Hypertension and hypothyroidism: results from an ambulatory blood pressure monitoring study

A Cross-Sectional Study on the Prevalence of Subclinical Hypothyroidism in Metabolic Syndrome Patients at a Tertiary Care Hospital

BACKGROUND AND OBJECTIVE

Metabolic syndrome (MetS) is defined as a "constellation" of cardiometabolic risk factors, characterized by hypertension, atherogenic dyslipidemia, hyperglycemia, prothrombotic and proinflammatory conditions which, jointly, increase the risk of suffering cardiovascular diseases (CVD) and type 2 diabetes mellitus. Thyroid dysfunction is also believed to affect parameters such as high-density lipoprotein (HDL) cholesterol, triglycerides, plasma glucose, and blood pressure, in turn increasing the risk of CVD. Subclinical hypothyroidism (SCH), which independently raises the risk of CVDs and their associated complications, is more frequently detected in patients with MetS compared to the general population. When both conditions coexist, the risk of CVD and its complications is significantly heightened. The objective of the study was to find out the prevalence of SCH in patients with MetS.

METHODS

A prospective cross-sectional study was conducted in the Department of General Medicine, New Civil Hospital, Surat, Gujarat, India. Eighty patients who fulfilled the criteria for MetS by the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III), were taken into the study. A detailed history, anthropometric measurements, blood pressure, fasting blood glucose, lipid profile, and thyroid profile (Free T3, Free T4, and serum thyroid-stimulating hormone (TSH)) were undertaken. The thyroid profile was done by chemiluminescence immunoassay (CLIA) method.

RESULTS

Out of 80 patients with MetS, 48 were female and 32 were male, with the overall mean age of the study population being 46.5±9.5 years. Among them, 23.7% of the population was found to be having thyroid dysfunction. Among the thyroid dysfunction, SCH was highly prevalent (18.8%), 3.8% patients had overt hypothyroidism and 1.3% patients had subclinical hyperthyroidism. There were no overt hyperthyroid patients in our study. HDL (mg/dl) and TSH (mIU/L) were significantly higher in the SCH group as compared to other types of hypothyroidism group (p-value < 0.05).

DISCUSSION

There is a statistically significant prevalence of SCH (18.8%) in MetS patients. It is clear from the study that one-fifth of MetS patients or every fifth patient with MetS had SCH. Thus, looking proactively for SCH in MetS and treating it would prevent conversion to overt hypothyroidism and complications of MetS.

The predictive value of free thyroxine combined with tubular atrophy/interstitial fibrosis for poor prognosis in patients with IgA nephropathy

Background

IgA nephropathy (IgAN), the most common type of glomerulonephritis, has great individual differences in prognosis. Many studies showed the relationship between thyroid hormones and chronic kidney disease. However, the relationship between free thyroxine (FT4), as a thyroid hormone, and IgAN is still unclear. This study aimed to evaluate the impact of FT4 on IgAN prognosis.

Methods

This retrospective study involved 223 patients with biopsy-proven IgAN. The renal composite outcomes were defined as: (1) ESRD, defined as eGFR < 15 ml/(min·1.73 m2) or initiation of renal replacement therapy (hemodialysis, peritoneal dialysis, renal transplantation); (2) serum creatinine doubled from baseline; (3) eGFR decreased by more than 50% from baseline. The predictive value was determined by the area under the curve (AUC). Kaplan-Meier and Cox proportional hazards analyses assessed renal progression and prognosis.

Results

After 38 (26-54) months of follow-up, 23 patients (10.3%) experienced renal composite outcomes. Kaplan-Meier survival curve analysis showed that the renal survival rate of the IgAN patients with FT4<15.18pmol/L was lower than that with FT4≥15.18pmol/L (P < 0. 001). Multivariate Cox regression model analysis showed that FT4 was a protective factor for poor prognosis of IgAN patients, whether as a continuous variable or a categorical variable (HR 0.68, 95%CI 0.51-0.90, P =0.007; HR 0.04, 95%CI 0.01-0.20, P <0.001). ROC curve analysis showed that FT4 combined with t score had a high predictive value for poor prognosis of IgAN patients (AUC=0.881, P<0.001).

Conclusion

FT4 was a protective factor for IgAN. In addition, FT4 combined with tubular atrophy/interstitial fibrosis had a high predictive value for poor prognosis of IgAN.

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.

Endocrinological disorders in acute kidney injury: an often overlooked field of clinical research

Acute kidney injury (AKI) is a common comorbidity, affecting approximately one in five hospitalized adults. The kidney is the site for the production, metabolism or excretion of most hormones, including the production of erythropoietin (EPO), the active form of vitamin D, renin, thrombopoietin, and the excretion of insulin, catecholamines, gastrin and many other hormones. Therefore, it is reasonable to say that AKI can have a considerable impact on the endocrine system. Although the effects of AKI on various parameters, including cardiovascular parameters, serum electrolytes and acid-base disorders, neuro-humoral mechanisms and neurological outcomes have been extensively studied, the endocrinological consequences of AKI are understudied. Thyroid dysfunction, mainly euthyroid sick syndrome, hypo/hyperglycemia, bone mineral disorders, changes in EPO and atrial natriuretic peptide (ANP) levels are commonly found in AKI. EPO, thyroxine and ANP administration have been evaluated as potential tools to prevent or treat AKI with varying success, while the effects of AKI on some key hormones, including cortisol and insulin, have never been studied. Aim of this narrative review is to illustrate what is known and what is not known about the endocrinological outcomes of AKI. Few clinical trials are ongoing: however, there is a clear need for large-scale randomized controlled trials investigating the endocrinological consequences of AKI.

Association between DIO2 Thr92Ala polymorphism and hypertension in patients with hypothyroidism: Korean Genome and Epidemiology Study

BACKGROUND/AIMS

Recent evidence has identified the significance of type 2 iodothyronine deiodinase (DIO2) in various diseases. However, the role of DIO2 polymorphism in metabolic parameters in patients with hypothyroidism is not fully understood.

METHODS

We assessed the polymorphism of the DIO2 gene and various clinical parameters in 118 patients who were diagnosed with hypothyroidism from the Ansan-Anseong cohort of the Korean Genome and Epidemiology Study. Furthermore, we systematically analyzed Genotype-Tissue Expression (GTEx) data.

RESULTS

A total of 118 participants with hypothyroidism were recruited; 32 (27.1%) were homozygous for the Thr allele, 86 (73.9%) were homozygous for the Ala allele or heterozygous. Patients with hypothyroidism with DIO2 polymorphism without hypertension at baseline had higher incidence of hypertension compared to patients without DIO2 polymorphism. Analysis of the GTEx database revealed that elevation of DIO2 expression is associated with enhancement of genes involved in blood vessel regulation and angiogenesis.

CONCLUSION

Commonly inherited variation in the DIO2 gene is associated with high blood pressure and prevalence of hypertension in patients with hypothyroidism. Our results suggest that genetic variation in the hypothalamic-pituitary-thyroid pathway in influencing susceptibility to hypertension.

Hypothyroidism correlates with dyslipidemia and protein contents in patients with various metabolic disorders

OBJECTIVES

The present study aimed to investigate the status of abnormalities in thyroid-related hormones, lipid profile parameters and total proteins in the sera of patients suffering from various metabolic disorders.

METHODS

To analyze the study parameters, enzyme-linked immunosorbent assays, Bradford assays and standard clinical kits and methods were applied. Data were analyzed through the appropriate statistical tests.

RESULTS

In all subjects except those with hypotension, thyroid-stimulating hormone, total cholesterol and low-density lipoprotein were elevated, whereas triiodothyronine levels were downregulated. Thyroxin was downregulated in subjects with diabetes and symptomatic thyroiditis but upregulated in patients with hypertension. High-density lipoprotein was upregulated in men who were diabetic only, and total protein was downregulated in those with hypotension only. Hypothyroidism in patients with diabetes, symptomatic thyroiditis and hypertension was correlated with dyslipidemia. In subjects with hypertension, it was correlated with total protein.

CONCLUSION

This study revealed a link between hypothyroidism, dyslipidemia and total protein in patients with various metabolic disorders.

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.

Differences in food consumption between patients with Hashimoto's thyroiditis and healthy individuals

Food is considered as important environmental factor that plays a role in development of Hashimoto's thyroiditis (HT). The goal of our study was to identify food groups, assessed by food frequency questionnaire, that differ in consumption frequency between 491 patients with HT and 433 controls. We also analysed association of food groups with the wealth of HT-related clinical traits and symptoms. We found significantly increased consumption of animal fat (OR 1.55, p < 0.0001) and processed meat (OR 1.16, p = 0.0012) in HT cases, whereas controls consumed significantly more frequently red meat (OR 0.80, p < 0.0001), non-alcoholic beverages (OR 0.82, p < 0.0001), whole grains (OR 0.82, p < 0.0001) and plant oil (OR 0.87, p < 0.0001). We also observed association of plant oil consumption with increased triiodothyronine levels in HT patients (β = 0.07, p < 0.0001), and, association of olive oil consumption with decreased systolic blood pressure (β = − 0.16, p = 0.001) in HT patients on levothyroxine (LT4) therapy. Analysis of food consumption between HT patients with and without LT4 therapy suggest that patients do not tend to modify their diet upon HT diagnosis in our population. Our study may be of relevance to nutritionists, nutritional therapists and clinicians involved in developing dietary recommendations for HT patients.

Metformin effect on TSH in subclinical hypothyroidism: randomized, double-blind, placebo-controlled clinical trial

INTRODUCTION

Non-randomized trials suggest that metformin may reduce TSH levels through unknown mechanisms.

OBJECTIVE

To evaluate whether metformin can reduce TSH levels in subjects with subclinical hypothyroidism.

PATIENTS AND METHODS

This is a randomized, double-blind, placebo controlled clinical trial with 3 months duration that enrolled 48 individuals, between 18 and 65 years, with subclinical hypothyroidism. The patients were randomized to the use of metformin 850 mg or placebo twice a day for 3 months. The primary outcome was the absolute decrease in TSH levels. Secondary outcomes were changes in the clinical and laboratory assessment, as well as in blood pressure assessed by ambulatory blood pressure monitoring.

RESULTS

After 3 months, 93.75% of participants completed the follow-up. The post treatment value of TSH in the metformin and placebo groups were 6.48 ± 3.11 and 7.02 ± 3.28 mIU/L, respectively (p = 0.57). Patients who achieved status of euthyroidism in the metformin and placebo groups were 21.7 and 18.2%, respectively (p = 0.76). There was no significant reduction of TSH within the groups [delta for TSH of 0.63 ± 0.56 (p = 0.28) and 0.54 ± 0.60 mIU/L (p = 0.38), in metformin and placebo groups, respectively]. There was a small increase in HDL cholesterol (1.62 ± 0.45 vs. 1.34 ± 0.39 mmol/L, p = 0.03) favoring the metformin group.

CONCLUSION

Since the sample size was small, the study was inconclusive and the results should be considered preliminary data of a study that needs to enroll 1626 patients to show a 0.5 mIU/L difference in TSH between the groups, with 90% power.

Thyroid-stimulating hormone, anti-thyroid antibodies, and pregnancy outcomes

BACKGROUND

Overt thyroid dysfunction has been associated with adverse obstetric outcomes. However, less is known regarding subclinical hypothyroidism or thyroid autoimmunity and their relationship to pregnancy complications.

OBJECTIVE

The purpose of this study was to examine the association between prepregnancy anti-thyroid antibodies and subclinical hypothyroidism and preterm delivery, gestational diabetes mellitus, and preeclampsia.

STUDY DESIGN

We conducted a secondary analysis of a prospective cohort of 18- to 40-year-old women with 1-2 previous pregnancy losses (n=1193) who participated in a multicenter randomized, placebo-controlled trial of low-dose aspirin. Prepregnancy levels of thyroid-stimulating hormone, free thyroxine, thyroglobulin antibody, and thyroid peroxidase antibody were measured. Relative risks and 95% confidence intervals were estimated with the use of generalized linear models with adjustment for age and body mass index.

RESULTS

Among women with an ongoing pregnancy of >20 weeks estimated gestational age, there was no association between prepregnancy thyroid-stimulating hormone level (>2.5 vs ≤2.5 mIU/L) and preterm delivery (adjusted relative risk, 0.77; 95% confidence interval, 0.40-1.47), gestational diabetes mellitus (adjusted relative risk, 1.28; 95% confidence interval, 0.54-3.04), or preeclampsia (adjusted relative risk, 1.20; 95% confidence interval, 0.71-2.04). Similarly, among women with thyroid antibodies, there was no increase in the likelihood of preterm delivery (relative risk, 1.26; 95% confidence interval, 0.65-2.45), gestational diabetes mellitus (relative risk, 1.33; 95% confidence interval, 0.51-3.49), or preeclampsia (relative risk, 1.02; 95% confidence interval, 0.54-1.92), compared with women without these antibodies.

CONCLUSION

Among women with 1-2 previous pregnancy losses, subclinical hypothyroidism and thyroid autoimmunity were not associated with an increased risk of preterm delivery, gestational diabetes mellitus, or preeclampsia. These data support current recommendations that low-risk asymptomatic women should not be screened routinely for thyroid dysfunction or autoimmunity.

Thyroid dysfunction and kidney disease: An update

Thyroid hormones influence renal development, kidney hemodynamics, glomerular filtration rate and sodium and water homeostasis. Hypothyroidism and hyperthyroidism affect renal function by direct renal effects as well as systemic hemodynamic, metabolic and cardiovascular effects. Hypothyroidism has been associated with increased serum creatinine and decreased glomerular filtration rate. The reverse effects have been reported in thyrotoxicosis. Most of renal manifestations of thyroid dysfunction are reversible with treatment. Kidney disease may also cause thyroid dysfunction by several mechanisms. Nephrotic syndrome has been associated to changes in serum thyroid hormone concentrations. Different forms of glomerulonephritis and tubulointerstitial disease may be linked to thyroid derangements. A high prevalence of thyroid hormone alteration has been reported in acute kidney injury. Thyroid dysfunction is highly prevalent in chronic kidney disease patients. Subclinical hypothyroidism and low triiodothyronine syndrome are common features in patients with chronic kidney disease. Patients treated by both hemodialysis and peritoneal dialysis, and renal transplantation recipients, exhibit thyroid hormone alterations and thyroid disease with higher frequency than that found in the general population. Drugs used in the therapy of thyroid disease may lead to renal complications and, similarly, drugs used in kidney disorders may be associated to thyroid alterations. Lastly, low thyroid hormones, especially low triiodothyronine levels, in patients with chronic kidney disease have been related to a higher risk of cardiovascular disease and all-cause mortality. Interpretation of the interactions between thyroid and renal function is a challenge for clinicians involved in the treatment of patients with thyroid and kidney disease.

Masked hypertension in newly diagnosed hypothyroidism: a pilot study

PURPOSE

Masked hypertension (MH) is the association of normal office blood pressure (BP) with high ambulatory or home BP. This condition is associated with increased cardiovascular target organ damage, as true hypertension. Because the relation with hypothyroidism is controversial, we investigated it in a pilot longitudinal and controlled study.

METHODS

We consecutively enrolled 64 newly diagnosed hypothyroid patients, 38 subclinical (s-HYPO), and 26 overt (o-HYPO). The control group consisted of 50 euthyroid subjects seen at outpatient clinics. All participants underwent office and 24-h ambulatory BP measurement.

RESULTS

BP monitoring revealed a higher prevalence of MH both in s-HYPO (26.3 %) and in o-HYPO (15.4 %) than in euthyroid subjects (10 %, p = 0.05); true hypertension also was more frequent in o-HYPO (11.5 %) and s-HYPO (10.5 %) than in controls (8 %, p = 0.03). The odds ratio for hypertension versus normotension confirmed a significantly increased risk of MH in hypothyroid patients versus euthyroid subjects (3.29, 1.08-10.08; p = 0.02). In a subgroup of patients reevaluated after restoration of euthyroidism, an improvement of BP profile was observed, especially in s-HYPO subgroup, with a decreased prevalence of MH (from 25 to 10.7 %) and true hypertension (from 10.7 to 3.4 %).

CONCLUSIONS

Hypothyroidism may be an important predictor of higher BP values, with an increased risk of MH. Because MH is a cardiovascular risk and can be reversed by thyroid hormone replacement, its presence should represent an indication for thyroid hormone replacement therapy also in patients with s-HYPO.

Diminished Quality of Life and Increased Brain Functional Connectivity in Patients with Hypothyroidism After Total Thyroidectomy

BACKGROUND

Acute hypothyroidism induced by thyroid hormone withdrawal (THW) in patients with thyroid cancer after total thyroidectomy can affect mood and quality of life (QoL). While loss or dysregulation of thyroid hormone (TH) has these well-known behavioral consequences, the effects of TH alterations on brain function are not well understood. Resting state functional connectivity (FC) measured by functional magnetic resonance imaging (fMRI) allows non-invasive evaluation of human brain function. This study therefore examined whether THW affects resting state FC and whether changes in FC correlate with the mood or QoL of the patients with THW status.

METHODS

Twenty-one patients who had undergone total thyroidectomy for thyroid cancer were recruited. Resting state fMRI scanning of the brain, thyroid function tests, and administration of the 12-Item Short Form Health Survey (SF-12) and the Patient Health Questionnaire-9 (PHQ-9) were performed before and after two weeks of THW. Regional homogeneity (ReHo), one of the measures of resting state FC, was calculated, and each voxel was compared between before and after THW in 19 patients. The ReHo values were extracted from the regions of interest showing within-group differences in ReHo values after THW, and correlations of ReHo values with thyrotropin (TSH) levels, total score of the PHQ-9, and composite scores of the SF-12 were statistically evaluated.

RESULTS

Higher ReHo was observed after THW in the brain cortical regions across primary motor and sensory, visual, and association cortices. Among the regions, the ReHo values in the bilateral pre- and postcentral gyri, bilateral middle occipito-temporal cortices, the left precuneus, and the left lingual gyrus showed positive correlations with serum TSH levels after THW. Higher ReHo values in the bilateral pre- and postcentral gyri, the left middle temporo-occipital cortices, and the left ligual gyrus correlated with the lower mental component summary score from the SF-12, while higher ReHo values in the bilateral pre- and postcentral gyri correlated with higher total scores in the PHQ-9.

CONCLUSIONS

Local brain FC is increased in the acute hypothyroid state. Higher FC correlates with a poorer mental QoL and increased depression in the hypothyroid state.

Subclinical Hypothyroidism and Type 2 Diabetes: A Systematic Review and Meta-Analysis

Background

Abundant evidence suggests an association between subclinical hypothyroidism (SCH) and type 2 diabetes mellitus (T2DM), but small sample sizes and inconclusive data in the literature complicate this assertion.

Objective

We measured the prevalence of SCH in T2DM population, and investigated whether T2DM increase the risk of SCH and whether SCH was associated with diabetic complications.

METHODS

We conducted a meta-analysis using PubMed, EMBASE, Web of Science, Wan Fang, CNKI and VIP databases for literature search. We obtained studies published between January 1, 1980 to December 1, 2014. The studies were selected to evaluate the prevalence of SCH in T2DM subjects, compare the prevalence of SCH in T2DM subjects with those non-diabetics, and investigate whether diabetic complications were more prevalent in SCH than those who were euthyroid. Fixed and random effects meta-analysis models were used, and the outcome was presented as a pooled prevalence with 95% confidence interval (95% CI) or a summary odds ratio (OR) with 95% CI.

RESULTS

Through literature search, 36 articles met the inclusion criteria and these articles contained a total of 61 studies. Funnel plots and Egger’s tests showed no publication bias in our studies, except for the pooled prevalence of SCH in T2DM (P = 0.08) and OR for SCH in T2DM (P = 0.04). Trim and fill method was used to correct the results and five potential missing data were replaced respectively. The adjusted pooled prevalence of SCH in T2DM patients was 10.2%, meanwhile, T2DM was associated with a 1.93-fold increase in risk of SCH (95% CI: 1.66, 2.24). Furthermore, SCH might affect the development of diabetic complications with an overall OR of 1.74 (95% CI: 1.34, 2.28) for diabetic nephropathy, 1.42 (95% CI: 1.21, 1.67) for diabetic retinopathy, 1.85 (95% CI: 1.35, 2.54) for peripheral arterial disease, and 1.87 (95% CI: 1.06, 3.28) for diabetic peripheral neuropathy.

Conclusions

T2DM patients are more likely to have SCH when compared with healthy population and SCH may be associated with increased diabetic complications. It is necessary to screen thyroid function in patients with T2DM, and appropriate individualized treatments in addition to thyroid function test should be given to T2DM patients with SCH as well.

Thyroid function testing in primary care: overused and under-evidenced? A study examining which clinical features correspond to an abnormal thyroid function result

BACKGROUND AND AIM

Diagnostic testing is increasing in primary care, including for thyroid disease. This study examined which clinical features were associated with an abnormal thyroid stimulating hormone (TSH) result.

DESIGN AND SETTING

This was a cross-sectional study in one general practice of 16,487 patients in Exeter, Devon, UK.

METHODS

We examined the primary care records relating to every TSH test taken in the year from August 2012, and extracted symptoms and/or the indication for testing. Associations with an abnormal result were tested using multivariable logistic regression. A cohort study was then performed of 100 patients newly recorded with each of the six features associated with an abnormal test result in the cross-sectional study, and the proportions tested for TSH and the results of that testing identified.

RESULTS

Two thousand thirty-five patients (12% of the practice population) had TSH testing in the year. Of these 35 (1.7%) had a TSH >4.5 mIU/l, suggesting hypothyroidism, and 7 (0.3%) had TSH <0.01 mIu/l suggesting hyperthyroidism. Features associated with an abnormal TSH were: pregnancy, odds ratio 41 (95% confidence interval 9.3-180), constipation 9.7 (2.1-45), palpitations 23 (3.4-150), hair loss, 21 (2.0-230), weight gain, 18 (1.6-190) and diarrhoea, 13 (1.2-130); in separate analyses only pregnancy and constipation were associated with a raised TSH, and the remaining four features with a low TSH.

CONCLUSION

The diagnostic yield of thyroid disease in this study was 2.1% suggests testing could be better targeted without missing diagnoses. The symptoms associated with thyroid disease differ from those generally reported. This may represent fewer patients presenting with advanced disease.

A high normal thyroid-stimulating hormone is associated with arterial stiffness, central systolic blood pressure, and 24-hour systolic blood pressure in males with treatment-naïve hypertension and euthyroid

BACKGROUND

We compared the results of laboratory examinations, echocardiography, arterial stiffness, central blood pressure (BP) and ambulatory BP monitoring (ABPM) between treatment-naïve patients with low normal thyroid-stimulating hormone (TSH) and those with high normal TSH levels.

METHODS

A total of 285 consecutively-eligible patients with both treatment-naïve hypertension and euthyroid were divided into two groups: those with low-normal TSH (0.40-1.99 μIU/mL, group 1) and high-normal TSH (2.00-4.50 μIU/mL, group 2) and compared according to group and gender.

RESULTS

Males were divided into group 1 (n = 113, 68.9%) and group 2 (n = 51, 31.1%) and females were divided into group 1 (n = 71, 58.7%) and group 2 (n = 50, 41.3%). Multivariate analyses revealed that the augmentation index (71.0 [adjusted mean] ± 1.7 [standard error] vs. 78.8 ± 2.5%, P = 0.045), central systolic BP (SBP) (143.3 ± 2.1 vs. 153.0 ± 3.2 mmHg, P = 0.013), systemic vascular resistance (SVR, 21.4 ± 0.6 vs. 23.9 ± 0.9 mmHg/L/min, P = 0.027), SBP during daytime (144.1 ± 1.4 vs. 151.6 ± 2.1 mmHg, P=0.004) and nighttime (130.4 ± 1.6 vs. 138.5 ± 2.5 mmHg, P=0.008), and nighttime pulse pressure (PP, 47.2 ± 0.9 vs. 51.7 ± 1.4 mmHg, P = 0.010) were significantly higher while cardiac output (5.4 ± 0.1 vs. 4.8 ± 0.2L/min, P = 0.043) and PP amplification (1.02 ± 0.02 vs. 0.94 ± 0.03, P = 0.039) were significantly lower in the male group 2 than in the male group 1. However, there were no significant differences between the two groups in females.

CONCLUSIONS

Treatment-naïve hypertensive males with high normal TSH and euthyroid showed higher arterial stiffness, central SBP, SVR, and SBP in ABPM and lower cardiac output and PP amplification as compared to the the low normal TSH group, but not females.

Effects of recombinant human thyrotropin administration on 24-hour arterial pressure in female undergoing evaluation for differentiated thyroid cancer

Objective. Thyroid-stimulating-hormone (TSH) receptors are expressed in endothelial cells. We investigated whether elevated TSH levels after acute recombinant TSH (rhTSH) administration may result in alterations in blood pressure (BP) in premenopausal women with well-differentiated thyroid carcinoma (DTC). Designs. Thirty euthyroid DTC female patients were evaluated by rhTSH stimulation test (mean age 40.4 ± 8.6 years). A 24 h ambulatory systolic and diastolic blood pressure (SBP, DBP) monitoring (24 hr ABPM) was performed on days 2-3(D2-3). TSH was measured on day 1(D1), day 3(D3), and day 5(D5). Central blood pressure was evaluated on D3. Twenty-three patients were studied 1-4 weeks earlier (basal measurements). Results. TSH levels were D1: median 0.2 mU/L, D3: median 115.0 mU/L, and D5: median 14.6 mU/L. There were no significant associations between TSH on D1 and D3 and any BP measurements. Median D5 office-SBP and 24 h SBP, DBP, and central SBP were correlated with D5-TSH (P < 0.04). In those where a basal 24 h ABPM had been performed median pulse pressure was higher after rhTSH-test (P = 0.02). Conclusions. TSH, when acutely elevated, may slightly increase SBP, DBP, and central SBP. This agrees with previous reports showing positive associations of BP with TSH.

Relation of hypothyroidism and incident atrial fibrillation (from the Framingham Heart Study)

BACKGROUND

Hyperthyroidism has a well-described association with atrial fibrillation (AF). However, the relation of hypothyroidism to AF has had limited investigation. Hypothyroidism is associated with cardiovascular risk factors, subclinical cardiovascular disease, and overt cardiovascular disease, all of which predispose to AF. We investigated 10-year incidence of AF in a community-dwelling cohort.

METHODS

Among 6,653 Framingham heart Study participants, 5,069 participants, 52% female, with mean age of 57 ± 12 years, were eligible after excluding those with missing thyroid-stimulating hormone (TSH), TSH <0.45 μU/L (hyperthyroid), TSH >19.9 μU/L, or prevalent AF. Thyroid-stimulating hormone was categorized by range (≥0.45 to <4.5, 4.5 to <10.0, 10.0 to ≤19.9 μU/L) and by quartiles. We examined the associations between TSH and 10-year risk of AF using multivariable-adjusted Cox proportional hazards analysis.

RESULTS

Over 10-year follow-up, we observed 277 cases of incident AF. A 1-SD increase in TSH was not associated with increased risk of AF (hazard ratio 1.01, 95% CI 0.90-1.14, P = .83). In categorical analysis, using TSH ≥0.45 to <4.5 μU/L as the referent (equivalent to euthyroid state), we found no significant association between hypothyroidism and 10-year AF risk. Comparing the highest (2.6 < TSH < 19.9 μU/L) to lowest (0.45 < TSH < 1.3 μU/L) quartiles of TSH further did not identify a significant association between TSH levels and 10-year risk of AF.

CONCLUSIONS

In conclusion, we did not identify a significant association between hypothyroidism and 10-year risk of incident AF in a community-based study.

Experimental gestational hypothyroidism evokes hypertension in adult offspring rats

Gestational hypothyroidism is a prevalent disorder in pregnant women. We aimed to investigate the impact of experimental gestational hypothyroidism (EGH) on cardiovascular and autonomic nervous systems (ANS) in the offspring of rats. EGH was induced with methimazole (MMI) 0.02% in drinking water from day 9 of gestation until birth. Sixty day old offspring from MMI-treated dams (OMTD, n=13) or water-treated dams (OWTD, n=13) had femoral arteries surgically assessed for the measurements of heart rate (HR), mean (MAP), systolic (SAP) and diastolic arterial pressure (DAP), and spontaneous baroreflex sensitivity (BRS). To investigate the balance of ANS, we established the high (HF) and low frequency (LF) bands of pulse interval (PI) and LF band of SAP spectrum. OMTD had increased MAP (130.2 ± 2.0 vs 108.8 ± 3.0 mmHg, p<0.001), SAP (157.3 ± 2.9 vs 135.7 ± 4.5mm Hg, p<0.001) and DAP (109.7 ± 1.9 vs 88.4 ± 2.6 mmHg, p<0.001) when compared to OWTD, and had lower HR (355.1 ± 8.9 vs 386.8 ± 9.2 bpm, p<0.05). After spectral analysis of PI and SAP, only LF band of SAP spectrum was higher (7.2 ± 0.8 vs 4.0 ± 0.6 mmHg(2), p<0.01) in OMTD under spontaneous condition. Despite bradycardia, EGH promotes spontaneous hypertension in 60 day old offspring, probably due to increased sympathetic modulation of vessels, which is suggested by the higher LF of SAP. These findings suggest a critical role of maternal THs in the development of fetal cardiovascular and autonomic nervous systems.

Investigation of thyroid function and blood pressure in school-aged subjects without overt thyroid disease

This study was performed to ascertain whether a relationship exists between thyroid function and blood pressure in school-aged Chinese subjects without overt thyroid disease. A cross-sectional survey of 880 subjects (541 females and 339 males) aged 7-18 years in Bengbu, Anhui province was conducted. The investigation, which was based on a stratified random cluster sampling method, included a questionnaire and measurements of blood pressure, height, and body weight. Fasting blood samples were taken for measurements of thyroid-stimulating hormone (TSH), free 3,5,3'-triiodothyronine (FT(3)) and free thyroxine (FT(4)). Serum TSH and FT(3) were positively correlated with systolic and diastolic blood pressure Z scores (SBP-Z and DBP-Z) even after adjusting for body mass index (BMI) (P < 0.05) but no correlation was observed between FT(4) and SBP-Z or DBP-Z after comparable adjustments (P > 0.05). SBP-Z and DBP-Z in subjects with subclinical hypothyroidism were significant higher than in euthyroid subjects (P < 0.05). Both SBP-Z and DBP-Z increased linearly with TSH concentration in boys after adjusting BMI (P < 0.05); however, a similar linear trend was not observed in girls. Our findings support the hypothesis that elevated TSH and FT(3) concentrations increase blood pressure in school-aged Chinese subjects without overt thyroid disease; this increase may be even more significant in boys.

Blood pressure, thyroid-stimulating hormone, and thyroid disease prevalence in primary aldosteronism and essential hypertension

BACKGROUND

A positive correlation between thyroid-stimulating hormone (TSH) and blood pressure (BP) has been identified in normotensives and in patients with essential hypertension (EH). This study was designed to evaluate, in primary aldosteronism (PA) and in EH, potential association of BP, TSH, and ultrasonographic changes of the thyroid.

METHODS

We studied 188 patients: 92 with PA and 96 matched essential hypertensives. Clinical and ambulatory BP (ABP), and thyroid function were evaluated in all patients. In PA and in a subgroup of EH patients (n = 65) thyroid ultrasonography was performed.

RESULTS

In PA patients, diastolic office and diastolic ABP increased across TSH quartiles and multivariate analysis confirmed a positive significant correlation between TSH and diastolic BP, independently of aldosterone levels, body mass index (BMI), duration of hypertension, and age. In EH patients, we found a significant linear increase in systolic and diastolic ABP with increasing TSH. The prevalence of thyroid dysfunctions was similar in PA and EH (15% and 19%, respectively). In PA patients, we found a higher prevalence of ultrasonographic alterations than in EH (66% vs. 46%, P < 0.05). PA patients presenting morphological abnormalities had higher homeostasis model assessment-insulin resistance levels than patients with normal gland at ultrasonography (4.2 ± 1.8 vs. 3.1 ± 0.8 P < 0.05).

CONCLUSIONS

We found a positive correlation between TSH and BP both in PA and EH patients. Moreover, in PA patients we observed a high prevalence of thyroid morphological alterations.

Serum thyrotropin levels and blood pressure response to exercise in a population-based study

BACKGROUND

Studies on the relation between thyroid function and exercise blood pressure (EBP) are rare and not population-based, and have yielded inconsistent results. The aim of this study was to investigate whether serum thyrotropin (TSH) levels are related to increased EBP.

METHODS

Cross-sectional data from 1438 subjects (711 women) aged 25-83 years without histories of cardiovascular diseases from the 5-year follow-up of the population-based Study of Health in Pomerania (SHIP-1) were analyzed. Blood pressure was measured at the 100 W stage of a symptom-limited bicycle ergometry test. Increased EBP was defined as a value above the sex- and age-specific 80th percentile of participants with serum TSH levels within the reference range (0.25-2.12 mIU/L).

RESULTS

There was no association between serum TSH levels and EBP after adjusting for sex, age, waist circumference, diabetes mellitus, smoking status, and antihypertensive medication. The odds for increased systolic EBP (odds ratio 1.24, 95% confidence interval 0.88; 1.76) and diastolic EBP (odds ratios 0.98, 95% confidence interval 0.70; 1.39) as well as for exercise-induced increase of systolic and diastolic blood pressure were not significantly different between subjects with high and low serum TSH levels within the reference range. Similar findings were found for both subjects with TSH levels below and above the reference range, respectively.

CONCLUSIONS

We conclude that serum TSH levels are not associated with exercise-related blood pressure response.

Lipid abnormalities and cardiometabolic risk in patients with overt and subclinical thyroid disease

Dyslipidemia is a common finding in patients with thyroid disease, explained by the adverse effects of thyroid hormones in almost all steps of lipid metabolism. Not only overt but also subclinical hypo- and hyperthyroidism, through different mechanisms, are associated with lipid alterations, mainly concerning total and LDL cholesterol and less often HDL cholesterol, triglycerides, lipoprotein (a), apolipoprotein A1, and apolipoprotein B. In addition to quantitative, qualitative alterations of lipids have been also reported, including atherogenic and oxidized LDL and HDL particles. In thyroid disease, dyslipidemia coexists with various metabolic abnormalities and induce insulin resistance and oxidative stress via a vice-vicious cycle. The above associations in combination with the thyroid hormone induced hemodynamic alterations, might explain the increased risk of coronary artery disease, cerebral ischemia risk, and angina pectoris in older, and possibly ischemic stroke in younger patients with overt or subclinical hyperthyroidism.

Hypothyroidism and hypertension

Hypothyroidism has been recognized as a cause of secondary hypertension. Previous studies on the prevalence of hypertension in subjects with hypothyroidism have demonstrated elevated blood pressure values. Increased peripheral vascular resistance and low cardiac output has been suggested to be the possible link between hypothyroidism and diastolic hypertension. The hypothyroid population is characterized by significant volume changes, initiating a volume-dependent, low plasma renin activity mechanism of blood pressure elevation. This article summarizes previous studies on the impact of hypothyroidism on blood pressure and early atherosclerotic process.

Short-term overt hypothyroidism induces discrete diastolic dysfunction in patients treated for differentiated thyroid carcinoma

BACKGROUND

Thyroid hormone has important effects on the cardiovascular system. The consequences of episodes of acute hypothyroidism on cardiac function have been investigated in only a few studies, and their results are inconclusive. Our objective was to investigate the effects of acute hypothyroidism on cardiac function in patients with iatrogenically induced subclinical hyperthyroidism after treatment for differentiated thyroid carcinoma.

MATERIAL AND METHODS

Fourteen patients with a history of differentiated thyroid carcinoma on thyroid-stimulating hormone (TSH)-suppressive thyroxine replacement therapy were studied. We assessed cardiac function before, and 1 and 4 weeks after withdrawal of thyroxine substitution. We measured serum levels of free thyroxine, triiodothyronine and TSH and used a new sophisticated Doppler echocardiography technique, tissue Doppler imaging (TDI), to assess detailed and quantitative assessment of systolic and diastolic cardiac function. Echocardiographic parameters in patients were compared to controls.

RESULTS

Compared to controls, patients had higher left ventricular mass and wall thickness and decreased diastolic function during TSH-suppressive l-thyroxine substitution therapy. Thyroxine withdrawal resulted in a decrease in both early (E) and late (A) diastolic mitral inflow velocities, without impact on E/A ratio. Using TDI, late diastolic velocity (A') decreased without impact on E'/A' ratio. Left ventricular dimensions, wall thickness and mass did not change during thyroxine withdrawal.

CONCLUSIONS

Subclinical hyperthyroidism is accompanied by diastolic dysfunction. Subsequent acute hypothyroidism induces only subtle changes in diastolic function.

Association of thyroid function with arterial pressure in normotensive and hypertensive euthyroid individuals: A cross-sectional study

Background

Overt hypothyroidism has been associated with arterial hypertension and increased arterial stiffness. Results in euthyroid individuals have been conflicting. We investigated associations of thyroid function with systolic (SAP) and diastolic (DAP) arterial pressure in euthyroid subjects.

Methods

311 euthyroid individuals (185 women, mean age 43.9 ± 9) without a history of diabetes attending a preventive medicine program were examined. Subjects receiving thyroxine (10.6%) were excluded; 19.3% had hypertension, 43% had a family history for hypertension. TSH, fT4, thyroid autoantibodies, insulin, glucose were measured. The "fT4.TSH product", which has been suggested as a T4 resistance-index, was calculated.

Results

TSH range was 0.1–8, median 1.4 mU/L, fT4 range was 11.5–25.2 pmol/L, median 17.4. TSH and the "fT4.TSH product" were positively associated with DAP (p < 0.03, for both associations). In the subgroup of individuals with TSH levels 0.36–2.5 mU/L, both TSH and the "fT4.TSH product" were positively correlated with SAP (r = +0.133 p = 0.044, r = +0.152 p = 0.026) and DAP (r = +0.243 p < 0.001, r = +0.252 p < 0.001 respectively); in multivariate analysis the "fT4.TSH product" was a significant predictor of DAP independently of HOMA-IR and BMI (p < 0.001). Similar associations were found when only the non-hypertensive subjects were analysed (p = 0.004). Hypertensive patients had higher TSH levels (p = 0.02) and belonged more frequently to the subgroup with TSH > 2 mU/L (35.3% vs 21.3%, p = 0.045).

Conclusion

In euthyroid individuals the association of thyroid function with diastolic arterial pressure remains significant even when a stricter "normal range" for TSH levels is considered. The "freeT4.TSH" product appears to be an even stronger predictor of DAP, independently of HOMA insulin resistance index and obesity.