Associations between thyroid function and mortality: the influence of age

Effects of block-replace regimen in patients with autoimmune hypothyroidism converted to Graves' disease

PURPOSE

We present two cases of autoimmune hypothyroidism converted to Graves' disease (GD) and their medical management.

METHODS

We tested thyroid function and thyroid antibodies and performed an ophthalmologic examination and neck ultrasound in two patients with autoimmune hypothyroidism converted to GD during a follow-up of several years.

CASE REPORTS

The first case is a 33 year-old woman with hypothyroidism due to Hashimoto's thyroiditis (HT). She developed signs and symptoms of hyperthyroidism after 7 years of treatment with the same dose of levothyroxine (LT4). Even when LT4 therapy was discontinued, she remained thyrotoxic, with mild Graves' ophthalmopathy (GO) and very high thyroid-stimulating hormone receptor antibodies (TRAb > 40 IU/L, reference range: <1.75 IU/L). Antithyroid medication was started on a titration regimen, without achievement of euthyroidism. She was switched to a block and replace regimen, using 20 mg of methimazole (MMI) and 75 mcg of LT4 daily, with normalization of thyroid hormones and improvement of GO without steroids. The second case is a 57 year-old man with a 2-year positive medical history of HT and 6 months of LT4 treatment. He developed hyperthyroidism and moderate-severe GO. Despite stopping LT4 and initiating antithyroid medication in a titration regimen, he did not achieve euthyroidism and had active GO. Pulse glucocorticoid therapy and switching to a block-replace regimen was required to achieve euthyroidism and reduce ocular proptosis and diplopia.

CONCLUSION

Spontaneous autoimmune conversion of hypothyroidism to hyperthyroidism can occur at any time: it is important to promptly identify these cases so as to manage them effectively.

Trends in Prevalence of Thyroid Dysfunction and its Associations With Mortality Among US Participants, 1988-2012

CONTEXT

Various dynamic factors could influence the prevalence and distribution of thyroid dysfunction.

OBJECTIVE

To provide national estimates and temporal trends in prevalence of thyroid dysfunction over the past 3 decades in United States and determine the impact of thyroid dysfunction on mortality in US adults.

METHODS

A cross-sectional analysis of data from 33 117 participants aged 12 years or older in the National Health and Nutrition Examination Survey III (1988-1994), 1999-2002, and 2007-2012.

RESULTS

The weighted mean age was 41.6 years, and 48.3% were men. In 2007 through 2012, the prevalence of subclinical and overt hypothyroidism, subclinical and overt hyperthyroidism was 4.3%, 0.33%, 3.2%, and 0.2% respectively. Eighty percent of individuals with thyroid dysfunction were previously undiagnosed. The prevalence of subclinical hypothyroidism and hyperthyroidism was stable, whereas overt hypothyroidism (0.54% [95% CI, 0.35-0.8] vs 0.33% [95% CI, 0.23-0.48]) and hyperthyroidism (0.8% [95% CI, 0.58-1.1] vs 0.2% [95% CI, 0.12-0.33]) were less prevalent in 2007-2012 compared to 1988-1994. Older age, White Americans, obesity, and positivity for thyroid peroxidase antibody and thyroglobulin antibody were risk factors for hypothyroidism, whereas older age, women, and Black Americans were risk factors for hyperthyroidism. Over a median follow-up of 17.2 years, no significant association was observed between any type of thyroid dysfunction with the risk of total or cardiovascular mortality. However, among individuals aged 65 years or older, subclinical hypothyroidism was associated with a higher risk of total mortality (hazard ratio, 1.17; 95% CI, 1.00-1.37; P = .05) and cardiovascular mortality (HR, 1.29; 95% CI, 1.04-1.62; P = .02).

CONCLUSIONS

The prevalence of subclinical thyroid dysfunction remained relatively unchanged, whereas that of overt thyroid dysfunction decreased. Subclinical hypothyroidism was associated with a higher mortality among individuals aged 65 years or older.

The optimal healthy ranges of thyroid function defined by the risk of cardiovascular disease and mortality: systematic review and individual participant data meta-analysis

BACKGROUND

Reference intervals of thyroid-stimulating hormone (TSH) and free thyroxine (FT4) are statistically defined by the 2·5-97·5th percentiles, without accounting for potential risk of clinical outcomes. We aimed to define the optimal healthy ranges of TSH and FT4 based on the risk of cardiovascular disease and mortality.

METHODS

This systematic review and individual participant data (IPD) meta-analysis identified eligible prospective cohorts through the Thyroid Studies Collaboration, supplemented with a systematic search via Embase, MEDLINE (Ovid), Web of science, the Cochrane Central Register of Controlled Trials, and Google Scholar from Jan 1, 2011, to Feb 12, 2017 with an updated search to Oct 13, 2022 (cohorts found in the second search were not included in the IPD). We included cohorts that collected TSH or FT4, and cardiovascular outcomes or mortality for adults (aged ≥18 years). We excluded cohorts that included solely pregnant women, individuals with overt thyroid diseases, and individuals with cardiovascular disease. We contacted the study investigators of eligible cohorts to provide IPD on demographics, TSH, FT4, thyroid peroxidase antibodies, history of cardiovascular disease and risk factors, medication use, cardiovascular disease events, cardiovascular disease mortality, and all-cause mortality. The primary outcome was a composite outcome including cardiovascular disease events (coronary heart disease, stroke, and heart failure) and all-cause mortality. Secondary outcomes were the separate assessment of cardiovascular disease events, all-cause mortality, and cardiovascular disease mortality. We performed one-step (cohort-stratified Cox models) and two-step (random-effects models) meta-analyses adjusting for age, sex, smoking, systolic blood pressure, diabetes, and total cholesterol. The study was registered with PROSPERO, CRD42017057576.

FINDINGS

We identified 3935 studies, of which 53 cohorts fulfilled the inclusion criteria and 26 cohorts agreed to participate. We included IPD on 134 346 participants with a median age of 59 years (range 18-106) at baseline. There was a J-shaped association of FT4 with the composite outcome and secondary outcomes, with the 20th (median 13·5 pmol/L [IQR 11·2-13·9]) to 40th percentiles (median 14·8 pmol/L [12·3-15·0]) conveying the lowest risk. Compared with the 20-40th percentiles, the age-adjusted and sex-adjusted hazard ratio (HR) for FT4 in the 80-100th percentiles was 1·20 (95% CI 1·11-1·31) for the composite outcome, 1·34 (1·20-1·49) for all-cause mortality, 1·57 (1·31-1·89) for cardiovascular disease mortality, and 1·22 (1·11-1·33) for cardiovascular disease events. In individuals aged 70 years and older, the 10-year absolute risk of composite outcome increased over 5% for women with FT4 greater than the 85th percentile (median 17·6 pmol/L [IQR 15·0-18·3]), and men with FT4 greater than the 75th percentile (16·7 pmol/L [14·0-17·4]). Non-linear associations were identified for TSH, with the 60th (median 1·90 mIU/L [IQR 1·68-2·25]) to 80th percentiles (2·90 mIU/L [2·41-3·32]) associated with the lowest risk of cardiovascular disease and mortality. Compared with the 60-80th percentiles, the age-adjusted and sex-adjusted HR of TSH in the 0-20th percentiles was 1·07 (95% CI 1·02-1·12) for the composite outcome, 1·09 (1·05-1·14) for all-cause mortality, and 1·07 (0·99-1·16) for cardiovascular disease mortality.

INTERPRETATION

There was a J-shaped association of FT4 with cardiovascular disease and mortality. Low concentrations of TSH were associated with a higher risk of all-cause mortality and cardiovascular disease mortality. The 20-40th percentiles of FT4 and the 60-80th percentiles of TSH could represent the optimal healthy ranges of thyroid function based on the risk of cardiovascular disease and mortality, with more than 5% increase of 10-year composite risk identified for FT4 greater than the 85th percentile in women and men older than 70 years. We propose a feasible approach to establish the optimal healthy ranges of thyroid function, allowing for better identification of individuals with a higher risk of thyroid-related outcomes.

FUNDING

None.

Serum TSH and Daily Physical Activity in a Cohort of Nonagenarians: Results from the Mugello Study

BACKGROUND

The current literature does not furnish clear data concerning the relationship between thyroid function, sedentary time and daily physical activity (PA) in older adults with euthyroid condition. The aim of this study was to investigate the association of serum Thyrotropin-Stimulating Hormone (TSH), free Triiodothyronine (fT3) and free Thyroxine (fT4) with sedentary time and PA in a cohort of nonagenarians.

METHODS

A total of 108 nonagenarians (92.8 ± 3.2 years), participating in the Mugello Study, and with complete data on thyroid function, sedentary time, PA and sleeping (objectively collected through a multisensory device), were considered for the analysis.

RESULTS

Mainly, TSH negatively correlated with time spent lying down, and positively correlated with METs. fT4 levels were negatively associated with mean daily metabolic equivalents (METs) and with low-intensity PA practice (LIPAT), and positively associated with lying down and sleeping time. Similar results have been shown in the female sample. Mainly, participants with high-normal (third tertile) versus low-normal TSH (first tertile) had higher moderate-intensity PA (MIPAT) (p = 0.03). In the female sample, first TSH tertile had higher METs (p = 0.010), LIPAT (p = 0.02), MIPAT (p = 0.01) and lower time lying down (p = 0.04) than third TSH tertile.

CONCLUSION

High-normal serum TSH and low-normal fT4 are associated with higher levels and intensity of daily PA, together with higher MIPAT continuity, in the oldest-old.

Association of thyroid function, within the euthyroid range, with cardiovascular risk: The EPIPorto study

BACKGROUND

Thyroid hormones are important modulators of cardiovascular function. Both hypothyroidism and hyperthyroidism are known to contribute to an increased cardiovascular risk. It remains uncertain whether thyroid hormones level within the euthyroid range are associated with cardiometabolic risk. We aimed to evaluate the association between thyroid function levels within the euthyroid range and cardiovascular risk in a population-based cohort.

METHODS

Eight hundred thirty-five subjects aged ≥45 years from the EPIPorto population-based cohort were included. We excluded participants with TSH, free T4 (FT4), or free T3 (FT3) outside of the reference range, or with previous cardiovascular or thyroid disease. The associations between thyroid function, cardiovascular risk factors and the 10-year estimated risk of cardiovascular events (using SCORE2 and SCORE2-OP) were evaluated in linear and logistic regression models, crudely and adjusting for age, sex, BMI, diabetes, and smoking.

RESULTS

The mean age of the participants was 61.5 (SD 10.5) years and 38.9% were men. Eleven percent of the participants had diabetes, 47.8% had dyslipidemia, and 54.8% had hypertension. The mean body mass index (BMI) was 27.4 (SD 4.6) kg/m², and the median (percentile25-75) 10-year risk of cardiovascular events was 5.46% (2.92, 10.11). Participants with higher BMI, larger waist circumference and higher hs-CRP had higher levels of FT3 and FT3/FT4 ratio. Lower FT3/FT4 ratio and higher FT4 levels were associated with higher prevalence of diabetes and more adverse lipid profile. Higher TSH, lower FT3 and lower FT3/FT4 ratio were associated with lower eGFR. Lower FT3, lower FT3/FT4 ratio and higher FT4 were associated with an increased 10-year risk of cardiovascular events.

CONCLUSIONS

In a population-based study, variations of thyroid function within the euthyroid range were associated with cardiovascular risk factors. On one hand, individuals with higher BMI, larger waist circumference and higher hs-CRP had higher levels of FT3 and FT3/FT4 ratio. On the other hand, a decreased conversion of T4 to T3 (lower FT3, lower FT3/FT4 ratio and/or higher FT4) was associated with a higher prevalence of diabetes, a more adverse lipid profile, a lower eGFR and an increased 10-year risk of cardiovascular events.

OUP accepted manuscript

Background

The relationship between good early control of thyroid hormone levels after thyroidectomy for Graves’ disease (GD) and subsequent risks of mortality and morbidities is not well known. The aim of this study was to examine the association between thyroid hormone levels within a short interval after surgery and long-term mortality and morbidity risks from a population-based database.

Methods

Patients with GD who underwent complete/total thyroidectomy between 2006 and 2018 were selected from the Hong Kong Hospital Authority clinical management system. All patients were classified into three groups (euthyroidism, hypothyroidism, and hyperthyroidism) according to their thyroid hormone levels at 6, 12, and 24 months after surgery. Cox proportional hazards models were performed to compare the risks of all-cause mortality, cardiovascular disease (CVD), Graves’ ophthalmopathy, and cancer.

Results

Over a median follow-up of 68 months with 5709 person-years, 949 patients were included for analysis (euthyroidism, n = 540; hypothyroidism, n = 282; and hyperthyroidism, n = 127). The hypothyroidism group had an increased risk of CVD (HR = 4.20, 95 per cent c.i. 2.37 to 7.44, P < 0.001) and the hyperthyroidism group had an increased risk of cancer (HR = 2.14, 95 per cent c.i. 1.55 to 2.97, P < 0.001) compared with the euthyroidism group. Compared with patients obtaining euthyroidism both at 6 months and 12 months, the risk of cancer increased in patients who achieved euthyroidism at 6 months but had an abnormal thyroid status at 12 months (HR = 2.33, 95 per cent c.i. 1.51 to 3.61, P < 0.001) and in those who had abnormal thyroid status at 6 months but achieved euthyroidism at 12 months (HR = 2.52, 95 per cent c.i. 1.60 to 3.97, P < 0.001).

Conclusions

This study showed a higher risk of CVD in postsurgical hypothyroidism and a higher risk of cancer in hyperthyroidism compared with achieving euthyroidism early after thyroidectomy. Patients who were euthyroid at 6 months and 12 months had better outcomes than those achieving euthyroidism only at 6 months or 12 months. Attaining biochemical euthyroidism early after thyroidectomy should become a priority.

Determinants and Clinical Implications of Thyroid Peroxidase Antibodies in Middle-Aged and Elderly Individuals: The Rotterdam Study

Background: Thyroid peroxidase antibodies (TPO-Abs) play an important role in autoimmune thyroid disease, but are also prevalent in healthy individuals. However, it is unclear what determinants may influence the occurrence of TPO-Abs in healthy individuals and how TPO-Abs may affect health outcomes in these individuals. We aimed to identify determinants of TPO-Abs in a large, prospective population-based cohort of middle-aged and elderly individuals and to subsequently assess the association between TPO-Abs and risk of overall and cause-specific mortality. Methods: We performed binomial and multinomial logistic regression analyses to obtain odds ratios (ORs) and 95% confidence intervals [95% CIs] for the association of potential determinants based on previous literature with TPO-Ab positivity (>35 kU/L), TPO-Ab detectability (>5 kU/L), and TPO-Ab categories. Cox proportional hazards regression analyses were performed to obtain hazard ratios (HRs) and CIs for the association between TPO-Abs and mortality risk. Results: In 9685 participants (57% women, median baseline age 63.3 years, median follow-up time 10.1 years), we identified female sex (OR = 2.47 [CI 2.13-2.86]) and current smoking (OR = 3.10 [CI 2.66-3.62]) as determinants of TPO-Ab positivity and TPO-Ab detectability, respectively. Higher age (OR = 0.98 [CI 0.97-0.98]) and all categories of alcohol consumption (ORs ranging from 0.71-0.78) were associated with lower odds of TPO-Ab detectability. TPO-Ab detectability was associated with a higher risk of overall (HR = 1.09 [CI 1.01-1.17]), cancer-related (HR = 1.18 [CI 1.01-1.38]), and cardiovascular mortality (HR = 1.21 [CI 1.01-1.45]). Interestingly, this was more prominent in men compared with women (HR for cardiovascular mortality 1.50 vs. 0.99, respectively). Conclusions: In community-dwelling middle-aged and elderly individuals, female sex and current smoking are the most important determinants associated with TPO-Ab levels in the detectable and positive range, whereas alcohol consumption is associated with lower odds of TPO-Abs. The clinical importance of detectable TPO-Ab levels is illustrated by the association with an increased mortality risk, mainly in men. Our results warrant further exploration of the clinical applicability of detectable TPO-Ab levels, potentially as a marker for low-grade inflammation. The Rotterdam Study has been entered into the Netherlands National Trial Register (NTR; www.trialregister.nl) and into the WHO International Clinical Trials Registry Platform (ICTRP; www.who.int/ictrp/network/primary/en/) under shared catalogue number NTR6831.

Clinical Parameters Are More Likely to Be Associated with Thyroid Hormone Levels than with Thyrotropin Levels: A Systematic Review and Meta-Analysis

Background: Though the functional states of other endocrine systems are not defined on the basis of levels of controlling hormones, the assessment of thyroid function is based on levels of the controlling hormone thyrotropin (TSH). We, therefore, addressed the question as to whether levels of thyroid hormones [free thyroxine (fT4), total triiodothyronine (TT3)/free triiodothyronine (fT3)], or TSH levels, within and beyond the reference ranges, provide the better guide to the range of clinical parameters associated with thyroid status. Methods: A PubMed/MEDLINE search of studies up to October 2019, examining associations of levels of thyroid hormones and TSH, taken simultaneously in the same individuals, with clinical parameters was performed. We analyzed atrial fibrillation, other cardiac parameters, osteoporosis and fracture, cancer, dementia, frailty, mortality, features of the metabolic syndrome, and pregnancy outcomes. Studies were assessed for quality by using a modified Newcastle-Ottawa score. Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed. A meta-analysis of the associations was performed to determine the relative likelihood of fT4, TT3/fT3, and TSH levels that are associated with the clinical parameters. Results: We identified 58 suitable articles and a total of 1880 associations. In general, clinical parameters were associated with thyroid hormone levels significantly more often than with TSH levels-the converse was not true for any of the clinical parameters. In the 1880 considered associations, fT4 levels were significantly associated with clinical parameters in 50% of analyses. The respective frequencies for TT3/fT3 and TSH levels were 53% and 23% (p < 0.0001 for both fT4 and TT3/fT3 vs. TSH). The fT4 and TT3/fT3 levels were comparably associated with clinical parameters (p = 0.71). More sophisticated statistical analyses, however, indicated that the associations with TT3/fT3 were not as robust as the associations with fT4. Conclusions: Thyroid hormones levels, and in particular fT4 levels, seem to have stronger associations with clinical parameters than do TSH levels. Associations of clinical parameters with TSH levels can be explained by the strong negative population correlation between thyroid hormones and TSH. Clinical and research components of thyroidology currently based on the measurement of the thyroid state by reference to TSH levels warrant reconsideration.

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.

Association of Hypothyroidism and Mortality in the Elderly Population: A Systematic Review and Meta-Analysis

CONTEXT

The evidence of whether hypothyroidism increases mortality in the elderly population is currently inconsistent and conflicting.

OBJECTIVE

The objective of this meta-analysis is to determine the impact of hypothyroidism on mortality in the elderly population.

DATA SOURCES

PubMed, Embase, Cochrane Library, Scopus, and Web of Science databases were searched from inception until May 10, 2019.

STUDY SELECTION

Studies evaluating the association between hypothyroidism and all-cause and/or cardiovascular mortality in the elderly population (ages ≥ 60 years) were eligible.

DATA EXTRACTION

Two reviewers independently extracted data and assessed the quality of the studies. Relative risk (RR) was retrieved for synthesis. A random-effects model for meta-analyses was used.

DATA SYNTHESIS

A total of 27 cohort studies with 1 114 638 participants met the inclusion criteria. Overall, patients with hypothyroidism experienced a higher risk of all-cause mortality than those with euthyroidism (pooled RR = 1.26, 95% CI: 1.15-1.37); meanwhile, no significant difference in cardiovascular mortality was found between patients with hypothyroidism and those with euthyroidism (pooled RR = 1.10, 95% CI: 0.84-1.43). Subgroup analyses revealed that overt hypothyroidism (pooled RR = 1.10, 95% CI: 1.01-1.20) rather than subclinical hypothyroidism (pooled RR = 1.14, 95% CI: 0.92-1.41) was associated with increased all-cause mortality. The heterogeneity primarily originated from different study designs (prospective and retrospective) and geographic locations (Europe, North America, Asia, and Oceania).

CONCLUSIONS

Based on the current evidence, hypothyroidism is significantly associated with increased all-cause mortality instead of cardiovascular mortality among the elderly. We observed considerable heterogeneity, so caution is needed when interpreting the results. Further prospective, large-scale, high-quality studies are warranted to confirm these findings.

Cigarette smoking is associated with higher thyroid hormone and lower TSH levels: the PREVEND study

PURPOSE

The extent to which smoking is associated with thyroid stimulating hormone (TSH), free thyroxine (FT4), and free triiodothyronine (FT3) when taking account of clinical variables including alcohol consumption is unclear. We aimed to determine associations of TSH, FT4, and FT3 levels with current smoking.

METHODS

A cross-sectional study was performed in 5766 euthyroid participants (Prevention of Renal and Vascular End-Stage Disease cohort). Current smoking was determined by self-report, categorized as never, former, and current (≤20 and >20 cigarettes per day). Smoke exposure was determined by urinary cotinine.

RESULTS

Current smoking of ≤20 and >20 cigarettes per day was associated with lower TSH and higher FT3 levels. FT4 levels were higher in subjects smoking <20 cigarettes per day vs. never and former smokers. Current smokers also consumed more alcohol. Multivariable linear regression analyses adjusted for age, sex, anti-TPO autoantibody positivity, alcohol consumption, and other variables demonstrated that lower TSH, higher FT4 and higher FT3 were associated with smoking ≤20 cigarettes per day vs. subjects who never smoked (P < 0.001, P = 0.018, and P < 0.001, respectively) without a further significant incremental effect of smoking >20 cigarettes per day. In agreement, TSH was inversely, whereas FT4 and FT3 levels were positively associated with urinary cotinine (P < 0.001 for each). In contrast, alcohol consumption >30 g per day conferred higher TSH and lower FT3 levels.

CONCLUSIONS

Cigarette smoking is associated with modestly higher FT4 and FT3, and lower TSH levels, partly opposing effects of alcohol consumption.

High-normal thyroid-stimulating hormone in euthyroid subjects is associated with risk of mortality and composite disease endpoint only in women

INTRODUCTION

The aim of the study was to evaluate whether serum thyroid-stimulating hormone (TSH) within the normal range in euthyroid subjects (having normal free triiodothyronine (fT3) and thyroxine (fT4)) is related to the risk of overall mortality or a composite endpoint of death and nonfatal events.

MATERIAL AND METHODS

In 614 middle-aged adult hospital screenees, free of uncontrolled diabetes at baseline, the association of sex-specific TSH tertiles with death was prospectively assessed using Cox regression, with the composite endpoint assessed using logistic regression in adjusted analyses, stratified by gender.

RESULTS

In total, 64 deaths and additional incident nonfatal events in 141 cases were recorded at a mean 7.55 years' follow-up. Multivariable linear regression revealed TSH to be significantly associated among men with age (p = 0.006), but in women inversely with fT3 and fT4 (p < 0.001, and p = 0.024 respectively). In logistic regression analysis, adjusted for age, fT3, fT4, systolic blood pressure and serum total cholesterol, sex-specific baseline TSH tertiles were associated in men neither with the risk of death nor with composite endpoint. In contrast, in women, the highest compared with the bottom TSH tertile predicted the risk of composite endpoint (relative risk: 2.02, 95% CI: 1.07-3.82) and, much more strongly, the mortality risk, independently of fT4 increments.

CONCLUSIONS

The significant association of higher range of normal serum TSH in euthyroid middle-aged adults with the risk of death and nonfatal adverse outcomes in women alone cannot be accounted for by the action of thyroid hormone and is consistent with involvement of TSH in the pro-inflammatory state.

Subclinical Hypothyroidism and the Risk of Cardiovascular Disease and All-Cause Mortality: A Meta-Analysis of Prospective Cohort Studies

OBJECTIVES

To determine the impact of subclinical hypothyroidism (SCH) on the risk of cardiovascular disease (CVD) and all-cause mortality, a comprehensive meta-analysis was performed according to the age or coexisting CVD risk status of the participants.

METHODS

Studies regarding the association of SCH with all-cause mortality from PubMed and Embase databases were included. The pooled relative risk (RR) of CVD and all-cause mortality was calculated using the Mantel-Haenszel method. A subgroup analysis of participants with high CVD risk was conducted, including history of coronary, cerebral, or peripheral artery disease; dilated cardiomyopathy; heart failure; atrial fibrillation; venous thromboembolism; diabetes mellitus; or chronic kidney disease.

RESULTS

In total, 35 eligible articles incorporating 555,530 participants were included. SCH was modestly associated with CVD and all-cause mortality (RR for CVD = 1.33 [confidence interval (CI) 1.14-1.54]; RR for all-cause mortality = 1.20 [CI 1.07-1.34]). However, the association was not observed in participants aged ≥65 years. Subgroup analysis showed that participants with SCH and high CVD risk showed a significantly higher risk of all-cause mortality (RR for CVD = 2.20 [CI 1.28-3.77]; RR for all-cause mortality = 1.66 [CI 1.41-1.94]), whereas those with SCH and low CVD risk did not. Additional subgroup analysis of six studies with a mean participant age of ≥65 years and high CVD risk showed a significant high risk of all-cause mortality in the SCH group (RR = 1.41 [CI 1.08-1.85]; I² = 0%).

CONCLUSIONS

SCH is associated with an increased CVD risk and all-cause mortality, particularly in participants with high CVD risk.

2016 American Thyroid Association Guidelines for Diagnosis and Management of Hyperthyroidism and Other Causes of Thyrotoxicosis

BACKGROUND

Thyrotoxicosis has multiple etiologies, manifestations, and potential therapies. Appropriate treatment requires an accurate diagnosis and is influenced by coexisting medical conditions and patient preference. This document describes evidence-based clinical guidelines for the management of thyrotoxicosis that would be useful to generalist and subspecialty physicians and others providing care for patients with this condition.

METHODS

The American Thyroid Association (ATA) previously cosponsored guidelines for the management of thyrotoxicosis that were published in 2011. Considerable new literature has been published since then, and the ATA felt updated evidence-based guidelines were needed. The association assembled a task force of expert clinicians who authored this report. They examined relevant literature using a systematic PubMed search supplemented with additional published materials. An evidence-based medicine approach that incorporated the knowledge and experience of the panel was used to update the 2011 text and recommendations. The strength of the recommendations and the quality of evidence supporting them were rated according to the approach recommended by the Grading of Recommendations, Assessment, Development, and Evaluation Group.

RESULTS

Clinical topics addressed include the initial evaluation and management of thyrotoxicosis; management of Graves' hyperthyroidism using radioactive iodine, antithyroid drugs, or surgery; management of toxic multinodular goiter or toxic adenoma using radioactive iodine or surgery; Graves' disease in children, adolescents, or pregnant patients; subclinical hyperthyroidism; hyperthyroidism in patients with Graves' orbitopathy; and management of other miscellaneous causes of thyrotoxicosis. New paradigms since publication of the 2011 guidelines are presented for the evaluation of the etiology of thyrotoxicosis, the management of Graves' hyperthyroidism with antithyroid drugs, the management of pregnant hyperthyroid patients, and the preparation of patients for thyroid surgery. The sections on less common causes of thyrotoxicosis have been expanded.

CONCLUSIONS

One hundred twenty-four evidence-based recommendations were developed to aid in the care of patients with thyrotoxicosis and to share what the task force believes is current, rational, and optimal medical practice.

An Overview of the Thyroid Gland and Thyroid-Related Deaths for the Forensic Pathologist

The thyroid gland is a butterfly-shaped organ situated in the anterior neck whose functions have system-wide effects. Thyroid diseases represent some of the most commonly encountered endocrine disorders and therefore are commonly encountered at the time of autopsy. Knowing how the gland functions and the effects it may have on vital organs is important when determining the cause of death and significant contributory conditions. Endocrine-related deaths may be anatomically subtle, therefore histologic examination, review of medical records, and selected postmortem testing must be performed to correctly identify and document their presence. For this reason, it is recommended that pathologists consider regularly examining the thyroid gland histologically, particularly on decedents where no apparent anatomic cause of death is identified after the autopsy. This article provides an in-depth review of the thyroid gland, thyroid hormones, and thyroid diseases, including potential thyroid-related deaths and incidental autopsy findings.

Subclinical Thyroid Disease and Mortality in the Elderly: A Retrospective Cohort Study

OBJECTIVE

The association between subclinical hypothyroidism and hyperthyroidism and mortality in the elderly is poorly defined. This study was designed to evaluate the association between subclinical hypothyroidism and subclinical hyperthyroidism and mortality in the elderly and to define the thyroid-stimulating hormone values associated with excess mortality in the elderly.

METHODS

We performed a retrospective cohort study with a review of a computerized database of a large health care organization. Patients aged more than 65 years evaluated in the years 2002 to 2012 with documented normal free T4 values were included in the analysis. All cases of known thyroid disease or cases in which thyroid medications were dispensed were excluded. Analysis was performed only on individuals who were not treated for hyperthyroidism or hypothyroidism during the follow-up period. Subjects were divided into 3 groups based on thyroid-stimulating hormone values: normal (normal thyroid-stimulating hormone), subclinical hypothyroidism (thyroid-stimulating hormone >4.2 mIU/L), and subclinical hyperthyroidism (thyroid-stimulating hormone <0.35 mIU/L). All-cause mortality hazard ratio (HR) was compared among the 3 groups, and a subanalysis according to thyroid-stimulating hormone values was performed in those with subclinical hypothyroidism and subclinical hyperthyroidism.

RESULTS

A final analysis was performed on 17,440 individuals with subclinical thyroid disease (538 with subclinical hyperthyroidism [3.1%], 1956 with subclinical hypothyroidism [11.2%], 14,946 normal cases [85.7%], average age of 83 years, 10,289 were women) who were followed up for 10 years. Both subclinical hypothyroidism (HR, 1.75; confidence interval [CI], 1.63-1.88) and subclinical hyperthyroidism (HR, 2.33; CI, 2.08-2.63) were associated with significantly increased mortality, and this association persisted on multivariate analysis (subclinical hypothyroidism HR, 1.68; CI, 1.56-1.8, subclinical hyperthyroidism HR, 1.93; CI, 1.7-2.17). Crude mortality was elevated at 1, 2, and 5 years, but this association seemed to decrease as time from initial analysis increased (most significant association at 1 year). Thyroid-stimulating hormone values greater than 6.38 mIU/L were associated with the highest mortality in those with subclinical hypothyroidism after multivariate adjustment (HR, 1.708; CI, 1.38-2.12), whereas in subclinical hyperthyroidism, no threshold for increased mortality was identified. Mortality was higher.

CONCLUSIONS

Both subclinical hypothyroidism and subclinical hyperthyroidism are associated with increased mortality in the elderly. A threshold thyroid-stimulating hormone value (>6.35 mIU/L) exists for increased mortality in subclinical hypothyroidism, but not in subclinical hyperthyroidism.

The 2015 European Thyroid Association Guidelines on Diagnosis and Treatment of Endogenous Subclinical Hyperthyroidism

Endogenous subclinical hyperthyroidism (SHyper) is caused by Graves' disease, autonomously functioning thyroid nodules and multinodular goitre. Its diagnosis is based on a persistently subnormal serum thyroid-stimulating hormone (TSH) level with free thyroid hormone levels within their respective reference intervals. In 2014 the European Thyroid Association Executive Committee, given the controversies regarding the treatment of Endo SHyper, formed a task force to develop clinical practice guidelines based on the principles of evidence-based medicine. The task force recognized that recent meta-analyses, including those based on large prospective cohort studies, indicate that SHyper is associated with increased risk of coronary heart disease mortality, incident atrial fibrillation, heart failure, fractures and excess mortality in patients with serum TSH levels <0.1 mIU/l (grade 2 SHyper). Therefore, despite the absence of randomized prospective trials, there is evidence that treatment is indicated in patients older than 65 years with grade 2 SHyper to potentially avoid these serious cardiovascular events, fractures and the risk of progression to overt hyperthyroidism. Treatment could be considered in patients older than 65 years with TSH levels 0.1-0.39 mIU/l (grade 1 SHyper) because of their increased risk of atrial fibrillation, and might also be reasonable in younger (<65 years) symptomatic patients with grade 2 SHyper because of the risk of progression, especially in the presence of symptoms and/or underlying risk factors or co-morbidity. Finally, the task force concluded that there are no data to support treating SHyper in younger asymptomatic patients with grade 1 SHyper. These patients should be followed without treatment due to the low risk of progression to overt hyperthyroidism and the weaker evidence for adverse health outcomes.