Prevalence and follow-up of abnormal thyrotrophin (TSH) concentrations in the elderly in the United Kingdom

Subclinical Hyperthyroidism and Cardiovascular Disease

Background: In this narrative review, we assess published data on subclinical hyperthyroidism (SCHyper) and its association with cardiovascular disease (CVD) in the general population. Summary: We present data on the risk of SCHyper in relation to CVD outcomes, including atrial fibrillation (AF), heart failure, stroke, coronary heart disease (CHD), major adverse cardiac events (MACE), CVD mortality, and all-cause mortality. Evidence indicates that SCHyper is associated with an elevated risk of AF, heart failure, MACE, CVD mortality, and all-cause mortality. SCHyper appears to have little association with stroke risk and has shown conflicting results regarding CHD risk. Regarding the degree of serum TSH suppression, evidence shows a higher risk of CVD in SCHyper individuals with suppressed TSH (<0.1 mIU/L) compared with those with low TSH (0.1-0.4 mIU/L). Despite evidence that older individuals are inherently at a higher risk for CVD, no studies have yet demonstrated an age-related increase in the relative risk of CVD in SCHyper. Conclusion: The studies indicate that SCHyper is associated with an increased risk of AF, heart failure, MACE, CVD mortality, and all-cause mortality. Considering the importance of the degree of serum TSH suppression and age as risk factors for CVD, treatment decisions should be individualized based on their specific risk factors.

Hypothyroidism

Hypothyroidism, the deficiency of thyroid hormone, is a common condition worldwide. It affects almost all body systems and has a wide variety of clinical presentations from being asymptomatic to, in rare cases, life threatening. The classic symptoms of hypothyroidism include fatigue, lethargy, weight gain, and cold intolerance; however, these symptoms are non-specific and the diagnosis is typically made on biochemical grounds through serum thyroid function tests. The most common cause of hypothyroidism is chronic autoimmune thyroiditis (Hashimoto's thyroiditis), although other causes, including drugs (such as amiodarone, lithium, and immune checkpoint inhibitors), radioactive-iodine treatment, and thyroid surgery, are frequent. Historically, severe iodine deficiency was the most common cause. Reference ranges for thyroid function tests are based on fixed percentiles of the population distribution, but there is increasing awareness of the need for more individualised reference intervals based on key factors such as age, sex, and special circumstances such as pregnancy. Levothyroxine monotherapy is the standard treatment for hypothyroidism; it is safe and inexpensive, restores thyroid function tests to within the reference range, and improves symptoms in the majority of patients. However, 10% of patients have persistent symptoms of ill health despite normalisation of thyroid function tests biochemically and a substantial proportion of patients on levothyroxine have thyroid-stimulating hormone concentrations outside the reference range. Ongoing symptoms despite levothyroxine treatment has led to some patients using liothyronine or desiccated thyroid extract. Taken together, these factors have led to intense debate around the treatment thresholds and treatment strategies for hypothyroidism. In this Seminar, we review the epidemiology, genetic determinants, causes, and presentation of hypothyroidism; highlight key considerations and controversies in its diagnosis and management; and provide future directions for research.

The role of non-invasive oscillometric method to detect aortic stiffness in patients with subclinical hypothyroidism

INTRODUCTION

Subclinical hypothyroidism (SCH) is a biochemical condition that is diagnosed when peripheral free thyroid hormone levels are within normal reference laboratory range but serum thyroid-stimulating hormone (TSH) levels are mildly elevated. The aim of this study was to investigate the relationship between SCH and arterial stiffness using two different non-invasive methods, including echocardiography and oscillometric arteriography.

MATERIAL AND METHODS

The study included 33 newly diagnosed SCH patients and 34 age- and gender-matched healthy controls. Systolic and diastolic diameters and elastic parameters of the aorta were calculated by 2D Transthoracic echocardiography (TTE). Central blood pressure and aortic stiffness values of patient groups were measured noninvasively from the brachial artery using Mobil-O-Graph arteriography. Pulse wave velocity (PWV) and augmentation index (AIx) were used as arterial stiffness indicators.

RESULTS

There was no significant difference between SCH and control groups with regard to age, gender, and body mass index (BMI). Aortic strain and aortic distensibility, were significantly lower in the SCH group than in the control group (p < 0.001). PWV and AIx which measured by Mobil-O-Graph arteriography were found to be significantly higher in the subclinical hypothyroid group compared to the control group (p < 0.05).

CONCLUSION

Aortic stiffness assessed by TTE and Mobil-O-Graph arteriography deteriorated in patients with SCH after excluding other cardiovascular risk factors. The assessment of aortic stiffness by the oscillometric method was easy and useful for widespread clinical use.

Patient-Reported Satisfaction with Thyroid Hormone Replacement Therapy for Subclinical Hypothyroidism in Older Adults: A Pooled Analysis of Individual Participant Data from Two Randomized Controlled Trials

Background: The benefit of levothyroxine treatment of subclinical hypothyroidism (SCH) is subject to debate. This study compared treatment satisfaction between older adults with SCH using levothyroxine or placebo. Methods: We analyzed pooled individual participant data from two randomized, double-blind, placebo-controlled trials investigating the effects of levothyroxine treatment in older adults with SCH. Community-dwelling participants aged ≥65 years, with SCH (persistent thyrotropin levels 4.60-19.99 mIU/L for >3 months and normal free T4 level), were included. Intervention dose titration until thyrotropin levels normalized, with a mock dose adjustment of placebo. Treatment satisfaction was determined during the final study visit using the Treatment Satisfaction Questionnaire for Medication (TSQM), encompassing perceived effectiveness, side effects, convenience, and global satisfaction, along with the participants' desire to continue study medication after the trial. Results: We included 536 participants. At baseline, the median (interquartile range [IQR]) age was 74.9 (69.7-81.4) years, and 292 (55%) were women. The median (IQR) thyrotropin levels were 5.80 (5.10-7.00) mIU/L at baseline in both groups; at final visit, 4.97 (3.90-6.35) mIU/L in the placebo and 3.24 (2.49-4.41) mIU/L in the levothyroxine group. After treatment, the groups did not differ significantly in global satisfaction (mean difference [CI] -1.1 [-4.5 to 2.1], p = 0.48), nor in any other domain of treatment satisfaction. These results held true regardless of baseline thyrotropin levels or symptom burden. No major differences were found in the numbers of participants who wished to continue medication after the trial (levothyroxine 35% vs. placebo 27%), did not wish to continue (levothyroxine 27% vs. placebo 30%), or did not know (levothyroxine 37% vs. placebo 42%) (p = 0.14). In a subpopulation with high symptom burden from hypothyroid symptoms at baseline, those using levothyroxine more often desired to continue the medication after the trial than those using placebo (mean difference [CI]: -21.1% [-35.6% to -6.5%]). Conclusion: These pooled data from two RCTs showed no major differences in treatment satisfaction between older adults receiving levothyroxine or placebo. This finding has important implications for decision-making regarding initiating levothyroxine treatment for SCH. Our findings generally support refraining from routinely prescribing levothyroxine in older adults with SCH.

Triiodothyronine/Thyroxine Ratio as a Marker of Clinical Response to Levothyroxine Replacement in Patients With Hypothyroidism

BACKGROUND

 Hypothyroidism is one of the most common endocrine disorders with a simple therapy, that is levothyroxine (LT4). A normal thyroid-stimulating hormone (TSH) measurement is used as a marker of optimal replacement. But, many patients still have symptoms. Triiodothyronine (T3), thyroxine (T4), and their ratio may correlate with clinical improvement. The study aims to assess the T3/T4 ratio as a marker of clinical response in patients with hypothyroidism.  Method: A cross-sectional study was conducted from June to November 2022 at Faiha Specialized Diabetes, Endocrine, and Metabolism Center, in Basrah, southern Iraq. We included 48 adult patients with primary hypothyroidism on LT4 treatment only and TSH within the target reference range for at least within the last six months. Each patient was subjected to a questionnaire that was designed to capture hypothyroidism-related complaints in the form of a five-point Likert scale. Biochemical assessments were done with the measurement of TSH, T3, and T4.

RESULTS

Despite having a normal TSH level, nearly all the patients had persistent and varying severity of clinical complaints of hypothyroidism. Tiredness, hair problems, weight gain, and cold intolerance were the most severely persistent symptoms. Patients with scores of two and more for weight gain, cold intolerance, and skin problems had significantly lower T3/T4 ratios (P = 0.04, 0.002, and 0.02, respectively), while in the remaining clinical symptoms, the T3/T4 ratio did not differ significantly.

CONCLUSION

A low T3/T4 ratio was significantly associated with resistant symptoms of hypothyroidism and may be used as a marker for treatment efficacy with TSH rather than TSH value alone.

Relationship between Thyroid CT Density, Volume, and Future TSH Elevation: A 5-Year Follow-Up Study

This study aimed to explore the relationship between thyroid-stimulating hormone (TSH) elevation and the baseline computed tomography (CT) density and volume of the thyroid. We examined 86 cases with new-onset hypothyroidism (TSH > 4.5 IU/mL) and 1071 controls from a medical check-up database over 5 years. A deep learning-based thyroid segmentation method was used to assess CT density and volume. Statistical tests and logistic regression were employed to determine differences and odds ratios. Initially, the case group showed a higher CT density (89.8 vs. 81.7 Hounsfield units (HUs)) and smaller volume (13.0 vs. 15.3 mL) than those in the control group. For every +10 HU in CT density and -3 mL in volume, the odds of developing hypothyroidism increased by 1.40 and 1.35, respectively. Over the course of the study, the case group showed a notable CT density reduction (median: -8.9 HU), whereas the control group had a minor decrease (-2.9 HU). Thyroid volume remained relatively stable for both groups. Higher CT density and smaller thyroid volume at baseline are correlated with future TSH elevation. Over time, there was a substantial and minor decrease in CT density in the case and control groups, respectively. Thyroid volumes remained consistent in both cohorts.

A machine learning-assisted system to predict thyrotoxicosis using patients' heart rate monitoring data: a retrospective cohort study

Previous studies have shown a correlation between resting heart rate (HR) measured by wearable devices and serum free thyroxine concentration in patients with thyroid dysfunction. We have developed a machine learning (ML)-assisted system that uses HR data collected from wearable devices to predict the occurrence of thyrotoxicosis in patients. HR monitoring data were collected using a wearable device for a period of 4 months in 175 patients with thyroid dysfunction. During this period, 3 or 4 thyroid function tests (TFTs) were performed on each patient at intervals of at least one month. The HR data collected during the 10 days prior to each TFT were paired with the corresponding TFT results, resulting in a total of 662 pairs of data. Our ML-assisted system predicted thyrotoxicosis of a patient at a given time point based on HR data and their HR-TFT data pair at another time point. Our ML-assisted system divided the 662 cases into either thyrotoxicosis and non-thyrotoxicosis and the performance was calculated based on the TFT results. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of our system for predicting thyrotoxicosis were 86.14%, 85.92%, 52.41%, and 97.18%, respectively. When subclinical thyrotoxicosis was excluded from the analysis, the sensitivity, specificity, PPV, and NPV of our system for predicting thyrotoxicosis were 86.14%, 98.28%, 94.57%, and 95.32%, respectively. Our ML-assisted system used the change in mean, relative standard deviation, skewness, and kurtosis of HR while sleeping, and the Jensen-Shannon divergence of sleep HR and TFT distribution as major parameters for predicting thyrotoxicosis. Our ML-assisted system has demonstrated reasonably accurate predictions of thyrotoxicosis in patients with thyroid dysfunction, and the accuracy could be further improved by gathering more data. This predictive system has the potential to monitor the thyroid function status of patients with thyroid dysfunction by collecting heart rate data, and to determine the optimal timing for blood tests and treatment intervention.

Assessing the cardiovascular effects of levothyroxine use in an ageing United Kingdom population (ACEL-UK) protocol: a cohort and target trial emulation study

BACKGROUND

Subclinical hypothyroidism is diagnosed when serum thyroid stimulating hormone levels are higher whilst free thyroxine levels remain within their respective reference ranges. These reference ranges are uniformly applied in all adults, despite serum thyroid stimulating hormone levels naturally increasing with age. Research has found that mildly elevated thyroid stimulating hormone levels may be associated with some benefits in ageing patients, including reduced mortality and better cardiorespiratory fitness. Levothyroxine is typically prescribed to patients with hypothyroidism, but no conclusive evidence exists on whether levothyroxine therapy is beneficial or detrimental in older subclinical hypothyroid patients. Despite this, prescriptions for levothyroxine are increasing year-on-year. This study aims to determine if receiving levothyroxine affects the cardiovascular and bone health outcomes of subclinical patients in primary care aged 50 years and over.

METHODS

This project includes a retrospective cohort analysis and a target trial emulation study using electronic patient records collected between 2006 and 2021 and recorded in The Health Improvement Network database. The primary outcome of this study is to compare the cardiovascular outcomes of subclinical hypothyroid patients aged over 50 years treated with levothyroxine compared to those untreated. Secondary outcomes are bone health and all-cause mortality outcomes. Descriptive and inferential statistics will both be employed to analyse the data. Secondary analysis will explore confounding factors, including age, sex, smoking status, body mass index, co-morbidities, and levothyroxine dosage.

DISCUSSION

There needs to be a greater understanding of the potential risks of the current treatment for older patients with subclinical hypothyroidism in a primary care setting. We will investigate the clinical importance of this issue and whether older subclinical hypothyroid patients have poorer outcomes when treated. Clarifying this concern may help address the healthcare resource implications of ageing patients being misclassified as having mild hypothyroidism, as these patients are more likely to repeat their blood tests. This could reduce prescription wastage and improve patient outcomes and quality of life in the ageing population.

TRIAL REGISTRATION

Not applicable.

Increased 10-year cardiovascular disease risk in depressed patients with coexisting subclinical hypothyroidism

Purpose

The prevalence of depressive disorder (DD) and subclinical hypothyroidism (SH) was almost twofold higher in women compared with men, both of which are confirmed to be related to cardiovascular disease (CVD) risk. The current study aimed to identify the prevalence of CVD risk factors and evaluate the 10-year CVD risk in female depressed patients with and without comorbid SH.

Methods

We recruited 1744 female inpatients with a diagnosis of DD. Venous blood samples were taken from all patients for lipid and thyroid hormones. Framingham Risk Score (FRS) was used to estimate the 10-year CVD risk.

Results

Female depressed patients with SH had increased BMI, higher Hamilton Anxiety Scale (HAMA) scores, higher LDL-C, TC, UA, and a higher 10-year CVD risk than euthyroid DD groups. Serum TSH levels and HAMA scores were critical predictive variables for 10-year CVD risk in female depressed patients with comorbid SH.

Conclusion

Our study suggests that female depressed patients with SH have a high 10-year CVD risk. Serum TSH levels and HAMA scores may be helpful to predict cardiovascular risk in female patients with SH. The increased CVD risk in female depressed patients with comorbid SH requires more attention from researchers and clinicians.

The management and metabolic characterization: hyperthyroidism and hypothyroidism

Hyperthyroidism and hypothyroidism are common diseases resulting from thyroid dysfunction, and are simple to diagnose and treat. The traditional treatment for hypothyroidism is thyroid hormone replacement therapy. The traditional treatments for hyperthyroidism include antithyroid drug, iodine radiotherapy, and surgery. Thyroid disease can be fatal in severe cases if untreated. Current statistical reference ranges used for diagnosis based on relevant biochemical parameters have been debated, and insufficient treatment can result in long-term thyroid hormone deficiency, which is associated with increased risk of cardiovascular disease and persistent symptoms. In contrast, overtreatment can result in heart disease and osteoporosis, particularly in older people and pregnant women. Therefore, under- or over-treatment should be avoided and treatment regimens should be monitored closely. A significant proportion of patients who achieve biochemical treatment goals still complain of significant symptoms. Systematic literature review was performed through the Embase (Elsevier), PubMed and Web of Science databases, and studies summarized evidence regarding treatment and management of hypothyroidism and hyperthyroidism, and reviewed clinical practice guidelines. We also reviewed the latest research on the metabolic mechanisms of hyperthyroidism and hypothyroidism, which contributed to understanding of thyroid diseases in the clinic. A reliable algorithm is needed to management, assessment, and treatment patients with hyperthyroidism and hypothyroidism, which can not only improve management efficiency, but also providing a broad application. In addition, the thyroid disorder showed a lipid metabolism tissue specificity in the Ventromedial Hypothalamus, and effect oxidative stress and energy metabolism of whole body. This review summarizes an algorithm for thyroid disease and the latest pathogenesis that would be useful to generalist and subspecialty physicians and others providing care for patients with this condition.

Approach to the Patient With a Suppressed TSH

Subclinical hyperthyroidism (SCH) is a laboratory diagnosis defined by a serum thyrotropin (TSH) concentration below the reference range (< 0.4 mU/L in most assays), and a free thyroxine (FT4) and 3,5,3'-triiodothyronine levels (FT3) in the reference range. Many patients diagnosed with SCH will be clinically euthyroid while others may present with manifestations characteristic of thyroid hormone excess, such as tachycardia, tremor, intolerance to heat, bone density loss, or weight loss. In addition to the laboratory abnormalities, patient factors such as age, symptoms, and underlying heart and bone disease are used to stratify patients for the risk of adverse outcomes and determine the appropriate treatment. Evaluation should include repeat thyroid function tests to document persistent TSH suppression, investigation of the underlying cause, as well as evaluation of the patient's risk of adverse outcomes in the setting of a subnormal TSH. Persistent SCH has been associated with an increased risk of a range of adverse events, including cardiovascular events such as atrial fibrillation and heart failure, bone loss and fracture, and in some studies, cognitive decline. Despite the consistent association of these adverse events with SCH, prospective studies showing improved outcomes with treatment remain limited. Management options include observation without active therapy, radioactive iodine ablation of the thyroid, antithyroid medication, thyroid surgery, or radiofrequency ablation, as appropriate for the patient and clinical setting. The choice of therapy should be guided by the underlying etiology of disease, patient factors, and the risks and benefits of each treatment option.

Natural history of subclinical hypothyroidism and prognostic factors for the development of overt hypothyroidism: Tehran Thyroid Study (TTS)

OBJECTIVE

The significance of subclinical hypothyroidism (SCH) is largely due to its potential risk for developing overt hypothyroidism (OH). Investigations are still exploring predictive factors contributing to the progression of SCH to OH, particularly in patients with mildly elevated serum thyrotropin (TSH). We aimed to clarify the natural history of SCH and the predictive factors of its progression, based on the grade of SCH severity.

METHODS

This study was conducted within the framework of the Tehran Thyroid Study (TTS), in which 5783 individuals aged ≥ 20 years were followed. After applying exclusion criteria, data of 270 SCH subjects remained for the analysis. Thyroid function tests were assessed at baseline and every 3 years.

RESULTS

Of 270 participants with SCH, 239 (88.5%) had TSH level between 5.06 and 10 mU/L, and 31 (11.4%) had TSH ≥ 10 mU/L. During a median follow-up of 10 years, 40% had TSH within the reference range, 44% maintained elevated TSH, and 16% had added low T4 to the elevated TSH. The annual incidence rate of progression to OH was 22.3 (16.5-101.9) per 1000 person-years [18 (12.6-25.6) for those with TSH 5.07-9.9 mU/L and 57.8 (22.8-101.9) for patients with TSH ≥ 10 mU/L per 1000 person-years (P = 0.001)]. After adjusting age, sex, body mass index (BMI), thyroid peroxidase antibody (TPOAb), and serum TSH, only TPOAb positivity (HR: 2.31; 95% CI 1.10-4.83, P = 0.026) and baseline TSH level ≥ 10 mU/L (HR: 5.14; 95% CI 2.14-12.3, P < 0.001) remained as predictors for development of OH. In patients with TSH 5.07-9.9 mU/L, TPOAb positivity was associated with an increased risk of OH (HR: 2.41; 95% CI 1.10-5.30, P = 0.027). However, in patients with TSH ≥ 10 mU/L, TPOAb positivity was not a predictor (P = 0.49).

CONCLUSION

TPOAb and not TSH are associated with the development of OH in individuals with serum TSH below 10 mU/L, and follow-up at regular intervals is recommended in TPOAb-positive individuals with TSH between 5 and 10 mU/L.

The role of systemic immune activation in the development of thyroid dysfunction in COVID-19

Background. The research of cytokine-induced thyropathies in the midst of continuing coronavirus infection (COVID-19) pandemic is a very important and urgent problem. On the one hand, COVID-19 is often accompanied by a massive overproduction of cytokines, so we can expect an enhanced cytokines effects impact on the thyroid gland. On the other hand, it is possible that biological therapy with tocilizumab, which has a powerful immunosuppressive effect, plays a protective role to the development of cytokines-induced thyropathies amidst COVID-19. The results of the study should be the starting point for understanding the mechanisms of possible compromise of thyroid function during COVID-19. Aim. The primary endpoint is to assess the relationship between the levels of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4) with the inflammatory process markers. The secondary endpoint is the identification of an association between TSH, FT3 and FT4 values, and patient survival. Materials and methods. This retrospective, single-center study included 122 patients hospitalized at the National Medical Research Center for Endocrinology with a clinical and laboratory analysis of COVID-19 and bilateral polysegmental viral pneumonia. To assess the functional status of the thyroid gland all patients underwent observation of the TSH, FT3, FT4, antibodies to thyroid peroxidase, antibodies to the TSH receptor (AT-recTSH). The markers of the inflammatory process were assessed: interleukin-6, C-reactive protein, the degree of lung tissue damage according to multispiral computed tomography of the lungs, the percentage of blood oxygen saturation (SpO2), the treatment outcomes. Results. Five (4%) patients were found with subclinical thyrotoxicosis. Serum TSH values were inversely correlated with interleukin-6 (r=-0.221; p=0.024). Analysis of the level of hospital mortality, stratified by TSH, revealed statistically significantly lower TSH values in the group of deceased patients (p=0.012). The median TSH in surviving patients was 1.34 [0.85; 1.80], for the deceased 0.44 [0.29; 0.99]. Conclusion. Our research shows that the trigger of thyropathies in coronavirus infection is most likely thyroid tissue damage by the proinflammatory cytokines. This study shows some specific clinical aspects regarding the clinical relevance in patients with thyrotoxicosis and COVID-19, namely, the high hospital mortality rate.

Hypothyroidism has a protective causal association with hepatocellular carcinoma: A two-sample Mendelian randomization study

Objective

Observational studies suggest an association between hypothyroidism and the risk of hepatocellular carcinoma (HCC), but the causality and direction of these effects are still inconclusive. We aim to test whether hypothyroidism is causally associated with the risk of HCC by using Mendelian randomization (MR) analysis.

Methods

Single-nucleotide polymorphisms (SNPs) associated with hypothyroidism were screened via a genome-wide association study (GWAS) on 337,159 individuals of European descent (16,376 cases and 320,783 controls). The SNPs associated with thyroid-stimulating hormone (TSH) and free thyroxine (FT4) were selected from a GWAS of 72,167 individuals of European descent. Summary-level data for HCC (168 cases and 372,016 controls) were extracted from UK Biobank. An inverse-variance-weighted (IVW) method was used as the primary MR analysis. Sensitivity analyses were examined via MR-Egger regression, heterogeneity test, pleiotropy test, and leave-one-out sensitivity test. The assumption that exposure causes outcome was verified using the MR Steiger test.

Results

Two-Sample MR analysis showed inverse associations between genetically predicted hypothyroidism and HCC risk (OR = 0.997, 95% CI, 0.995-0.999; P = 0.016). There were no statistical indications of heterogeneity among instruments (P-het = 0.667). Across five MR methods, genetically predicted hypothyroidism shows a consistent correlation with HCC. The leave-one-out analysis indicated that no single SNP changed the overall estimate (P = 0.016). In addition, the MR Steiger test revealed that hypothyroidism was causal for HCC and not the opposite (P = 0.000). Finally, there was no evidence for a direct causal effect of TSH level and FT4 level on HCC risk.

Conclusion

Our results provide some that genetically determined hypothyroidism decreases the risk of HCC, although the size of the causal estimate is small. Further research is required to comprehend the mechanisms underlying this putative causative association, and follow-up clinical trials need to be conducted to establish whether inducing hypothyroidism could be beneficial for patients who are suffering from HCC. During future treatment of hypothyroidism, close attention to liver function may also be required to prevent a possible increased risk of HCC.

Subclinical hypothyroidism in women's health: from pre- to post-menopause

OBJECTIVE

Subclinical hypothyroidism (SCH) is a quite frequent condition among women, affecting 3-12% of the general population. Its consequences on women's health in reproductive age, pregnancy and menopause have been extensively investigated but data about the effective impact of treatment with levothyroxine (LT4) remain conflicting.

METHODS

This is a narrative review and analysis of the most relevant data until June 2021.

RESULTS

SCH may affect reproduction. Evidence suggests that women with SCH undergoing assisted reproductive technique (ART) may benefit from LT4 therapy whereas there are no conclusive data regarding women attempting natural conception. SCH may be associated with several negative pregnancy outcomes, that is to say recurrent pregnancy loss (RPL), preterm delivery, preeclampsia and neurocognitive disturbances of offspring. However, the protective role of LT4 treatment has been established in selected cases, for instance in thyroid peroxidase antibody (TPOAb) -positive women with TSH greater than the pregnancy specific reference range and/or in TPOAb-negative women with TSH >10.0 mIU/L. In menopause, SCH can worsen the negative cardio-metabolic effects of hormonal loss and/or aging, by exacerbating dyslipidaemia and hypertension. Nevertheless, robust data about the benefits of LT4 therapy are still lacking and treatment should be encouraged with caution.

CONCLUSIONS

SCH represents a challenging condition during pre- and post- menopause. An aware knowledge of its possible principal consequences could help all clinicians who are involved in women's health to manage more properly it, preventing its sequelae.

Thyroid stimulating hormone suppression and recurrence after thyroid lobectomy for papillary thyroid carcinoma

BACKGROUND

Thyroid lobectomy is recommended as the primary treatment for low-risk thyroid cancer. However, recurrence and hypothyroidism may develop after lobectomy, necessitating thyroid hormone supplementation. The 2015 American Thyroid Association (ATA) guidelines recommended post-lobectomy thyroid-stimulating hormone (TSH) suppression. This study examined the need for TSH suppression and recurrence after lobectomy for unilateral papillary thyroid carcinoma (PTC).

METHODS

This study involved 369 patients who underwent thyroid lobectomy and ipsilateral central neck dissection for PTC between 2007 and 2015. Thyroid function tests were performed before and regularly after lobectomy. Binary logistic regression analyses were used to find factors predictive of the post-lobectomy need for TSH suppression that was defined by the 2015 ATA guidelines.

RESULTS

Serum TSH concentrations gradually increased after lobectomy: proportions with TSH >2 mIU/L at post-lobectomy 1, 3-6, 12, and 24 months were found in 77.0%, 82.3%, 66.7%, and 59.9%, respectively. After lobectomy, 168 (45.5%) patients received levothyroxine (T4) supplementation. Multivariate logistic regression analyses showed that pre-TSH level >2 mIU/L was the sole independent variable predictive of the need for post-lobectomy TSH suppression (P = 0.003). During the median follow-up of 72 months, recurrence was found in 4 (1.1%) patients who never received T4 supplementation and had post-lobectomy TSH levels >2 mIU/L.

CONCLUSIONS

Our data show that thyroid lobectomy for unilateral PTC is associated with a low recurrence rate, but a significant risk of hypothyroidism. Preoperative TSH level can predict the need for post-lobectomy TSH suppression compliant with the 2015 ATA guidelines.

Radioactive Iodine for the Treatment of Subclinical Thyrotoxicosis Grade 1 and 2: Outcome of up to 18-Year Follow Up

BACKGROUND

Subclinical thyrotoxicosis (SCT) is associated with significant morbidity and mortality, specifically increased risk of atrial fibrillation and cardiovascular death. The management is ill-defined due to the scarcity of randomised controlled studies. Some clinicians recommend radioiodine (RAI) treatment however its long-term outcome is unknown. Therefore, further data is needed to provide robust evidence-based guidelines.

METHODS

A prospective, single-protocol analysis of the outcome of SCT patients (Grade 1; 0.1-0.4 mIU/L and Grade 2; <0.1 mIU/L) treated with mean dose of 427 MBq of I¹³¹, followed up for up to 18 years. Thyroid function tests were measured at 4-6 weeks, 3-, 6-, and 12-months post-RAI, and annually thereafter. Cure was defined as achieving a euthyroid/hypothyroid state.

RESULTS

Seventy-eight patients with a median age of 68 years (range 36-84) and varying aetiology [55 toxic multinodular goitre (TMNG), 10 toxic nodule (TN) and 13 Graves' disease (GD)] were followed up for a median period of 7.5 years (range 1-18). The cure rate was 100%. The rates of hypothyroidism in TMNG, TN and GD were 23.6%, 30% and 38.5% respectively. The median time to hypothyroidism was 6 and 12 months in GD and TMNG/TN respectively. No differences in outcome between Grade 1 versus Grade 2 were observed.

CONCLUSION

RAI using single mean dose of 427 MBq is effective and safe, irrespective of aetiology or grade of TSH suppression. GD patients become hypothyroid within the first year, whilst TMNG/TN for up to 9-years. Thus after 12 months of follow up, annual thyroid function monitoring is advised.

Transient high thyroid stimulating hormone and hypothyroidism incidence during follow up of subclinical hypothyroidism

Objectives. Given the high prevalence of subclinical hypothyroidism (SCH), defined as high thyroid stimulating hormone (TSH) and normal free thyroxine (FT4), and uncertainty on treatment, one of the major challenges in clinical practice is whether to initiate the treatment for SCH or to keep the patients under surveillance. There is no published study that has identified predictors of short-term changes in thyroid status amongst patients with mild elevation of TSH (4.5-10 mIU/L). Subjects and Results. A cohort study was conducted on patients with SCH detected through a general population screening program, who were followed for six months. This project identified factors predicting progression to hypothyroid status, persistent SCH and transient cases. A total of 656 participants joined the study (431 controls and 225 were patients with SCH). A part of participants (12.2%) developed biochemical hypothyroidism during the follow-up, while 73.8% of the subjects became euthyroid and the remained ones (13.4%) stayed in the SCH status. The incidence of overt hypothyroidism for participants with TSH above 6.9 mIU/L was 36.7%, with incidence of 42.3% for females. Anti-thyroid peroxidase antibodies (TPO) positivity is an important predictor of development of hypothyroidism; however, it could be also positive due to transient thyroiditis. Conclusions. It can be concluded that females with TSH above 6.9 mIU/L, particularly those with free triiodothyronine (FT3) and FT4 in the lower half of the reference range, are more likely to develop biochemical hypothyroidism. Therefore, it is recommended to give them a trial of levothyroxine replacement. It is also recommended to repeat TSH after six months for male subjects and participants with baseline TSH equal or less than 6.9 mIU/L.

Women with Subclinical Hypothyroidism are at Higher Prevalence of Metabolic Syndrome and Its Components Compared to Men in an Older Chinese Population

Purpose: This study investigated the impact of sex differences on the relationship of subclinical hypothyroidism (SCH) with the prevalence of metabolic syndrome (MetS) and its components in an older Chinese population.Methods: The study included 1842 older Chinese individuals aged 65 years or older who received annual health checkups. The impact of sex differences on the relationship of SCH with the prevalence of MetS and its components was investigated by multivariate logistic regression analysis. Interaction effect between sex and SCH on the prevalence of MetS and its components were evaluated using a multivariate logistic regression model which includes interaction terms (sex-SCH).Results: The study comprised 1701 (92.3%) individuals with euthyroidism and 141 (7.7%) with SCH. In men, SCH was not associated with MetS or any components of the MetS. In women, the SCH group had higher prevalence of MetS [odds ratio (OR), 1.870; 95% confidence interval (CI), 1.136-3.079], abdominal obesity (OR, 1.693; 95% CI, 1.043-2.748), hypertriglyceridemia (OR, 1.711; 95% CI, 1.054-2.775) and low high-density lipoprotein cholesterol (HDL-C) (OR, 3.039; 95% CI, 1.576-5.861). There was an interaction between sex and SCH in terms of the effect on the prevalence of MetS and its components, including abdominal obesity and hypertriglyceridemia (P < .01 for all), and with a trend for low HDL-C (P = .098).Conclusion: There were sex differences in the correlation of SCH with the prevalence of MetS and its components in the older Chinese population. An interaction effect between sex and SCH on the prevalence of MetS and its components was found.

Thyroid Hormone Plays an Important Role in Cardiac Function: From Bench to Bedside

Thyroid hormones (THs) are synthesized in the thyroid gland, and they circulate in the blood to regulate cells, tissues, and organs in the body. In particular, they exert several effects on the cardiovascular system. It is well known that THs raise the heart rate and cardiac contractility, improve the systolic and diastolic function of the heart, and decrease systemic vascular resistance. In the past 30 years, some researchers have studied the molecular pathways that mediate the role of TH in the cardiovascular system, to better understand its mechanisms of action. Two types of mechanisms, which are genomic and non-genomic pathways, underlie the effects of THs on cardiomyocytes. In this review, we summarize the current knowledge of the action of THs in the cardiac function, the clinical manifestation and parameters of their hemodynamics, and treatment principles for patients with hyperthyroid- or hypothyroid-associated heart disease. We also describe the cardiovascular drugs that induce thyroid dysfunction and explain the mechanism underlying the thyroid toxicity of amiodarone, which is considered the most effective antiarrhythmic agent. Finally, we discuss the recent reports on the involvement of thyroid hormones in the regulation of myocardial regeneration and metabolism in the adult heart.

Changes in Serum Thyroid Function Predict Cognitive Decline in the Very Old: Longitudinal Findings from the Newcastle 85+ Study

Background: Low serum thyrotropin (TSH) has been associated with an increased risk of cognitive impairment in observational studies of older individuals, but the mechanism underlying this is unclear. We investigated the association between changes in thyroid status and cognitive impairment in very old adults, using prospective data from the Newcastle 85+ study. Method: A cohort of 85-year-old individuals was assessed for health status and thyroid function. Complete data from a comprehensive multidimensional measure of health and repeat thyroid function were available for 642 participants with normal free thyroid hormones and TSH levels ranging between 0.1 and 10 mU/L. Cognitive performance, assessed using Mini-Mental State Examination (MMSE) and Cognitive Drug Research battery was examined by using linear mixed, logistic regression, and Cox proportional hazard models in relation to baseline and 3-year changes in serum TSH, free thyroxine (fT4), and free triiodothyronine (fT3). Results: Over 3 years, declining serum TSH was associated with reductions in fT4 and fT3, and an increased risk of incident cognitive impairment by 5 years (odds ratio1.77 [95% confidence interval: 1.19-2.61]; p = 0.004). A greater reduction in MMSE score was associated with larger TSH decline, at 3 (p = 0.001) and 5 years (p < 0.001), respectively. Steady fT4 concentrations were found in participants with rising TSH. Conclusions: In contrast to physiological expectation, in this group of 85-year-olds, a declining serum TSH was associated with reductions in free thyroid hormones over time. A decreasing serum TSH trajectory over time anticipated cognitive decline in later life. Declining TSH concentrations are a biomarker for cognitive impairment in later life.

Hypothyroidism and urinary incontinence: Prevalence and association in a Danish, female sample from the Lolland-Falster Health study

INTRODUCTION

We aimed to estimate the prevalence of urinary incontinence (UI) in women with hypothyroidism and subclinical hypothyroidism and to examine the association of hypothyroidism and UI.

METHODS

This cross-sectional study was based on the population-based Lolland-Falster Health Study (LOFUS), Denmark. Data comprising a questionnaire, physical examination, and blood samples were collected between 2016 and 2020. Multiple logistic regression was used to estimate odds ratios (OR) and control for possible confounders: age, body mass index, diabetes, smoking, and education.

RESULTS

Of 7,699 women included in the study, 7.9% had hypothyroidism, and 2.4% had subclinical hypothyroidism. The prevalence of any UI in women with hypothyroidism, subclinical hypothyroidism, and a control group (normal level of thyroid hormones) was 43.6%, 38.1%, and 39.3%, respectively. After controlling for confounders, no association between hypothyroidism and any UI (OR 1.01, 95% CI 0.85-1.20) or frequent UI (OR 1.05, 95% CI 0.84-1.32) were demonstrated. Additional, no association between subclinical hypothyroidism and any UI (OR 0.87, 95% CI 0.64-1.18) or frequent UI (OR 1.15, 95 CI 0.79-1.69) were demonstrated.

CONCLUSIONS

In our female sample, the prevalence of UI was high regardless of the thyroid status. No association between hypothyroidism and any or frequent UI was demonstrated. The prevalence of hypothyroidism was 7.9%.

Molecular Interactions between Dietary Lipids and Bone Tissue during Aging

Age-related bone disorders such as osteoporosis or osteoarthritis are a major public health problem due to the functional disability for millions of people worldwide. Furthermore, fractures are associated with a higher degree of morbidity and mortality in the long term, which generates greater financial and health costs. As the world population becomes older, the incidence of this type of disease increases and this effect seems notably greater in those countries that present a more westernized lifestyle. Thus, increased efforts are directed toward reducing risks that need to focus not only on the prevention of bone diseases, but also on the treatment of persons already afflicted. Evidence is accumulating that dietary lipids play an important role in bone health which results relevant to develop effective interventions for prevent bone diseases or alterations, especially in the elderly segment of the population. This review focuses on evidence about the effects of dietary lipids on bone health and describes possible mechanisms to explain how lipids act on bone metabolism during aging. Little work, however, has been accomplished in humans, so this is a challenge for future research.

Validity and Reliability of the Thai Version of the Thyroid-Related Patient-Reported Outcome-A Thyroid-specific Quality of Life Questionnaire

Introduction  The Thyroid-Related Patient-Reported Outcome (ThyPRO) is a new thyroid-specific quality of life patient-reported outcome measure for benign thyroid disorders.

Objective  The objective of this study was to investigate the face validity, internal consistency, and test-retest reliability of the Thai version of the ThyPRO (ThyPROth).

Methods  The translation of the ThyPRO questionnaire was performed using double forward translation, reconciliation, single backward translation, and cognitive debriefing, followed by a panel review. Five thyroid patients evaluated the face validity. The internal consistency and test-retest reliability were evaluated in 30 patients with thyroid diseases.

Results  The overall validity score was 3.75 (range 0–4). The Cronbach α coefficient ranged from 0.76 to 0.95, with a total coefficient of 0.97 (95% CI 0.962–0.959), indicating excellent internal consistency. The test-retest reliability coefficient ranged from 0.70 to 0.97. All values were 0.70 and above. The total reliability coefficient was 0.86 (95% CI 0.724–0.932), indicating excellent reliability.

Conclusion  The ThyPROth was found to be valid and to exhibit good internal consistency and test-retest reliability. The questionnaire is ready for implementation in the assessment of health-related quality of life in Thai patients with benign thyroid diseases.

Reference Intervals for Serum Thyroid-Stimulating Hormone Based on a Recent Nationwide Cross-Sectional Study and Meta-Analysis

OBJECTIVE

The aim of our study was to compare the reference intervals (RIs) [median (2.5^th-97.5^th percentiles)] for thyroid-stimulating hormone (TSH) between subgroups stratified by ethnicity and iodine status in a global context.

DESIGN AND METHODS

Primary data were derived from a recently published cross-sectional study in mainland China. Secondary data were obtained from online databases. The RIs for TSH were calculated in the reference population according to the National Academy of Clinical Biochemistry (NACB) standard and in the disease-free population. A meta-analysis of ethnicity- and iodine status-specific TSH RIs was performed.

RESULTS

The primary data showed that the TSH RI (mU/L) in the disease-free population was 2.33 (0.67, 7.87), which is wider than the published RI [2.28 (0.74, 7.04)] in the reference population. The meta-analysis showed that whether in the reference or disease-free population, the RIs in Yellows were much higher than those in Caucasians. In the reference population, the median and 2.5^th percentile in the iodine-sufficient subgroup were both lower than the iodine-deficient or more-than-adequate subgroup, while the 97.5^th percentile showed a positive trend with increasing sufficiency of iodine. However, in the disease-free population, the iodine-sufficient subgroup had a lower median and 97.5^th percentile but higher 2.5^th percentile than the iodine-deficient subgroup.

CONCLUSION

Yellows have a higher TSH RI than Caucasians. In the reference population, both the median and 2.5^th percentile TSH in the iodine-sufficient population were the lowest among the different iodine status subgroups, while the 97.5^th percentile of TSH showed an upward trend with increasing iodine sufficiency.

Subclinical Thyroid Dysfunction and the Risk of Cardiovascular Disease

The prevalence of subclinical hypothyroidism (SH) is 3-10%. The prevalence of subclinical hyperthyroidism (SHr) is 0.7-9.7%. Thyroid hormones affect cardiac electrophysiology, contractility, and vasculature. SH is associated with an increased risk of coronary heart disease (CHD), especially in subjects under 65. SHr seems to be associated with a slightly increased risk of CHD and an increase in CHD-related mortality. Both SH and SHr carry an increased risk of developing heart failure (HF), especially in those under 65. Both SH and SHr are associated with worse prognoses in patients with existing HF. SH is probably not associated with atrial fibrillation (AF). SHr, low normal thyroid-stimulating hormone (TSH) and high normal free thyroxine (FT4) are all associated with the increased risk of AF. An association between endothelial dysfunction and SH seems to exist. Data regarding the influence of SHr on the peripheral vascular system are conflicting. SH is a risk factor for stroke in subjects under 65. SHr does not increase the risk of stroke. Both SH and SHr have an unfavourable effect on cardiovascular disease (CVD) and all-cause mortality. There is a U-shaped curve of mortality in relation to TSH concentrations. A major factor that modifies the relation between subclinical thyroid disease (SCTD) and mortality is age. SH increases blood pressure (BP). SHr has no significant effect on BP. Lipids are increased in patients with SH. In SHr, high-density lipoprotein cholesterol and lipoprotein( a) are increased. SCTD should be treated when TSH is over 10 mU/l or under 0.1 mU/l. Treatment indications are less clear when TSH is between normal limits and 0.1 or 10 mU/L. The current state of knowledge supports the understanding of SCTD's role as a risk factor for CVD development. Age is a significant confounding factor, probably due to age-associated changes in the TSH reference levels.

Hypothyroidism impairs the host immune response during the acute phase of Chagas disease

Diseases associated with thyroid hypofunction have been the subject of studies in infectious models, since several authors have demonstrated a pivotal role of iodinated hormones (thyroxine and triiodothyronine) in the modulation of immune effector responses. Using a model of hypothyroidism induced by anti-thyroid drug, we investigated the influence of hypothyroidism in the course of acute Trypanosoma cruzi infection. For this, male Hannover Wistar rats were challenged with methimazole for 21 days (0.02% in drinking water), and water for control counterparts. After confirmation of the hypothyroidism, rats were intraperitoneally challenged with 1x10⁵ blood trypomastigotes of the Y strain of T. cruzi. Our findings suggest that hypothyroidism impairs animal weight gain, but does not affect the health of essential organs. Interestingly, infected hypothyroid animals had a significant increase in thymic cell death, with consequent drop in lymphocyte frequency in whole blood (evaluated on the 11th day of infection). Analyzing the percentage of immune cells in the spleen, we found a strong influence of hypothyroidism as a negative regulator of B cells, and antigenic ability of macrophages (RT1b expression) in the course of the experimental chagasic infection. Enhanced serum IL-17A concentration was induced by T. cruzi infection, but hypothyroidism impaired the production of this mediator as seen in infected hypothyroid animals. Taken together, our work suggests for the first time that hypothyroidism may adversely interfere with the modulation of effective immunity in the early phase of Chagas' disease.

The interplay between thyroid and liver: implications for clinical practice

A complex relationship exists between thyroid and liver in health and disease. Liver plays an essential physiological role in thyroid hormone activation and inactivation, transport, and metabolism. Conversely, thyroid hormones affect activities of hepatocytes and hepatic metabolism. Serum liver enzyme abnormalities observed in hypothyroidism may be related to impaired lipid metabolism, hepatic steatosis or hypothyroidism-induced myopathy. Severe hypothyroidism may have biochemical and clinical features, such as hyperammonemia and ascites, mimicking those of liver failure. Liver function tests are frequently abnormal also in hyperthyroidism, due to oxidative stress, cholestasis, or enhanced osteoblastic activity. Antithyroid drug-associated hepatotoxicity is a rare event, likely related mainly to an idiosyncratic mechanism, ranging from a mild hepatocellular damage to liver failure. Propylthiouracil-induced liver damage is usually more severe than that caused by methimazole. On the other hand, thyroid abnormalities can be found in liver diseases, such as chronic hepatitis C, liver cirrhosis, hepatocellular carcinoma, and cholangiocarcinoma. In particular, autoimmune thyroid diseases are frequently found in patients with hepatitis C virus infection. These patients, especially if thyroid autoimmunity preexists, are at risk of hypothyroidism or, less frequently, thyrotoxicosis, during and after treatment with interpheron-alpha alone or in combination with ribavirin, commonly used before the introduction of new antiviral drugs. The present review summarizes both liver abnormalities related to thyroid disorders and their treatment, and thyroid abnormalities related to liver diseases and their treatment.

Chinese Herbal Medicine Alleviates Thyroidectomy-Induced Cardiopulmonary Exercise Dysfunction in Rats

Hypothyroidism frequently causes cardiopulmonary dysfunction, such as heart failure and respiratory and metabolic deficiencies. This study investigated the effects of Chinese herbal formula B307 on thyroidectomy-induced cardiopulmonary exercise dysfunction in rats. Twenty male rats were equally divided into four groups: negative control with sham treatment, positive control with oral B307 treatment only, thyroidectomy treatment only, and thyroidectomy with B307 posttreatment groups. The feeding dose of B307 was 50 mg/kg per day for 14 days. We examined and then compared the thyroid-stimulating hormone (TSH), free triiodothyronine (T3), free thyroxine (T4), and reactive oxygen species (ROS) from the blood of these four groups. Also, we compared the body weight, neck subcutaneous blood flow, cardiac ejection function, cardiopulmonary exercise function of oxygen consumption (VO₂), carbon dioxide production (VCO₂), and respiratory quotient (RQ = VCO₂/VO₂) among the four groups. Our results indicated that thyroidectomized rats had significantly decreased body weight, neck subcutaneous blood flow, cardiac ejection function, serum T3 and T4, and VO₂ and VCO₂, but had significantly increased ROS and TSH levels and RQ values compared with sham rats (P < 0.01-0.05). In addition, thyroidectomized rats receiving oral B307 treatment had significantly increased body weight, neck subcutaneous blood flow, cardiac ejection function, and VO₂, but significantly decreased ROS and TSH levels and VCO₂ and RQ values compared with thyroidectomized rats (P < 0.01-0.05). We suggest that the B307 could be a protective and beneficial alternative treatment for thyroidectomy-induced cardiopulmonary exercise dysfunction.

TSH Levels in Subclinical Hypothyroidism in the 97.5th Percentile of the Population

The debate regarding the cutoff point in the treatment of patients with subclinical hypothyroidism (Shypo) is ongoing. Generally, two different groups are identified for treatment by levels of 10 and 20 mIU/L. Nevertheless, the question remains, "what cutoff point should be chosen?" We have written a selective nonsystematic review focused on the 97.5 percentile reference value reported in healthy subjects in a number of countries and observed important disparities, which partly show the challenge of identifying a single cutoff point for those patients needing medication. We identified studies of TSH on the natural history of subclinical hypothyroidism from population-based prospective cohort studies, which follow up patients for several years. The evolution of TSH levels in these patients is variable. Some cases of TSH may return to lower levels at different stages over the years, but others may not, possibly even developing into overt thyroid failure, also variable. We analyzed factors that may explain the normalization of serum TSH levels. In addition, we found that thorough population-based prospective cohort studies following up on TSH levels, thyroid antibodies, and ultrasonography are important in decisions made in the treatment of patients. However, the 97.5 percentile reference value varies in different countries; therefore, an international cutoff point for subclinical hypothyroidism cannot be recommended.

Hypothyroidism and Heart Failure: Epidemiology, Pathogenetic Mechanisms & Therapeutic Rationale

Heart Failure (HF) is a major public health problem and a major cause of morbidity and mortality worldwide. Thyroid hormones (TH) have multiple effects on the heart and cardiovascular system. In recent years, studies have shown that hypothyroidism, including subclinical hypothyroidism, is associated with an increased risk for developing and worsening of HF. This review addresses the relationship between HF and hypothyroidism by highlighting the epidemiology, pathophysiology and management.

The kidney, subclinical thyroid disease and cardiovascular outcomes in older patients

OBJECTIVE

Thyroid hormones have been implicated to play a role in cardiovascular disease, along with studies linking thyroid hormone to kidney function. The aim of this study is to investigate whether kidney function modifies the association of subclinical thyroid dysfunction and the risk of cardiovascular outcomes.

METHODS

In total, 5804 patients were included in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). For the current analysis, 426 were excluded because of overt thyroid disease at baseline or 6 months, 266 because of inconsistent thyroid function at baseline and 6 months, 294 because of medication use that could influence thyroid function, and 16 because of missing kidney or thyroid values. Participants with normal fT4 were classified, based on TSH both at inclusion and 6 months, into three groups: subclinical hypothyroidism (TSH >4.5 mIU/L); euthyroidism (TSH = 0.45-4.5 mIU/L); and subclinical hyperthyroidism (TSH <0.45 mIU/L). Strata of kidney function were made based on estimated glomerular filtration rate into three clinically relevant groups: <45, 45-60, and >60 mL/min/1.73 m2. The primary endpoint consists of death from coronary heart disease, non-fatal myocardial infarction and (non)fatal stroke.

RESULTS

Mean age was 75.3 years, and 49.0% patients were male. Mean follow-up was 3.2 years. Of all participants, 109 subjects (2.2%) had subclinical hypothyroidism, 4573 (94.0%) had euthyroidism, and 182 (3.7%) subclinical hyperthyroidism. For patients with subclinical hypothyroidism, euthyroidism, and subclinical hyperthyroidism, primary outcome occurred in 9 (8.3%), 712 (15.6%), and 23 (12.6%) patients, respectively. No statistically significant relationship was found between subclinical thyroid dysfunction and primary endpoint with adjusted hazard ratios of 0.51 (0.24-1.07) comparing subclinical hyperthyroidism and 0.90 (0.58-1.39) comparing subclinical hypothyroidism with euthyroidism. Neither was this relationship present in any of the strata of kidney function, nor did kidney function interact with subclinical thyroid dysfunction in the association with primary endpoint (P interaction = 0.602 for subclinical hyperthyroidism and 0.388 for subclinical hypothyroidism).

CONCLUSIONS

In this secondary analysis from PROSPER, we found no evidence that the potential association between thyroid hormones and cardiovascular disease is modified by kidney function in older patients with subclinical thyroid dysfunction.

Risk factors for hypothyroidism in euthyroid thyroid nodule patients with lymphocytic thyroiditis on fine needle aspiration cytology

BACKGROUND/AIMS

Lymphocytic thyroiditis as cytology diagnosis from fine needle aspiration (FNA) is frequently detected in patients with thyroid nodules. However, the clinical outcome for upcoming hypothyroid events has been rarely clarified in euthyroid patients.

METHODS

We retrospectively reviewed the data of patient who had lymphocytic thyroitidis on FNA cytology of thyroid nodule from January 2005 to December 2010 at a tertiary referral hospital. In total, 109 patients with follow-up thyroid function tests (TFT) were enrolled. Final outcomes included overt and subclinical hypothyroidism with thyroid stimulating hormone (TSH) levels ≥ 10 mIU/L. Potential parameters predicting clinical hypothyroidism were analyzed by multivariate analysis.

RESULTS

Over the mean follow-up duration of 51.6 months, 14 out of 109 patients (12.8%) developed clinical hypothyroidism that required thyroid hormone replacement. The median onset time to hypothyroidism was 16 months (range, 3 to 88) and ≥ 60% of patients experienced clinical hypothyroidism within 1 year. By multivariate analysis, background thyroiditis (relative risk [RR], 9.78; p = 0.004), thyroid peroxidase antibody positivity (RR, 9.90; p = 0.003), nodule size (RR, 1.24; p < 0.001), and initial TSH (RR, 1.47; p = 0.009) were the independent risk factors for predicting hypothyroidism in euthyroid patients.

CONCLUSION

Hypothyroidism frequently occurs during the follow-up in euthyroid patients with thyroid nodules which show lymphocytic thyroiditis on FNA cytology. Close surveillance and regular TFT are needed in high-risk patients for upcoming clinical hypothyroidism.

Thyroid disease in end-stage renal disease

PURPOSE OF REVIEW

Hypothyroidism is a highly prevalent endocrine disorder in the end-stage renal disease (ESRD) population, yet many cases may remain latent and undiagnosed.

RECENT FINDINGS

Epidemiologic data show that there is a nearly five-fold higher prevalence of hypothyroidism in advanced chronic kidney disease (CKD) patients vs. those without CKD. Given that the metabolism, degradation, and excretion of thyroid hormone and its metabolites, as well as the regulation of the hypothalamic-pituitary-thyroid axis may be altered in ESRD, certain considerations should be made when interpreting thyroid functional tests in these patients. Growing evidence shows that hypothyroidism and other thyroid functional test derangements are associated with higher risk of cardiovascular disease, worse patient-centered outcomes, and survival in the advanced CKD population, including those with ESRD. Although limited data examining treatment of hypothyroidism suggests benefit, further studies of the efficacy and safety of thyroid hormone supplementation, including clinical trials and rigorous longitudinal observational studies are needed to inform the management of thyroid dysfunction in CKD.

SUMMARY

Given the high burden of hypothyroidism in ESRD patients, and potential ill effects on their cardiovascular health, patient-centered outcomes, and survival, further research is needed to inform the optimal management of thyroid dysfunction in this population.

The prevalence and incidence of thyroid dysfunction in patients with diabetes - a longitudinal follow-up study

BACKGROUND

Thyroid dysfunction (TD) occurs in 13.4% of diabetic patients, which has prompted recommendations for annual thyroid screening in patients with diabetes. However, recommendations for annual screening should be based on disease incidence rather than prevalence.

METHODS

In 1997-1998, seven hundred and thirty patients (618 type 2 diabetes, 55% male; 112 type 1 diabetes, 47% male) were sequentially screened for TD. The 639 patients with normal thyroid function were followed from 1999 to 2006, with annual thyroid function tests.

RESULTS

A total of 21/112 (19%) with type 1 diabetes (T1DM) and 70/618 (11%) with type 2 diabetes (T2DM) had TD. TD was more frequent in females (p < 0.05) and T1DM (p = 0.04). The mean annual rate of conversion to abnormal tests was 2.1%. At 8 years, there were 100 new cases of TD representing 15.6% of the cohort (17 T1DM and 83 T2DM). TD was more frequent in females (p < 0.05), but there was no difference in the incidence of new TD between T1DM and T2DM (p = 0.39).

CONCLUSIONS

Our data confirms the high prevalence of TD in diabetic patients, in concordance with the results from other series. We found only 25 treatable cases of new thyroid disease from 639 patients in the 8-year follow-up, less than 0.5% per year. The low incidence of treatable thyroid disease challenges the need for annual screening for thyroid abnormalities in patients with type 2 diabetes.

Graves' disease, multinodular goiter and subclinical hyperthyroidism

Subclinical hyperthyroidism is a common clinical entity, defined by serum TSH below the reference range, with normal FT4 and FT3 levels in an asymptomatic patient. Whether or not subclinical hyperthyroidism should be treated remains a matter of debate. Cross-sectional and longitudinal population-based studies demonstrate association of subclinical hyperthyroidism with risk of atrial fibrillation and osteoporosis, and with cardiovascular and all-cause mortality. However, there are no randomized clinical trials addressing whether long-term health outcomes are improved by treating subclinical hyperthyroidism; in the absence of evidence one way or the other, it seems appropriate to use decision trees taking account of TSH concentration and presence of risk factors (age>65 years or post-menopause, osteoporosis and cardiac disease).

A Cross-Sectional Study to Assess the Prevalence of Adult Thyroid Dysfunction Disorders in Jordan

Background: Insufficient production of thyroid hormones results in hypothyroidism, while overproduction results in hyperthyroidism. These are common adult disorders, with hypothyroidism more common in the elderly. Jordan has had past problems with dietary iodine deficiency but there are no published studies assessing the population prevalence of these disorders in the Arab Middle East. Methods: A cross-sectional study was conducted in three representative areas of Jordan. There were 7085 participants with a mean age of 40.8 years. Participants completed a questionnaire and had blood taken for thyroid analysis. Results:Hypothyroidism: The prevalence of any hypothyroidism (already diagnosed and/or identified by blood testing) was 17.2% in females and 9.1% in males. Undiagnosed prevalence was 8% and 6.2% for females and males, respectively. The prevalence of subclinical hypothyroidism, defined as high serum thyrotropin (TSH) and normal serum-free thyroxine (fT4), was 5.98% among females and 4.40% among males. The prevalence of overt hypothyroidism, defined as high TSH and low fT4, was 2.00% among females and 1.80% among males. Only 53.5% (55.3% for females, 42.1% males) of those previously diagnosed with hypothyroidism had TSH levels within the appropriate range. Hyperthyroidism: The prevalence of any hyperthyroidism (already diagnosed and/or identified by blood testing) was 1.8% in females and 2.27% in males. The undiagnosed prevalence was 1.4% and 2.1% for females and males, respectively. The prevalence of subclinical hyperthyroidism (low TSH and normal fT4) was 1.20% and 1.80% among males and females accordingly. The prevalence of overt hyperthyroidism (low TSH and high fT4) was 0.2% among females and 0.3% among males. About 85.7% (83.3% for females, 100% males) of those previously diagnosed with hyperthyroidism had TSH levels within the appropriate range. Conclusions: The results of this study reveal that the total prevalence of thyroid dysfunction among adult females and males in Jordan is very high compared with international statistics, particularly in the rates of undiagnosed cases. This indicates the need for further assessment of the value of screening for adult hypothyroidism in Jordan.

Incidental findings on brain imaging and blood tests: results from the first phase of Insight 46, a prospective observational substudy of the 1946 British birth cohort

OBJECTIVE

To summarise the incidental findings detected on brain imaging and blood tests during the first wave of data collection for the Insight 46 study.

DESIGN

Prospective observational sub-study of a birth cohort.

SETTING

Single-day assessment at a research centre in London, UK.

PARTICIPANTS

502 individuals were recruited from the MRC National Survey of Health and Development (NSHD), the 1946 British birth cohort, based on pre-specified eligibility criteria; mean age was 70.7 (SD: 0.7) and 49% were female.

OUTCOME MEASURES

Data regarding the number and types of incidental findings were summarised as counts and percentages, and 95% confidence intervals were calculated.

RESULTS

93.8% of participants completed a brain scan (n=471); 4.5% of scanned participants had a pre-defined reportable abnormality on brain MRI (n=21); suspected vascular malformations and suspected intracranial mass lesions were present in 1.9% (n=9) and 1.5% (n=7) respectively; suspected cerebral aneurysms were the single most common vascular abnormality, affecting 1.1% of participants (n=5), and suspected meningiomas were the most common intracranial lesion, affecting 0.6% of participants (n=3); 34.6% of participants had at least one abnormality on clinical blood tests (n=169), but few reached the prespecified threshold for urgent action (n=11).

CONCLUSIONS

In older adults, aged 69-71 years, potentially serious brain MRI findings were detected in around 5% of participants, and clinical blood test abnormalities were present in around one third of participants. Knowledge of the expected prevalence of incidental findings in the general population at this age is useful in both research and clinical settings.

Risk factors for low plasma thyroxine and high plasma thyroid-stimulating hormone concentrations in dogs with non-thyroidal diseases

The aim of the current study was to identify independent risk factors for thyroid axis alterations in dogs with non-thyroidal diseases. In this retrospective cross-sectional study, data and plasma samples from 207 dogs with non-thyroidal diseases was used. The involvement of various factors (disease severity, sex, age, breed, category and duration of disease, and medication) in the alteration of plasma thyroxine (T4) or thyroid-stimulation hormone (TSH) concentrations was analyzed using multivariate logistic regression. Among the 207 dogs analyzed, 99 (47.8%) had low plasma T4 concentrations, while 45 (21.7%) had high TSH concentrations. Intact male sex [odds ratio (OR), 3.25; 1.67-6.35; P<0.001], Labrador Retrievers (OR, 18.70; 2.32-151.00; P=0.006), moderate (OR, 2.39; 1.21-4.74; P=0.012) and severe diseases (OR, 6.84; 2.27-20.70; P<0.001) were associated with increased risk for low plasma T4 concentrations. Meanwhile, intact male (OR, 3.93; 1.51-10.30; P=0.005), spayed female (OR, 4.22; 1.59-11.20; P=0.004), older age (OR, 2.73; 1.28-5.84; P=0.009), and Miniature Dachshunds (OR, 5.39; 2.38-12.20; P<0.001) had increased risk for high plasma TSH concentrations. Disease severity had been determined as an independent risk factor for canine NTIS. In addition, sex, age and breed were also associated with thyroid axis alterations in dogs with non-thyroidal diseases.

Annual Incidence of Thyroid Disease in Patients Who First Time Visit Department for Thyroid Diseases in Tuzla Canton

AIM

The aim of this paper was to evaluate the incidence of thyroid gland diseases in relation to age, sex, existing associated symptoms and thyroxine and thyroid-stimulating hormone levels, in correlation with morphological characteristics and corresponding clinical diagnosis for thyroid gland.

METHODS

Retrospective research was conducted in the period 1-Dec-2017 to 31-Dec-2017 and included a total of 500 subjects of both sexes aged 1 to 80 years. All subjects had clinical examination, which included anamnestic data, palpatory examination of thyroid gland, as well as functional status of thyroid gland.

RESULTS

The results of the research have shown that majority of subjects were females (78.6% vs. 21.4%). The largest number of subjects was in the age group 41 to 60 years. The average age of females was 43.22 years and 42.86 for males. The most common associated symptom for both sexes was related to cardiovascular system disorder (61.2%). Subclinical hypothyroidism was the most prevalent thyroid gland disease (12.8%), while diffuse enlargement of thyroid gland (4.60 %) was the most common in morphological classification. The mean value for free thyroxine for the overall sample was 14.39 pmol/L and 3,4 mlU/L for thyroid-stimulating hormone. Thyroid-stimulating hormone levels were highest in the age group 41-60 years (p=0.043).

CONCLUSION

The overall incidence of thyroid gland diseases was 18.57% for females and 13.08% for males. Free thyroxine levels were highest in thyroid gland with nodular changes and subclinical hypothyroidism (p=0.0001). Thyroid-stimulating hormone levels had the highest value in a thyroid gland with diffuse changes and subclinical hypothyroidism (p=0.0001).

Reference intervals in the diagnosis of thyroid dysfunction: treating patients not numbers

Although assigning a diagnosis of thyroid dysfunction appears quite simple, this is often not the case. Issues that make it unclear whether thyroid function is normal include transient changes in thyroid parameters, inter-individual and intra-individual differences in thyroid parameters, age-related differences, and ethnic variations. In addition, a statistically calculated distribution of thyroid analytes does not necessarily coincide with intervals or cutoffs that have predictive value for beneficial or adverse health outcomes. Based on current clincial trial data, it is unclear which individuals with mild thyroid-stimulating hormone elevations will benefit from levothyroxine treatment. For example, only a small number of patients with thyroid-stimulating hormone values of more than 10 mIU/L have been studied in a randomised manner. Even if therapy is initiated for abnormal thyroid function, not all treated individuals are maintained at the desired treatment target, and therefore might still be at risk. The consequence of this is that each patient's thyroid function needs to be assessed on an individual basis with the entire clinical picture in mind. Monitoring also needs to be vigilant, and the targets for treatment reassessed continually.

Thyronamine regulation of TAAR1 expression in breast cancer cells and investigation of its influence on viability and migration

Objectives

A correlation exists between breast cancer and thyroid disorders, which are common in elderly women. Thyroid hormones are degraded into trace amines, which can bind to the G-protein-coupled receptor trace amine-associated receptor 1 (TAAR1) and thereby activate it. The transformation of thyroid hormones into trace amines is carried out by the ornithine decarboxylase. Previously, we showed that TAAR1 overexpression (IRS ≥6) was associated with a significantly longer OS in primary breast cancer patients during a long-term follow-up of up to 14 years. Aim of the present study was to analyze the regulation of TAAR1 in breast cancer cell lines and the influence of triiodothyronine (T₃), thyronamines, and tetraiodothyroacetic acid (Tetrac) on the expression of TAAR1 in breast cancer cells.

Methods

The effect of T₃, thyronamines, and Tetrac on the expression of TAAR1 in breast cancer cell lines MCF-7 and T47D was analyzed via PCR and Western blot. A MTT assay was performed to test the metabolic cell viability. A scratch assay was performed to analyze cell migration.

Results

Stimulation of MCF-7 cells with 10 nM 3-iodothyronamine (T₁AM) significantly increased TAAR1 protein expression (P=0.008). In T47D cells, TAAR1 expression was significantly upregulated after the addition of 10 µg/mL estradiol to 10 nM T₁AM (P=0.008). A significant (P=0.028) reduction in MCF-7 cell viability through the incubation with T₁AM could be detected. Cell migration of MCF cells was significantly reduced through incubation with 10 nM T₁AM.

Conclusion

A significant upregulation of TAAR1 induced by stimulation with T₁AM may be a sign for an increased decarboxylation of thyroid hormones in breast cancer cells. In addition, there seems to be an influence of estradiol for the T₁AM-induced upregulation of TAAR1 in T47D cells. TAAR1-related cell transduction mechanisms seem to be an interesting target for endocrine treatment options of breast cancer patients.

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 in the Elderly: Who Should Be Treated and How?

Hypothyroidism is among the most frequent chronic diseases in the elderly, and levothyroxine (l-T4) is worldwide within the 10 drugs more prescribed in the general population. Hypothyroidism is defined by increased serum thyroid-stimulating hormone (TSH) values and reduced circulating free thyroid hormones, whereas subclinical hypothyroidism (sHT) is characterized by free hormone fractions within the normal ranges and has been divided into two classes, depending on circulating TSH levels (above or below 10 mIU/L). Given that during aging, a natural trend toward higher values of circulating TSH has been reported, it is necessary to verify carefully the diagnosis of sHT to tailor an appropriate follow-up and ad hoc therapy, avoiding unnecessary or excessive treatment. In the current review, we evaluate the state of the art on hypothyroidism in the elderly with special focus on the effect of sHT on cognition and the cardiovascular system function. We also summarize the recommendations for a correct diagnostic workup and therapeutic approach to older people with an elevated TSH value, with special attention to the presence of frailty, comorbidities, and poly therapy. In conclusion, personalized therapy is crucial in good clinical practice, and in the management of older patients with sHT, multiple factors must be considered, including age-dependent TSH cutoffs, thyroid autoimmunity, the burden of comorbidities, and the possible presence of frailty. l-T4 is the drug of choice for the treatment of hypothyroid older people, but the risk of overtreatment, potential adverse drug reactions, and patient compliance should always be considered and thyroid status periodically reassessed.

Graves' disease: Introduction, epidemiology, endogenous and environmental pathogenic factors

Graves' disease is the most frequent cause of hyperthyroidism. Many questions remain about the choice of diagnostic evaluations and treatment strategy according to clinical context (age, gender, pregnancy, etc.) and about the best management of the main extrathyroidal complication that is Graves orbitopathy. The exact pathogenic mechanisms are not fully clear. They associate genetic factors, interactions between endogenous and environmental factors, and immune system dysregulation. Graves' orbitopathy is one of the consequences of this partial understanding. Iatrogenic Graves' disease induced by the new targeted therapies are described and could help to better understand the molecular pathways involved in the disease and to develop new therapeutic approaches.

Stability of thyroid function in older adults: the Birmingham Elderly Thyroid Study

BACKGROUND

Thyroid function tests (TFTs) are among the most requested tests internationally. However, testing practice is inconsistent, and potentially suboptimal and overly costly. The natural history of thyroid function remains poorly understood.

AIM

To establish the stability of thyroid function over time, and identify predictors of development of overt thyroid dysfunction.

DESIGN AND SETTING

Longitudinal follow-up in 19 general practices in the UK.

METHOD

A total of 2936 participants from the Birmingham Elderly Thyroid Study (BETS 1) with a baseline TFT result indicating euthyroid or subclinical state were re-tested after approximately 5 years. Change in thyroid-stimulating hormone (TSH), free thyroxine (FT₄), and thyroid status between baseline and follow-up was determined. Predictors of progression to overt dysfunction were modelled.

RESULTS

Participants contributed 12 919 person-years; 17 cases of overt thyroid dysfunction were identified, 13 having been classified at baseline as euthyroid and four as having subclinical thyroid dysfunction. Individuals with subclinical results at baseline were 10- and 16-fold more likely to develop overt hypothyroidism and hyperthyroidism, respectively, compared with euthyroid individuals. TSH and FT₄ demonstrated significant stability over time, with 61% of participants having a repeat TSH concentration within 0.5 mIU/L of their original result. Predictors of overt hypothyroidism included new treatment with amiodarone (odds ratio [OR] 92.1), a new diagnosis of atrial fibrillation (OR 7.4), or renal disease (OR 4.8).

CONCLUSION

High stability of thyroid function demonstrated over the 5-year interval period should discourage repeat testing, especially when a euthyroid result is in the recent clinical record. Reduced repeat TFTs in older individuals is possible without conferring risk, and could result in significant cost savings.

Serum thyroid-stimulating hormone levels and smoking status: Data from the Korean National Health and Nutrition Examination Survey VI

OBJECTIVE

We aimed to evaluate differences in serum thyroid-stimulating hormone (TSH) levels according to smoking status and urine iodine concentration (UIC) in a healthy Korean population using data from the Sixth Korean National Health and Nutrition Examination Survey (KNHANES VI).

STUDY DESIGN

Sixth Korean National Health and Nutrition Examination Survey (2013-2015) is a nationwide, cross-sectional survey of the Korean population.

PATIENTS

Research subjects were selected by two-stage stratified cluster sampling of the population and housing census data. A total of 5639 subjects aged >18 years, who were not pregnant, and had undergone thyroid function testing during the survey period, were included.

MEASUREMENT

The level of serum TSH according to smoking status, iodine intake and presence of TPOAb were evaluated.

RESULTS

In the reference population, mean serum TSH level in current smokers (1.87 mIU/L, 95% CI, 0.52-5.37 mIU/L) was significantly lower than that in nonsmokers (2.33 mIU/L, 95% CI, 0.79-6.69 mIU/L, P < .001). The rate of thyroperoxidase antibody (TPOAb) positivity was higher in never smoker (7.7%) than past smokers (5.1%) and current smokers (4.7%), but sex-specific rate of TPOAb was not different according to smoking status. The lower serum TSH levels in current smokers were more apparent in iodine-deficient subjects (UIC < 100 μg/L), and this change was diminished in subjects with UICs between 100 and 299 μg/L. The difference in serum TSH levels in current smokers disappeared in subjects with UICs ≥ 300 μg/L.

CONCLUSIONS

Smoking is associated with a left-shift in serum TSH level that is more apparent in iodine-deficient subjects. Smoking status is not associated with the presence of TPOAb or iodine intake. The results suggest that smoking has a direct effect on thyroid function that is not mediated by autoimmune processes in the thyroid gland.