly screening of free thyroxin and thyroid-stimulating hormone levels to avoid the negative effects of untreated hypothyroidism on basal metabolic rate, body mass index, and cardiovascular risk. Additionally, we recommend measuring TH concentrations 3–4 months after the start of growth hormone treatment.

Evaluation of biochemical markers of kidney function in patients with subclinical hypothyroidism in comparison with euthyroid people

Background:

Subclinical hypothyroidism (SCH) as a compensated or preclinical type of primary and overt hypothyroidism (OHT) can affect approximately 4–10% of the general population. Treating SCH can slowdown the progression to OHT, the formation of cardiovascular diseases, neuropsychiatric symptoms, and other miscellaneous problems.

Materials and Methods:

The present study is a case-control study that was conducted on 239 adults who were referred to 501 Imam Reza Hospital from March 2019 up to September 2019. Of the 239 patients and their families admitted to the hospital, 121 (50.6%) were euthyroid (as control group) and the remaining participants (118, 49.4%) were SCH (as case group). The serum levels of thyroid stimulating hormone (TSH), urea, uric acid, creatinine, T3, and T4 were asked to be determined at a single laboratory. Biochemical markers of kidney function and the level of thyroid hormones were compared between the two groups of euthyroid and SCH.

Results:

TSH was significantly higher in SCH (7.25 (4.4-18.15)) compared to euthyroid (1.4 (0.2-3.7)) patients (P < 0.001). Among biochemical markers, creatinine (P < 0.001) and uric acid (P = 0.006) had higher serum levels in the case group. There was no remarkable difference in the thyroxine hormone levels and urea between the euthyroid and SCH patients (P > 0.05). Within the SCH group, there was a significant positive correlation between TSH and the level of creatinine (P = 0.001, r = 0.302).

Conclusion:

Regular monitoring of the major function of the kidneys in patients with hypothyroidism and SCH can help early diagnosis of kidney dysfunction, thus increasing the chance of restoring normal kidney function.

Associations of multiple serum biomarkers and the risk of cardiovascular disease in China

BACKGROUND

Previous studies focus on one or several serum biomarkers and the risk of cardiovascular disease (CVD). This study aims to investigate the association of multiple serum biomarkers and the risk of CVD and evaluate the dose-relationship between a single serum metabolite and CVD.

METHODS

Our case-control study included 161 CVD and 160 non-CVD patients who had a physical examination in the same hospital. We used stratified analysis and cubic restricted analysis to investigate the dose-response relationship of individual serum biomarkers and the CVD incident. Moreover, to investigate serum biomarkers and CVD, we used elastic net regression and logistic regression to build a multi-biomarker model.

RESULTS

In a single serum biomarker model, we found serum FT4, T4. GLU, CREA, TG and LDL-c were positively associated with CVD. In the male group, serum T4, GLU and LDL-c were positively associated with CVD; and serum TG was positively associated with CVD in the female group. When patients ≤63 years old, serum T4, GLU, CREA and TG were positively associated with CVD, and serum TG and LDL-c were positively associated with CVD when patients > 63 years old. Moreover, serum GLU had nonlinearity relationship with CVD and serum TG and LDL-c had linearity association with CVD. Furthermore, we used elastic regression selecting 5 serum biomarkers (GLU, FT4, TG, HDL-c, LDL-c) which were independently associated with CVD incident and built multi-biomarker model. And the multi-biomarker model had much better sensitivity than single biomarker model.

CONCLUSION

The multi-biomarker model had much higher sensitivity than a single biomarker model for the prediction of CVD. Serum FT4, TG and LDL-c were positively associated with the risk of CVD in single and multiple serum biomarkers models, and serum TG and LDL-c had linearity relationship with CVD.

Relation of Gut Microbes and L-Thyroxine Through Altered Thyroxine Metabolism in Subclinical Hypothyroidism Subjects

Thyroxine metabolism is an important topic of pathogenesis research and treatment schedule of subclinical hypothyroidism (SCH). L-Thyroxine replacement therapy (LRT) is usually recommended for severe SCH patients only. Our previous studies reported that disordered serum lipid of mild SCH people could also benefit from LRT. However, the benefits were different among individuals, as shown by the variations in drug dosage that required to maintain thyroid-stimulating hormone (TSH) stability. Alternative pathways, such as sulfation and glucuronidation of iodothyronine, may play a role in thyroid hormones metabolism in peripheral tissues aside from thyroid. Conjugated thyroxine can be hydrolyzed and reused in tissues including gastrointestinal tract, in which gut microbiota are one of the most attractive physiological components. On this site, the roles of gut microbiota in thyroidal metabolism should be valued. In this study, a cross-sectional study was performed by analyzing 16S rDNA of gut microbiota in mild SCH patients treated with L-thyroxine or not. Subjects were divided by serum lipid level, L-thyroxine treatment, or L-thyroxine dosage, respectively. Relationship between gut microbiome and serum profile, L-thyroxine treatment, and dose were discussed. Other metabolic disorders such as type 2 diabetes and hypertension were also taken into consideration. It turned out that microbiome varied among individuals divided by dose and the increment of L-thyroxine but not by serum lipid profile. Relative abundance of certain species that were associated with thyroxine metabolism were found varied among different L-thyroxine doses although in relatively low abundance. Moreover, serum cholesterol may perform relevance effects with L-thyroxine in shaping microbiome. Our findings suggested that the differences in L-thyroxine dosage required to maintain TSH level stability, as well as the SCH development, which was displayed by the increased L-thyroxine doses in subsequent follow-up, had relationship with gut microbial composition. The reason may due to the differences in thyroxine metabolic capacity in gut. In addition, the metabolic similarity of iodothyronines and bile acid in gut also provides possibilities for the correlation between host's thyroxine and cholesterol levels. This study was registered with ClinicalTrials.gov as number NCT01848171.

The role of thyroid hormone in metabolism and metabolic syndrome

Metabolic syndrome (MetS) and thyroid dysfunction are common in clinical practice. The objectives of this review are to discuss some proposed mechanisms by which thyroid dysfunctions may lead to MetS, to describe the bidirectional relationship between thyroid hormones (THs) and adiposity and finally, to resume a list of recent studies in humans that evaluated possible associations between thyroid hormone status and MetS or its clinical components. Not solely THs, but also its metabolites regulate metabolic rate, influencing adiposity. The mechanisms enrolled are related to its direct effect on adenosine triphosphate (ATP) utilization, uncoupling synthesis of ATP, mitochondrial biogenesis, and its inotropic and chronotropic effects. THs also act controlling core body temperature, appetite, and sympathetic activity. In a bidirectional way, thyroid function is affected by adiposity. Leptin is one of the hallmarks, but the pro-inflammatory cytokines and also insulin resistance impact thyroid function and perhaps its structure. MetS development and weight gain have been positively associated with thyroid-stimulating hormone (TSH) in several studies. Adverse glucose metabolism may be related to hyperthyroidism, but also to reduction of thyroid function or higher serum TSH, as do abnormal serum triglyceride levels. Hypo- and hyperthyroidism have been related to higher blood pressure (BP), that may be consequence of genomic or nongenomic action of THs on the vasculature and in the heart. In summary, the interaction between THs and components of MetS is complex and not fully understood. More longitudinal studies controlling each of all confounding variables that interact with endpoints or exposure factors are still necessary.

The Association Between Serum Thyrotropin Within the Reference Range and Metabolic Syndrome in a Community-Based Chinese Population

PURPOSE

We aimed to ascertain the association between thyrotropin (TSH) levels in euthyroid state and the prevalence of metabolic syndrome (MetS) in a community-based Chinese population.

PARTICIPANTS AND METHODS

Based on a large and well-characterized community cohort in Beijing, China, 1831 men and 1742 women with serum TSH levels within the reference range (0.50-4.78 µIU/mL) were stratified by quartiles of TSH (Q1-4). MetS was identified according to the criteria of International Diabetes Federation guidelines. Poisson regression models were used to estimate the association between serum TSH and the prevalence of MetS and its components before and after adjustment for potential confounding factors. The reported association was measured using the prevalence ratio (PR) with its respective 95% confidence interval (95% CI).

RESULTS

The prevalence of MetS in euthyroid population across TSH quartiles (Q1-4) was 38.9%, 44.6%, 41.0%, and 47.7%, respectively, in men (P = 0.045), and 47.7%, 46.6%, 46.9%, and 54.6%, respectively, in women (P = 0.032). Compared with the reference group TSH-Q1, the prevalence of MetS was higher among TSH-Q4 group both in men (PR = 1.27; 95% CI: 1.09, 1.48, P = 0.002) and women (PR = 1.21; 95% CI: 1.07, 1.37, P = 0.003) even after adjustment for age, lifestyle factors, serum levels of free triiodothyronine (FT3), and free thyroxine (FT4). Most of the components of MetS were common in higher serum TSH levels within the normal range.

CONCLUSION

The prevalence of MetS and most of its components increased in the higher TSH group in euthyroid Chinese population.

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.

Thyroid replacement therapy, thyroid stimulating hormone concentrations, and long term health outcomes in patients with hypothyroidism: longitudinal study

OBJECTIVE

To explore whether thyroid stimulating hormone (TSH) concentration in patients with a diagnosis of hypothyroidism is associated with increased all cause mortality and a higher risk of cardiovascular disease and fractures.

DESIGN

Retrospective cohort study.

SETTING

The Health Improvement Network (THIN), a database of electronic patient records from UK primary care.

PARTICIPANTS

Adult patients with incident hypothyroidism from 1 January 1995 to 31 December 2017.

EXPOSURE

TSH concentration in patients with hypothyroidism.

MAIN OUTCOME MEASURES

Ischaemic heart disease, heart failure, stroke/transient ischaemic attack, atrial fibrillation, any fractures, fragility fractures, and mortality. Longitudinal TSH measurements from diagnosis to outcomes, study end, or loss to follow-up were collected. An extended Cox proportional hazards model with TSH considered as a time varying covariate was fitted for each outcome.

RESULTS

162 369 patients with hypothyroidism and 863 072 TSH measurements were included in the analysis. Compared with the reference TSH category (2-2.5 mIU/L), risk of ischaemic heart disease and heart failure increased at high TSH concentrations (>10 mIU/L) (hazard ratio 1.18 (95% confidence interval 1.02 to 1.38; P=0.03) and 1.42 (1.21 to 1.67; P<0.001), respectively). A protective effect for heart failure was seen at low TSH concentrations (hazard ratio 0.79 (0.64 to 0.99; P=0.04) for TSH <0.1 mIU/L and 0.76 (0.62 to 0.92; P=0.006) for 0.1-0.4 mIU/L). Increased mortality was observed in both the lowest and highest TSH categories (hazard ratio 1.18 (1.08 to 1.28; P<0.001), 1.29 (1.22 to 1.36; P<0.001), and 2.21 (2.07 to 2.36; P<0.001) for TSH <0.1 mIU/L, 4-10 mIU/L, and >10 mIU/L. An increase in the risk of fragility fractures was observed in patients in the highest TSH category (>10 mIU/L) (hazard ratio 1.15 (1.01 to 1.31; P=0.03)).

CONCLUSIONS

In patients with a diagnosis of hypothyroidism, no evidence was found to suggest a clinically meaningful difference in the pattern of long term health outcomes (all cause mortality, atrial fibrillation, ischaemic heart disease, heart failure, stroke/transient ischaemic attack, fractures) when TSH concentrations were within recommended normal limits. Evidence was found for adverse health outcomes when TSH concentration is outside this range, particularly above the upper reference value.

Relationships of Chronic Kidney Disease and Thyroid Dysfunction in Non-Dialysis Patients: A Pilot Study

<b><i>Context:</i></b> Patients with chronic kidney disease (CKD) usually manifest with disorder of thyroid hormone; however, the correlation is unknown. <b><i>Objective:</i></b> The study was designed to explore the relationships between CKD and thyroid dysfunction. <b><i>Design, Setting, and Participants:</i></b> A total number of 905 non-dialysis participants were collected at Nanjing First Hospital from August 2009 to October 2012 according to the case records system. Patients were grouped via the estimated glomerular filtration rate (eGFR) according to the KDIGO guideline. Levels of thyroid hormone and biomarkers in different CKD groups were compared by ANOVA. Prevalence of different thyroid diseases was calculated by χ² test. <b><i>Results:</i></b> We found that FT3 or T3 became more prevalent with increasing eGFR with the lowest level in CKD5 (<i>p</i> <i>&#x3c;</i> 0.01). No significant differences were found between groups in FT4, T4, or TSH (<i>p</i> &#x3e; 0.05). Frequency of euthyroid sick syndrome (ESS) in CKD groups was high, especially in CKD stage 5 (69.1%, <i>p</i> &#x3c; 0.01). eGFR had positive correlation with T3 and FT3 (<i>r</i> = 0.239, <i>p</i> = 0.0001; <i>r</i> = 0.292, <i>p</i> = 0.0001). ESS had correlations with prealbumin, β2-microglobin, eGFR, and C-reactive protein (<i>r</i> = 0.095, <i>p</i> = 0.004; <i>r</i> = –0.12, <i>p</i> = 0.001; <i>r</i> = 0.091,<i> p</i> = 0.007; <i>r</i> = –0.096, <i>p</i> = 0.008; <i>r</i> = 0.154, <i>p</i> = 0.001). After adjustment for prealbumin, uric acid, HbA1c, age, gender, eGFR, and β2-microglobin, binary regression revealed that hemoglobin, C-reactive protein, and albumin were independent influence factors of ESS (<i>p</i> = 0.016, <i>r</i> = 1.014; <i>p</i> = 0.023, <i>r</i> = 1.007; <i>p</i> = 0.029, <i>r</i> = 0.996). <b><i>Conclusion:</i></b> CKD patients have a high morbidity of ESS, mainly low T3 syndrome. Anemia, inflammation, and malnutrition may contribute to ESS in CKD.

Overt and Subclinical Hypothyroidism in the Elderly: When to Treat?

Hypothyroidism is characterized by increased thyrotropin (TSH) levels and reduced free thyroid hormone fractions while, subclinical hypothyroidism (sHT) by elevated serum TSH in the face of normal thyroid hormones. The high frequency of hypothyroidism among the general population in Western Countries made levothyroxine (LT4) one of the 10 most prescribed drugs. However, circulating TSH has been demonstrated to increase with aging, regardless the existence of an actual thyroid disease. Thus, when confronting an increase in circulating TSH levels in the elderly, especially in the oldest old, it is important to carry an appropriate diagnostic path, comprehensive of clinical picture as well as laboratory and imaging techniques. In the current review, we summarize the recommendations for a correct diagnostic workup and therapeutic approach to older people with elevated TSH value, with special attention to the presence of frailty, comorbidities, and poly-therapy. The treatment of choice for hypothyroid patients is hormone replacement with LT₄ but, it is important to consider multiple factors before commencing the therapy, from the age dependent TSH increase to the presence of an actual thyroid disease and comorbidities. When treatment is necessary, a tailored therapy should be chosen, considering poly-pharmacy and frailty. A careful follow-up and treatment re-assessment should be always considered to avoid the risk of over-treatment. It is important to stress the need of educating the patient for a correct administration of LT₄, particularly when poly-therapy is in place, and the importance of a tailored therapeutic approach and follow-up, to avoid overtreatment.

Hypothyroidism: Cardiovascular Endpoints of Thyroid Hormone Replacement

Thyroid dysfunction, either thyrotoxicosis or hypothyroidism, represents an important cardiovascular risk factor. Heart disease is the leading cause of death for men and women in the United States. Cardiovascular disease is multifactorial and many efforts have been made to assess precipitants for optimal guideline-based, primary, and secondary prevention. Thyroid hormone receptors are present in the myocardium and endothelium, and small alterations in its levels could have significant effects in cardiac function. Specifically, overt hypothyroidism is associated with an increased risk for atherosclerotic cardiovascular disease due to metabolic and hemodynamic effects. Several concomitant factors like impaired lipid profile, low-grade chronic inflammatory state, increased oxidative stress and increased insulin resistance enforce this relationship. The last decade has seen a renewed interest on the impact of subclinical hypothyroidism on the cardiovascular system and whether or not it should be treated. The aim of this review is to provide current evidence of the effect of thyroid hormone replacement, either with levothyroxine mono-therapy or in combination with liothyronine, on specific cardiovascular parameters.

Evaluation of renal function in subclinical hypothyroidism

INTRODUCTION

Patients with subclinical hypothyroidism (SCH) have a few or no symptoms or signs of thyroid dysfunction and thus by its very nature, SCH is a laboratory diagnosis. Serum creatinine is elevated and glomerular filtration rate (GFR) values are reversibly reduced in overt hypothyroid patients. We hypothesize that SCH also may be associated with low GFR.

AIMS AND OBJECTIVES

The objective of this study was (1) to know the effect of SCH on kidney function, (2) to find the correlation between the renal function parameter creatinine, estimated GFR (eGFR), and thyroid-stimulating hormone (TSH), and (3) to know if creatinine values can be predicted by TSH values in SCH cases.

MATERIALS AND METHODS

This is a hospital-based cross-sectional study for 1 year. A total of 608 subjects of either sex were included in the study and were divided into 3 groups: (1) SCH, (2) overt hypothyroidism (OHT), and (3) euthyroidism (ET). TSH, free triiodothyronine, free thyroxine, and serum creatinine were estimated and eGFR was calculated using modification of diet in renal disease study equation and the chronic kidney disease epidemiology collaboration equations.

RESULTS

Serum creatinine levels were higher and eGFR was lower significantly in the subclinical hypothyroid group when compared to the control ET group (P < 0.001). The overtly hypothyroid group had significantly higher levels of serum creatinine and lower eGFR when compared to both the groups (P < 0.001). Significant correlation between TSH, creatinine, and eGFR was found in OHT group only. Linear regression analysis showed the regression in creatinine upon TSH is attributable to 44.5% among OHT group, 48.2% in SCH group.

CONCLUSION

It can be concluded that the SCH group behaves biochemically similar to OHT group and changes in serum creatinine reflect tissue hypothyroidism in SCH cases.

Maternal Thyroid Antibodies Associates With Cardiometabolic Risk Factors in Children at the Age of 16

CONTEXT AND OBJECTIVE

The objective of this study was to determine the effects of maternal thyroid dysfunction or antibodies during pregnancy on the cardiometabolic risk factors in children.

DESIGN, SETTING, AND PARTICIPANTS

This prospective population-based cohort study, Northern Finland Birth Cohort 1986, included all pregnancies within a year in the area. Maternal serum samples were collected before the 20th week of gestation and analyzed for thyrotropin, free T4, thyroid-peroxidase antibodies (TPO-Abs), and thyroglobulin antibodies (Tg-Abs). Cardiometabolic risk factors in children at the age of 16 years were evaluated via blood sampling and clinical examination. Data were available for 3229 to 4176 mother-child pairs.

MAIN OUTCOME MEASURES

Waist circumference, blood pressure, lipids and lipoproteins, and insulin resistance were measured. Odds ratios (ORs) with 95% confidence intervals (CIs) of cardiometabolic risk factors in children with and without mothers with thyroid dysfunction or antibodies were calculated with logistic regression and adjusted for covariates.

RESULTS

Children of TPO-Ab-positive mothers had higher odds of metabolic syndrome (OR, 2.57; 95%, CI 1.26 to 5.25) and waist circumference indicative of metabolic syndrome (OR, 1.69; 95% CI, 1.14 to 2.50). They were also more likely to be overweight or obese (OR, 1.56; 95% CI, 1.04 to 2.34). Maternal thyroid dysfunction or Tg-Ab positivity did not associate with cardiometabolic risk factors in children.

CONCLUSION

Metabolic syndrome, greater waist circumference, and higher body mass index were more prevalent in children of TPO-Ab-positive mothers, indicating an adverse cardiovascular health profile.

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.

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.

Thyroid Hormone Profile in Patients With Acute Coronary Syndrome

Background:

Thyroid hormone has the a major role in the cardiovascular system function and cardiac a As well as to maintain the cardiovascular homeostasis A slightly change ind thyroid status actually affects cardiovascular mortality hemodynamic. The background of this study was to define the prevalence of thyroid dysfunction in acute coronary syndrome (ACS).

Objectives:

The primary objective was to define the prevalence of thyroid dysfunction in acute coronary syndrome, including Non-ST Segment Elevation Myocardial Infarction (NSTEMI), ST-segment Elevation Myocardial Infarction (STEMI), and unstable angina groups. The secondary objective was to determine any associations of thyroids function tests with cardiac catheterization and mortality.

Patients and Methods:

In a prospective, observational, and cross section study, we enrolled 400 patients admitted at the coronary care unit of King Abdulaziz University Hospital in Jeddah, Saudi Arabia. Venous blood samples were collected from patients for the evaluation of thyroid function (thyroids stimulating hormones, free triiodothyronine, and free thyroxin).

Results:

Excluding those taking thyroid hormone preparations, 76.7% of patients admitted with acute coronary heart disease (ST-segment elevation myocardial infarction and Non-ST segment elevation myocardial infarction), and unstable angina had euthyroidism. Thyroid dysfunction was reported in 23.3% of patients with coronary heart disease. Overall hypothyroidism prevalence was 7.8%, while subclinical hyperthyroidism in our study was 2.7%. Overt hyperthyroidism and subclinical hyperthyroidism was reported 2.0% and 0.5%, respectively. Euthyroid sick syndrome was noticed in 41 (10.2%) of critically ill patients. The mortality rate was 9.8%; all death patients had low triiodothyronine (T3) syndrome and were associated with statistically significant low free triiodothyronine (FT3) (P > 0.001).

Conclusions:

No significant variance was observed among patients underwent for cardiac catheterization, STEMI, NSTEMI, unstable angina, and atrial fibrillation with respect to FT4, FT3, and TSH levels during coronary care unit hospitalization based on their profile data.

Effect of iodine restriction on thyroid function in subclinical hypothyroid patients in an iodine-replete area: a long period observation in a large-scale cohort

BACKGROUND

Excessive iodine intake is related to a higher prevalence of hypothyroidism, including subclinical hypothyroidism (SCH), in iodine-replete areas. This study aimed to evaluate the effect of iodine restriction on thyroid function in SCH patients in an iodine-replete area and analyze the relationship between serum thyrotropin (TSH) levels and iodine intake.

METHODS

The study consisted of 146 consecutive patients who were diagnosed with SCH at the Samsung Medical Center between 2010 and 2012. Urinary iodine concentration (UIC) was measured in 82 patients. Of these, 20 patients with UIC < 300 μg/L were excluded, and 62 patients with UIC ≥ 300 μg/L were educated about the restriction of iodine-rich foods. Following the first follow-up visit, these patients were divided into two groups based on the UIC level: group A (well-controlled iodine intake, UIC < 300 μg/L, n = 40), and group B (poorly controlled iodine intake, UIC ≥ 300 μg/L, n = 22). The remaining 64 patients did not restrict iodine rich foods (group C). The 82 patients with measured UICs were reevaluated every 3-6 months, and the median follow-up was 13 months (range 3-32 months). Thyroid function and UIC were measured at each visit. The correlation between serum TSH level and UIC was determined for the 82 patients in whom UIC was measured.

RESULTS

Following 3-6 months of iodine restriction, the serum TSH levels significantly decreased in group A (from 9.0 mU/L to 4.7 mU/L; p < 0.01). In addition, the serum free thyroxine (T4) levels in group A significantly increased (from 1.11 ± 0.23 ng/dL to 1.18 ± 0.17 ng/dL; p < 0.05). However, there were no significant changes in serum TSH or free T4 levels in groups B and C. Serum TSH levels significantly correlated with UIC (r = 0.33, p < 0.01).

CONCLUSION

Iodine restriction may normalize or, at the very least, decrease serum TSH levels in SCH patients, and serum TSH levels are strongly correlated with UIC. Therefore, restriction of iodine intake could be a primary treatment option in SCH patients in an iodine-replete area.

Thyroid hormone signaling and homeostasis during aging

Studies in humans and in animal models show negative correlations between thyroid hormone (TH) levels and longevity. TH signaling is implicated in maintaining and integrating metabolic homeostasis at multiple levels, notably centrally in the hypothalamus but also in peripheral tissues. The question is thus raised of how TH signaling is modulated during aging in different tissues. Classically, TH actions on mitochondria and heat production are obvious candidates to link negative effects of TH to aging. Mitochondrial effects of excess TH include reactive oxygen species and DNA damage, 2 factors often considered as aging accelerators. Inversely, caloric restriction, which can retard aging from nematodes to primates, causes a rapid reduction of circulating TH, reducing metabolism in birds and mammals. However, many other factors could link TH to aging, and it is these potentially subtler and less explored areas that are highlighted here. For example, effects of TH on membrane composition, inflammatory responses, stem cell renewal and synchronization of physiological responses to light could each contribute to TH regulation of maintenance of homeostasis during aging. We propose the hypothesis that constraints on TH signaling at certain life stages, notably during maturity, are advantageous for optimal aging.

Subclinical hypothyroidism in grown-up congenital heart disease patients

Subclinical hypothyroidism usually is asymptomatic, but it can be associated with various adverse cardiologic outcomes. With the objective of gaining insight into the role of thyroid-stimulating hormone (TSH) in congenital heart abnormalities, this study measured serum TSH concentrations in different subtypes of grown-up congenital heart disease (GUCHD) patients. Serum TSH (reference range, 0.34-5.6 mIU/L), creatinine, cholesterol, C-reactive protein (CRP), N-terminal proB-type natriuretic peptide (NT-pro-BNP), and 24-h proteinuria were measured in 249 GUCHD patients. Of 24 GUCHD patients (9.6 %) with a TSH level higher than 5.6 mUI/L, nine were cyanotic (37.5 %) and seven (29.1 %) had Down syndrome. The GUCHD patients with serum TSH exceeding 5.6 mIU/L had a significantly higher level of serum NT-pro-BNP (195.1 [0.28; 5,280.3] vs 57.6 [0.00; 929.8]; p = 0.001) and CRP (0.30 [0.06; 1.87] vs 0.16 [0.00; 1.40]; p = 0.011] than those with a TSH level of 5.6 mIU/L or lower. No significant differences were found in serum creatinine, lipids, or 24-h proteinuria between the two groups. The T4 concentrations in the GUCHD patients with TSH exceeding 5.6 mIU/L were within the normal range (0.89 ± 0.23 ng/dL). In the multivariate analysis, cyanosis (odds ratio [OR], 6,399; 95 % confidence interval [CI] 2,296-17,830; p < 0.001), Down syndrome (OR, 6,208; 95 % CI, 1,963-19,636; p = 0.002), and NT-pro-BNP concentrations (OR, 1,001; 95 % CI, 1,000-1,002; p < 0.026) proved to be risk factors for TSH levels higher than 5.6 mIU/L. Because subclinical hypothyroidism entails a cardiovascular risk, the authors postulate that TSH screening should be included in the routine follow-up evaluation of GUCHD patients with cyanosis or Down syndrome.