Dose–response relationship between thyroid stimulating hormone and hypertension risk in euthyroid individuals

Impaired sensitivity to thyroid hormones is associated with different grades of hypertension: A multicenter cross-sectional study

BACKGROUND AND AIM

Accumulating evidence suggests a potential link between thyroid function with hypertension. However, the research results are limited, and there is no research to explore the relationship between central and peripheral thyroid hormones (THs) sensitivity and different grades of hypertension in patients with coronary heart disease (CHD). This study aims to prove the complex interaction between thyroid system and blood pressure, and provides new ideas for the assessment of hypertension in patients with CHD.

METHODS AND RESULTS

Calculate parameters representing central and peripheral sensitivity to THs. Logistic regression analysis was used to analyze the relationship between central and peripheral THs sensitivity of CHD patients and different grades of hypertension, especially in different ages, sexes, blood glucose levels, smoking, and drinking statuses. Among the 34,310 participants, 19,610 (57.16 %) were diagnosed with hypertension. The risk of hypertension and TSHI (OR: 0.88; 95 % CI: 0.87-0.90; P < 0.001), TT4RI (OR: 0.998; 95 % CI: 0.998-0.999; P < 0.001), TFQI (OR: 0.63; 95 % CI: 0.60-0.67; P < 0.001), PTFQI (OR: 0.63; 95 % CI: 0.59-0.67; P < 0.001) was negatively associated. The risk of hypertension was positively associated with FT3/FT4 (OR: 1.20; 95 % CI: 1.17-1.22; P < 0.001). After stratified analysis, these associations remained significant at different ages, sexes, blood glucose levels, grades of hypertension, smoking, and drinking statuses (P < 0.001).

CONCLUSIONS

This study shows that the decrease in central THs sensitivity index and the increase in peripheral THs sensitivity index are associated with a higher risk of hypertension in CHD patients.

Associations of TSH, free T3, free T4, and conversion ratio with incident hypertension: results from the prospective Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

Objective

To evaluate the association of TSH, free T3 (FT3), free T4 (FT4), and conversion (FT3:FT4) ratio values with incident hypertension.

Materials and methods

The study included data from participants of the ELSA-Brasil study without baseline hypertension. Serum TSH, FT4 and FT3 levels, and FT3:FT4 ratio values were assessed at baseline, and incident hypertension (defined by blood pressure levels ≥ 140/90 mmHg) was estimated over a median of 8.2 years of follow-up. The risk of incident hypertension was evaluated considering a 1-unit increase in TSH, FT4, FT3, and conversion ratio values and after dividing these variables into quintiles for further analysis using Poisson regression with robust variance. The results are presented as relative risks (RR) and 95% confidence intervals (CIs) before and after adjustment for multiple variables.

Results

The primary analysis incorporated data from 5,915 euthyroid individuals, and the secondary analysis combined data from all euthyroid individuals, 587 individuals with subclinical hypothyroidism, and 31 individuals with subclinical hyperthyroidism. The rate of incident hypertension was 28% (95% CI: 27%-29.3%). The FT4 levels in the first quintile (0.18-1.06 ng/dL) were significantly associated with incident hypertension (RR: 1.03, 95% CI: 1.01-1.06) at follow-up. The association between FT4 levels in the first quintile and incident hypertension was also observed in the analysis of combined data from euthyroid individuals and participants with subclinical thyroid dysfunction (RR: 1.04, 95% CI: 1.01-1.07). The associations were predominantly observed with systolic blood pressure levels in euthyroid individuals. However, in the combined analysis incorporating euthyroid participants and individuals with subclinical thyroid dysfunction, the associations were more pronounced with diastolic blood pressure levels.

Conclusion

Low FT4 levels may be a mild risk factor for incident hypertension in euthyroid individuals and persons with subclinical thyroid dysfunction.

The impact of serum uric acid on psoriasis: NHANES 2005-2014 and Mendelian randomization

Background

Psoriasis is a chronic systemic inflammatory disease, and hyperuricemia is a common comorbidity in patients with psoriasis. However, the exact relationship between uric acid levels and psoriasis remains unclear. This study aimed to explore the association between uric acid levels and psoriasis.

Methods

Observational study participant data (≥16 years, n = 23,489) from NHANES 2003-2014. We conducted analyses using a weighted multiple logistic regression model. Genetic data sets for uric acid levels and psoriasis were obtained from the IEU database. We selected genetically independent loci closely associated with serum uric acid levels as instrumental variables and performed Mendelian randomization analyses using five complementary methods: inverse variance weighting (IVW), MR-Egger, weighted median, simple mode, and weighted mode.

Results

After adjusting for other covariates, the results revealed no significant association between serum uric acid levels and psoriasis (b = 0.999, 95% CI: 0.998, 1.001, p = 0.275). Subgroup analyses stratified by gender and ethnicity showed no significant association between sUA and psoriasis in any of the subgroups. Furthermore, the MR analysis involved the selection of 227 SNPs that were associated with both sUA and psoriasis. IVW results demonstrated no causal relationship between sUA and psoriasis (OR = 0.282, 95% CI: -0.094-0.657, p = 0.142).

Conclusion

Our study suggests that uric acid levels are not significantly causally related to psoriasis. This finding provides valuable insights for the treatment and prevention of psoriasis, indicating that merely reducing uric acid levels may not be an effective strategy to reduce the risk of psoriasis onset.

Thyroid-related Hormones and Hypertension Incidence in Middle-Aged and Older Hispanic/Latino Adults: The HCHS/SOL Study

Background

Thyroid-related hormones act to regulate metabolic pathways and blood pressure (BP). However, the relationship of TSH and peripheral thyroid hormones and the role of the hypothalamic-pituitary-thyroid axis on hypertension development is not fully understood. We assessed sex-specific associations of thyroid-related hormones with BP and hypertension in Hispanic/Latino adults followed for 6 years.

Methods

We studied 1789 adults, ages 45 to 74, free of diabetes at baseline from a subcohort of the Hispanic Community Health Study/Study of Latinos. We assessed TSH, free T4 (FT4), T3, and various indicators of thyroid axis. Using multivariable linear and Poisson regression adjusted for survey design and confounding variables, we estimated a priori sex-specific associations of thyroid-related hormones with changes in BP and hypertension development.

Results

In men and women, TSH and TSH/FT4 ratios were associated with changes in diastolic BP and T3 with changes in pulse pressure and the development of hypertension from prehypertension. In men, a 1-SD increase in TSH [incident rate ratio (IRR) = 1.42; 95% confidence interval (CI): 1.15, 1.75] and TSH/FT4 ratio (IRR = 1.20; 95% CI: 1.07, 1.35) were positively associated with the development of hypertension from prehypertension while the TSH/FT4 ratio (IRR = 0.85; 95% CI: .72, 1.00) was protective in women. We observed sex-specific differences in associations of the T3/FT4 ratio and indices of pituitary sensitivity to thyroid hormones with changes in pulse pressure and hypertension development.

Conclusion

Thyroid-related hormones are associated with sex-specific changes in BP and hypertension among Hispanic/Latino adults consistent with selected studies conducted in other populations. Mechanisms underlying associations of pituitary sensitivity to thyroid hormones with BP and hypertension development warrant further study.

Thyroid Hormone Resistance Syndrome: From Molecular Mechanisms to Its Potential Contribution to Hypertension

Thyroid hormone resistance (THR) is a rare inherited disorder that affects approximately one in every 40,000 live births. This condition arises from a mutation in the thyroid hormone receptor β, leading to reduced responsiveness of target tissues. It can result in a combination of hypothyroidism and hyperthyroidism symptoms in different tissues. The thyroid hormone is crucial for controlling blood pressure, and even small changes in its levels can have an effect on vascular resistance, cardiac performance, and heart rhythm. Both hypo- and hyperthyroidism have been associated with elevated blood pressure, underscoring the significant link between thyroid hormone sensitivity and vascular function. Considering thyroid hormone sensitivity is essential in clinical practice, particularly when managing patients with hypertension, to ensure personalized and effective treatment approaches. Monitoring thyroid function is essential during the diagnosis of hypertension, as thyroid dysfunction can often be corrected to normalize blood pressure. It's crucial to distinguish between essential hypertension and hypertension associated with a thyroid abnormality in THR. The mechanisms behind the development of hypertension in THR include reduced nitric oxide production, dysregulation of the renin-angiotensin-aldosterone system, impaired endothelial function, and mutations in the deiodinases. Physicians should understand the underlying mechanisms of THR and identify new therapeutic targets for hypertension in THR.

Effect of coffee consumption on thyroid function: NHANES 2007-2012 and Mendelian randomization

Background

Coffee is one of the most consumed beverages worldwide, but the effects on the thyroid are unknown. This study aims to examine the association between coffee and thyroid function.

Methods

Participant data (≥ 20 years, n = 6578) for the observational study were obtained from NHANES 2007-2012. Analysis was performed using weighted linear regression models and multiple logistic regression models. Genetic datasets for Hyperthyroidism and Hypothyroidism were obtained from the IEU database and contained 462,933 European samples. Mendelian randomization (MR) was used for the analysis, inverse variance weighting (IVW) was the main method of analysis.

Results

In the model adjusted for other covariates, participants who drank 2-4 cups of coffee per day had significantly lower TSH concentrations compared to non-coffee drinkers (b=-0.23, 95% CI: -0.30, -0.16), but no statistically significant changes in TT4, FT4, TT3 and FT3. In addition, participants who drank <2 cups of coffee per day showed a low risk of developing subclinical hypothyroidism. (OR=0.60, 95% CI: 0.41, 0.88) Observational studies and MR studies have demonstrated both that coffee consumption has no effect on the risk of hyperthyroidism and hypothyroidism.

Conclusions

Our study showed that drinking <2 cups of coffee per day reduced the risk of subclinical hypothyroidism and drinking 2-4 cups of coffee reduced serum TSH concentrations. In addition, coffee consumption was not associated with the risk of hyperthyroidism and hypothyroidism.

Age-related variation in thyroid function - a narrative review highlighting important implications for research and clinical practice

BACKGROUND

Thyroid hormones are key determinants of health and well-being. Normal thyroid function is defined according to the standard 95% confidence interval of the disease-free population. Such standard laboratory reference intervals are widely applied in research and clinical practice, irrespective of age. However, thyroid hormones vary with age and current reference intervals may not be appropriate across all age groups. In this review, we summarize the recent literature on age-related variation in thyroid function and discuss important implications of such variation for research and clinical practice.

MAIN TEXT

There is now substantial evidence that normal thyroid status changes with age throughout the course of life. Thyroid stimulating hormone (TSH) concentrations are higher at the extremes of life and show a U-shaped longitudinal trend in iodine sufficient Caucasian populations. Free triiodothyronine (FT3) levels fall with age and appear to play a role in pubertal development, during which it shows a strong relationship with fat mass. Furthermore, the aging process exerts differential effects on the health consequences of thyroid hormone variations. Older individuals with declining thyroid function appear to have survival advantages compared to individuals with normal or high-normal thyroid function. In contrast younger or middle-aged individuals with low-normal thyroid function suffer an increased risk of adverse cardiovascular and metabolic outcomes while those with high-normal function have adverse bone outcomes including osteoporosis and fractures.

CONCLUSION

Thyroid hormone reference intervals have differential effects across age groups. Current reference ranges could potentially lead to inappropriate treatment in older individuals but on the other hand could result in missed opportunities for risk factor modification in the younger and middle-aged groups. Further studies are now needed to determine the validity of age-appropriate reference intervals and to understand the impact of thyroid hormone variations in younger individuals.

Assessment of causal direction between thyroid function and cardiometabolic health: a Mendelian randomization study

BACKGROUND

Growing evidence have demonstrated that thyroid hormones have been involved in the processes of cardiovascular metabolism. However, the causal relationship of thyroid function and cardiometabolic health remains partly unknown.

METHODS

The Mendelian randomization (MR) was used to test genetic, potentially causal relationships between instrumental variables and cardiometabolic traits. Genetic variants of free thyroxine (FT4) and thyrotropin (TSH) levels within the reference range were used as instrumental variables. Data for genetic associations with cardiometabolic diseases were acquired from the genome-wide association studies of the FinnGen, CARDIoGRAM and CARDIoGRAMplusC4D, CHARGE, and MEGASTROKE. This study was conducted using summary statistic data from large, previously described cohorts. Association between thyroid function and essential hypertension (EHTN), secondary hypertension (SHTN), hyperlipidemia (HPL), type 2 diabetes mellitus (T2DM), ischemic heart disease (IHD), myocardial infarction (MI), heart failure (HF), pulmonary heart disease (PHD), stroke, and non-rheumatic valve disease (NRVD) were examined.

RESULTS

Genetically predicted FT4 levels were associated with SHTN (odds ratio = 0.48; 95% CI = 0.04−0.82,P = 0.027), HPL (odds ratio = 0.67; 95% CI = 0.18−0.88,P = 0.023), T2DM (odds ratio = 0.80; 95% CI = 0.42−0.86,P = 0.005), IHD (odds ratio = 0.85; 95% CI = 0.49−0.98,P = 0.039), NRVD (odds ratio = 0.75; 95% CI = 0.27−0.97,P = 0.039). Additionally, genetically predicted TSH levels were associated with HF (odds ratio = 0.82; 95% CI = 0.68−0.99,P = 0.042), PHD (odds ratio = 0.75; 95% CI = 0.32−0.82,P = 0.006), stroke (odds ratio = 0.95; 95% CI = 0.81−0.97,P = 0.007). However, genetically predicted thyroid function traits were not associated with EHTN and MI.

CONCLUSIONS

Our study suggests FT4 and TSH are associated with cardiometabolic diseases, underscoring the importance of the pituitary-thyroid-cardiac axis in cardiometabolic health susceptibility.

Metabolic risk factors among prediabetic individuals and the trajectory toward the diabetes incidence

BACKGROUND

This study investigates the trajectory of the risk factors of prediabetes progression to overt diabetes.

METHODS

The study retrospectively investigated 1610 prediabetic individuals. The trajectory of metabolic indicators was investigated using the generalized estimated equation method with autoregressive working correlation structure through a linear model with the identity link function.

RESULTS

During 15 years of follow-up, the trajectories of metabolic risk factors changed from 3 years before diabetes occurrence for fasting plasma glucose (FPG) and 2-hour plasma glucose (2hPG), 6 years for waist circumference (WC), 9 years for high-density lipoprotein cholesterol (HDL-C), and earlier for body mass index, triglyceride (TG), and TG:HDL ratio. It was shown that the differences in the trajectory of WC and HDL were stable after adjustment for other metabolic risk factors. The trajectories of FPG and 2hPG remained stable after considering multiple insulin resistance markers.

CONCLUSIONS

Deterioration of metabolic risk factor status can be a predictor of diabetes many years before its occurrence, but the abrupt change in plasma glucose is evident 3 years before diabetes mellitus onset. It seems that the HDL-C and WC trajectories are two independent predictors for diabetes incidence. It was also found that when the rising trend in plasma glucose starts, preventive strategies to lessen insulin resistance might not be efficient.

Variation in Normal Range Thyroid Function Affects Serum Cholesterol Levels, Blood Pressure, and Type 2 Diabetes Risk: A Mendelian Randomization Study

Background: Observational studies have demonstrated that variation in normal range thyroid function is associated with major cardiovascular risk factors, including dyslipidemia, hypertension, type 2 diabetes (T2D), and obesity. As observational studies are prone to residual confounding, reverse causality, and selection bias, we used a Mendelian randomization (MR) approach to investigate whether these associations are causal or not. Methods: Two-sample MR analysis using data from the largest available genome-wide association studies on normal range thyrotropin (TSH) and free thyroxine (fT4) levels, serum lipid levels, blood pressure measurements, T2D, and obesity traits (body mass index [BMI] and waist/hip ratio). Results: A one standard deviation (SD) increase in genetically predicted TSH levels was associated with a 0.037 SD increase in total cholesterol levels (p = 3.0 × 10-4). After excluding pleiotropic instruments, we also observed significant associations between TSH levels and low-density lipoprotein levels (β = 0.026 SD, p = 1.9 × 10-3), pulse pressure (β = -0.477 mmHg, p = 7.5 × 10-10), and T2D risk (odds ratio = 0.95, p = 2.5 × 10-3). While we found no evidence of causal associations between TSH or fT4 levels and obesity traits, we found that a one SD increase in genetically predicted BMI was associated with a 0.075 SD decrease in fT4 levels (p = 3.6 × 10-4). Conclusions: Variation in normal range thyroid function affects serum cholesterol levels, blood pressure, and T2D risk.

The association between longitudinal trends of thyroid hormones levels and incident hypertension in a euthyroid population

Thyroid hormones, including free triiodothyronine (FT3), free thyroxine (FT4), have well-recognized effects on the cardiovascular system. However, the evidence is lacking regarding the relationship between repeated FT3, FT4, and thyroid-stimulating hormone (TSH) measurements and incident hypertension. The aim of this cohort study was to examine how longitudinal trends of serum FT3, FT4, and TSH levels are related to the development of hypertension in a euthyroid population. A prospective study (n = 5926) was performed in Tianjin, China. Participants without a history of hypertension were followed up for ~4 years (median: 3 years). Hypertension was defined according to the criteria of JNC7. FT3, FT4, and TSH were determined by chemiluminescence immunoassay methods. FT3, FT4, TSH, and blood pressure were assessed yearly during follow-up. Adjusted Cox proportional hazards regression models were used to assess the relationships between baseline, means, and annual changes in FT3, FT4, TSH, and hypertension. The incidence rate of hypertension per 1000 person-years was 73. Compared with the lowest quartile, the multivariable-adjusted hazards ratios (95% confidence interval) for hypertension in the highest quartiles of changes in FT3, FT4, and TSH were 1.51 (1.23-1.84), 2.04 (1.67-2.48), and 1.20 (0.99-1.45), respectively. Similar relationships were observed between the means of FT3, FT4, TSH, and hypertension. However, we found no correlations between baseline FT3, FT4, TSH, and incident hypertension. The present study is the first to demonstrate that the annual changes and means, but not baseline FT3 and FT4 values are independently related to the risk of incident hypertension in the euthyroid general population.

Diagnosis and Management of Endocrine Hypertension in Children and Adolescents

Hypertension in childhood and adolescence has increased in prevalence. Interest in the disease was raised after the 2017 clinical practice guidelines of the American Academy of Paediatrics on the definition and classification of paediatric hypertension. Among the secondary causes of paediatric hypertension, endocrine causes are relatively rare but important due to their unique treatment options. Excess of catecholamine, glucocorticoids and mineralocorticoids, congenital adrenal hyperplasia, hyperaldosteronism, hyperthyroidism and other rare syndromes with specific genetic defects are endocrine disorders leading to paediatric and adolescent hypertension. Adipose tissue is currently considered the major endocrine gland. Obesity-related hypertension constitutes a distinct clinical entity leading to an endocrine disorder. The dramatic increase in the rates of obesity during childhood has resulted in a rise in obesity-related hypertension among children, leading to increased cardiovascular risk and associated increased morbidity and mortality. This review presents an overview of pathophysiology and diagnosis of hypertension resulting from hormonal excess, as well as obesity-related hypertension during childhood and adolescence, with a special focus on management.

Association between serum TSH levels and metabolic components in euthyroid subjects: a nationwide population-based study

BACKGROUND

Whether a relationship exists between various metabolic factors and thyroid-stimulating hormone (TSH) levels in euthyroid persons remains unknown. This study aims to explore the relationship between TSH levels and metabolic factors in euthyroid individuals.

METHODS

A total of 2,663 subjects were enrolled from a nationwide population-based cross-sectional survey of iodine nutrition, thyroid disease and diabetes in China (2014-2017). Euthyroid individuals were divided into four groups according to quartiles of TSH levels: group A (n=305, 0.3-1.3 mIU/L), group B (n=829, 1.3-2.2 mIU/L), group C (n=673, 2.2-3.2 mIU/L) and group D (n=349, 3.2-4.2 mIU/L). Anthropometric parameters, biochemical indicators and TSH levels were determined.

RESULTS

A total of 2,156 euthyroid subjects with serum TSH levels within the normal range accounted for 86.8% of the sample. The systolic blood pressure (SBP) in group D was significantly higher than that in the other three groups. Group C displayed significantly lower thyroid peroxidase antibody (TPOAb) levels than the other three groups. Group C also had lower anti-thyroglobulin antibody (TgAb) levels than groups A and D, whereas the TgAb levels in group B were only lower than those in group A. Spearman's or Pearson's linear regression analysis showed that SBP (r=0.054; P=0.013) was positively correlated with TSH, but cholesterol (TC) (r=-0.043, P=0.047) was negatively correlated with TSH. Multiple stepwise regression analysis revealed that SBP, the urinary iodine concentration (UIC), waist circumference (WC), body mass index (BMI), TC, triglycerides (TGs) and low-density lipoprotein cholesterol (LDL-C) were independent predictors of serum TSH levels.

CONCLUSION

This large population-based study demonstrates a significant interaction between metabolic factors and TSH levels. An adverse weight status, high blood pressure levels, blood lipid metabolism disorder and excessive iodine intake may be early manifestations of thyroid disease in euthyroid subjects.

Gender-Specific Differences on the Association of Hypertension with Subclinical Thyroid Dysfunction

OBJECTIVE

Both hypertension and subclinical thyroid dysfunction (STD) have high prevalence and clinical importance, but their relationship is still a matter of debate. We aimed to explore gender-specific difference on the association between hypertension and STD in Chinese.

METHODS

We recruited 13,380 ostensible healthy participants (8,237 men and 5,143 women). The associations between hypertension and STD were analyzed on a gender-based setting after dividing STD into subclinical hypothyroidism, subclinical hyperthyroidism and further subgrouped euthyroidism. Crude and adjusted odds ratios of STD for hypertension were analyzed by binary logistic regression.

RESULTS

An increasing trend of hypertension prevalence was found along with aging in both genders. Yet, higher male hypertension prevalence was found until 65 years, and then it intersected with female hypertension prevalence. Women had significantly higher propensity for STD than men. Yet, in elderly participants, this gender-specific difference became less obvious. We displayed detrimental effects for subclinical hypothyroidism in both genders after multiple-covariate adjustments, yet no such effects were shown for subclinical hyperthyroidism. Moreover, females with subclinical hypothyroidism were more likely to be associated with hypertension than males, and the corresponding odds ratios were 1.619 (P < 0.01) and 1.557 (P < 0.01) and 1.557 (P < 0.01) and 1.557 (P < 0.01) and 1.557 (P < 0.01) and 1.557 (P < 0.01) and 1.557 (.

CONCLUSION

We demonstrate that hypertension is associated with subclinical hypothyroidism, but not with subclinical hyperthyroidism. Moreover, females with subclinical hypothyroidism are more likely to be associated with hypertension than males.

Effect of Levothyroxine on Blood Pressure in Patients With Subclinical Hypothyroidism: A Systematic Review and Meta-Analysis

Background: Patients with subclinical hypothyroidism (SCH) have elevated blood pressure, but the effect of levothyroxine (LT4) therapy on blood pressure among those patients is still unclear. This study aimed to assess whether LT4 therapy could reduce blood pressure in SCH patients through a systematic review and meta-analysis. Methods: PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science were searched. Randomized controlled trials (RCTs) assessing the effect of LT4 therapy on blood pressure or prospective follow-up studies comparing the blood pressure level before and after LT4 treatment were included, and the mean difference of systolic blood pressure (SBP) or diastolic blood pressure (DBP) was pooled using random-effect meta-analysis. Results: Twenty-nine studies including 10 RCTs and 19 prospective follow-up studies were eligible for the analysis. Meta-analysis of 10 RCTs suggested that LT4 therapy could significantly reduce SBP in SCH patients by 2.48 mmHg (95% CI -4.63 to -0.33, P = 0.024). No heterogeneity was observed among these 10 RCTs (I² = 0%). Meta-analysis of the 19 prospective follow-up studies found that LT4 therapy significantly decreased SBP and DBP by 4.80 mmHg (95%CI -6.50 to -3.09, P < 0.001) and 2.74 mmHg (95%CI -4.06 to -1.43, P < 0.001), respectively. Conclusion: The findings suggest that LT4 replacement therapy can reduce blood pressure in SCH patients, which needs to be validated in more clinical trials with larger samples.