Subclinical thyroid dysfunction and mortality: an estimate of relative and absolute excess all-cause mortality based on time-to-event data from cohort studies

Artificial intelligence-enabled electrocardiography contributes to hyperthyroidism detection and outcome prediction

BACKGROUND

Hyperthyroidism is frequently under-recognized and leads to heart failure and mortality. Timely identification of high-risk patients is a prerequisite to effective antithyroid therapy. Since the heart is very sensitive to hyperthyroidism and its electrical signature can be demonstrated by electrocardiography, we developed an artificial intelligence model to detect hyperthyroidism by electrocardiography and examined its potential for outcome prediction.

METHODS

The deep learning model was trained using a large dataset of 47,245 electrocardiograms from 33,246 patients at an academic medical center. Patients were included if electrocardiograms and measurements of serum thyroid-stimulating hormone were available that had been obtained within a three day period. Serum thyroid-stimulating hormone and free thyroxine were used to define overt and subclinical hyperthyroidism. We tested the model internally using 14,420 patients and externally using two additional test sets comprising 11,498 and 596 patients, respectively.

RESULTS

The performance of the deep learning model achieves areas under the receiver operating characteristic curves (AUCs) of 0.725-0.761 for hyperthyroidism detection, AUCs of 0.867-0.876 for overt hyperthyroidism, and AUC of 0.631-0.701 for subclinical hyperthyroidism, superior to a traditional features-based machine learning model. Patients identified as hyperthyroidism-positive by the deep learning model have a significantly higher risk (1.97-2.94 fold) of all-cause mortality and new-onset heart failure compared to hyperthyroidism-negative patients. This cardiovascular disease stratification is particularly pronounced in subclinical hyperthyroidism, surpassing that observed in overt hyperthyroidism.

CONCLUSIONS

An innovative algorithm effectively identifies overt and subclinical hyperthyroidism and contributes to cardiovascular risk assessment.

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.

Management of thyroid dysfunction and thyroid nodules in the ageing patient

Thyroid dysfunction is a common endocrine disorder in the general population, with a reported prevalence of 10-15%. However, this rate is even higher in older adults, with an estimated prevalence of ≈25% in some populations. Since elderly patients usually present more comorbidities than younger individuals, thyroid dysfunction may carry a synergistic negative health impact, mainly due to increased cardiovascular disease risk. Moreover, thyroid dysfunction in the elderly can be more difficult to diagnose due to its subtle or even asymptomatic clinical presentation, and the interpretation of thyroid function tests may be affected by drugs that interfere with thyroid function or by the coexistence of several diseases. On the other hand, thyroid nodules are also a prevalent condition in older adults, and its incidence increases with age. The assessment and management of thyroid nodules in the ageing patient should take into account several factors, as risk stratification, thyroid cancer biology, patient´s overall health, comorbidities, treatment preferences, and goals of care. In this review article, we summarize the current knowledge on the pathophysiology, diagnosis, and therapeutic management of thyroid dysfunction in elderly patients and we also review how to identify and manage thyroid nodules in this population.

Thyroid functional and molecular imaging

Radioiodine uptake (RAIU) test with iodine-123 (Na[¹²³I]I) or iodine-131 (Na[¹³¹I]I) enables accurate evaluation and quantification of iodine uptake and kinetics within thyroid cells. Thyroid Scintigraphy (TS) employing Na[¹²³I]I or ^99mTc-pertechnetate (Na[^99mTc]TcO₄) provides information regarding the function and topographical distribution of thyroid cells activity, including detection and localization of ectopic thyroid tissue. Destructive thyrotoxicosis is characterized by low RAIU with scintigraphically reduced radiotracer activity in the thyroid tissue, while productive thyrotoxicosis (i.e. hyperthyroidism "stricto sensu") is characterized by high RAIU with scintigraphically diffuse (i.e. Graves' Disease, GD and diffuse thyroid autonomy) or focal (i.e. autonomously functioning thyroid nodules, AFTN) overactivity. Accordingly, RAIU and/or TS are widely used to differentiate different causes of thyrotoxicosis. In addition, several radiopharmaceuticals are also available to help differentiate benign from malignant thyroid nodules and inform clinical decision-making: scintigraphic identification of AFTNs obviate fine-needle aspiration (FNA) biopsy, and [^99mTc]Tc-hexakis-(2‑methoxy-2-isobutyl isonitrile ([^99mTc]Tc-MIBI) and/or ¹⁸F-fluoro-d-glucose ([¹⁸F]FDG) may complement the work-up of cytologically indeterminate "cold" nodules for reducing the need for diagnostic lobectomies/thyroidectomies. Finally, RAIU studies are also useful for calculating the administered therapeutic activity of Na[¹³¹I]I to treat hyperthyroidism and euthyroid multinodular goiter. All considered, thyroid molecular imaging allows functional characterization of different thyroid diseases, even before clinical symptoms become manifest, and remains integral to the management of such conditions. Our present paper summarizes basic concepts, clinical applications, and potential developments of thyroid molecular imaging in patients affected by thyrotoxicosis and thyroid nodules.

Subclinical Thyrotoxicosis and Cardiovascular Risk: Assessment of Circulating Endothelial Progenitor Cells, Proangiogenic Cells, and Endothelial Function

BACKGROUND

Subclinical thyrotoxicosis (SCT) is defined by low or undetectable thyroid-stimulating hormones and normal thyroid hormones. The treatment of SCT is uncertain despite being associated with increased cardiovascular risk (CVR) and mortality. Circulating endothelial progenitor cells (cEPCs) and circulating angiogenic cells (CACs) have been found to be reduced in conditions with CVR. We aimed to evaluate whether endothelial function and cEPC and CAC counts were reduced in SCT and to study the in vitro effect of triiodothyronine (T3) on proangiogenic cell (PAC) function from young healthy controls.

METHODS

cEPCs (quantified by flow cytometry, 20 SCT/20 controls), CACs following in vitro cultures (15 SCT/14 controls), paracrine function of CACs, endothelial function by flow-mediated dilation (FMD, 9 SCT/9 controls), and the effect of T3 on apoptosis and endothelial nitric oxide synthase (eNOS) expression in PACs were studied.

RESULTS

p < 0.001, CD133⁺/VEGFR-2⁺ 0.4 (0.0-0.7) vs. 0.6 (0.0-4.6), p = 0.009, CD34⁺/VEGFR-2⁺ 0.3 (0.0-1.0) vs. 0.7 (0.1-4.9), p = 0.002; while CAC count was similar. SCT predicted a lower cEPC count after adjustment for conventional CVR factors. FMD was lower in SCT subjects versus controls (% mean ± SD, 2.7 ± 2.3 vs. 6.1 ± 2.3, p = 0.005). In vitro studies showed T3 increased early apoptosis and reduced eNOS expression in PACs.

CONCLUSIONS

In conclusion, SCT is associated with reduced cEPC count and FMD, confirming increased CVR in SCT. Future outcome trials are required to examine if treatment of this subclinical hyperactive state improves cardiovascular outcome.

CLINICAL TRIAL REGISTRATION

http://www.controlled-trials.com/isrctn/, identifier ISRCTN70334066.

Thyroid and heart, a clinically relevant relationship

BACKGROUND

Thyroid disorders, both overt and subclinical, are highly prevalent conditions in the general population. Although a clear relationship between overt thyroid dysfunctions and cardiovascular complications has long been established, data regarding subclinical thyroid dysfunction are by far more controversial.

PURPOSE

The present review will be aimed at providing a summary of most recent evidence coming from meta-analyses regarding the complex relationship between thyroid dysfunction and cardiovascular disease.

CONCLUSIONS

The review will summarize, in the first part, the physiopathological link between thyroid hormone imbalances and the cardiovascular system. In the second part the review will outline the evidence coming from meta-analyses regarding the cardiovascular risk related with both overt and subclinical thyroid dysfunctions. Particular attention will be put towards studies showing data stratified for patient's age, TSH levels and pre-existing cardiovascular disease. Finally, an overview regarding the effects of specific therapy for subclinical thyroid diseases in terms of amelioration of cardiovascular outcomes will be included.

Molecular Imaging for Thyrotoxicosis and Thyroid Nodules

After exclusion of exogenous iodine overload, radioiodine uptake (RAIU) testing with ¹²³I or ¹³¹I enables the accurate evaluation and quantification of iodine uptake and kinetics within thyroid cells. In addition, scintigraphic evaluation with ¹²³I or ^99mTc-pertechnetate (^99mTc04-) provides the topographic distribution of thyroid cell activity and allows the detection and localization of ectopic thyroid tissue. Destructive thyrotoxicosis is characterized by abolished or reduced uptake whereas productive thyrotoxicosis (i.e., hyperthyroidism "sensu strictu") is characterized by high RAIU with scintigraphically diffuse (i.e., Graves disease and diffuse thyroid autonomy) or focal (i.e., autonomously functioning thyroid nodules [AFTN]) overactivity. Accordingly, RAIU or thyroid scintigraphy are widely used to differentiate different causes of thyrotoxicosis. In addition, several radiopharmaceuticals are also available to help in differentiating benign from malignant thyroid nodules and inform clinical decision making. In fact, AFTNs can be safely excluded from fine-needle aspiration biopsy while either ^99mTc-methoxyisobutylisonitrile (MIBI) and ¹⁸F-FDG may complement the work-up of cytologically indeterminate cold nodules and contribute to reducing the need for diagnostic lobectomies/thyroidectomies. Finally, RAIU studies are also useful for calculating the administered therapeutic activity of ¹³¹I to treat hyperthyroidism and euthyroid multinodular goiter. All considered, thyroid molecular imaging allows us to characterize molecular/functional aspects of different thyroid diseases, even before clinical symptoms become manifest and remains integral to properly managing such conditions. Our present paper summarizes basic concepts, clinical applications, and potential developments of thyroid molecular imaging in patients affected by thyrotoxicosis and thyroid nodules.

Radioiodine therapy of thyroid autonomy

Radioiodine therapy (RIT) of thyroid functional autonomy (TFA) is rapidly evolving, though it has been recognized for decades as a very effective treatment of toxic nodular varieties. Indeed, TFA is a frequent cause of persistent subclinical hyperthyroidism, which should be regarded as a new metabolic syndrome, with well-established adverse cardio-vascular consequences. Sensitive TSH assays and multiparametric ultrasounds are not accurate enough to reliably diagnose TFA and identify its main variants, unifocal, multifocal (UFA/MFA) and disseminated autonomy (DISA). Modern diagnostic tools are extensively presented and rely upon Thyroid Scan imaging and quantification. A new relationship allows predicting at baseline, an excess of 123I uptake as compared to the TSH stimulation in compensated TFA. Suppressed TS are useful with either isotope, otherwise. Diagnosis of the DISA variant is presented as compared to Graves' disease. Dosimetry has some specificity in TFA work-up. Indeed, the spatial distribution of the dose is as important as the mean value itself and can be eventually controlled by adjusting the TSH level with the smart use of LT3 or antithyroid drug therapy (ATD). A review of the different ways to determine the target mass from anatomical to functional approaches is presented. Main clinical and dosimetric published results of RIT are summarized according to clinical goals. Endogenous TSH stimulation using an ATD preparation has promising results in reducing big autonomously functioning goiters. Finally, we report preliminary successful results of preventive RIT using short term LT3 suppression in compensated TFA, with low administered activities and low rate of hypothyroidism.

Outcomes of Thyroid Dysfunction in People Aged Eighty Years and Older: An Individual Patient Data Meta-Analysis of Four Prospective Studies (Towards Understanding Longitudinal International Older People Studies Consortium)

Background: Subclinical and overt thyroid dysfunction is easily detectable, often modifiable, and, in younger age groups, has been associated with clinically relevant outcomes. Robust associations in very old persons, however, are currently lacking. This study aimed to investigate the associations between (sub-)clinical thyroid dysfunction and disability in daily living, cognitive function, depressive symptoms, physical function, and mortality in people aged 80 years and older. Methods: Four prospective cohorts participating in the Towards Understanding Longitudinal International older People Studies (TULIPS) consortium were included. We performed a two-step individual participant data meta-analysis on source data from community-dwelling participants aged 80 years and older from the Netherlands, New Zealand, United Kingdom, and Japan. Outcome measures included disability in daily living (disability in activities of daily living [ADL] questionnaires), cognitive function (Mini-Mental State Examination [MMSE]), depressive symptoms (Geriatric Depression Scale [GDS]), physical function (grip strength) at baseline and after 5 years of follow-up, and all-cause five-year mortality. Results: Of the total 2116 participants at baseline (mean age 87 years, range 80-109 years), 105 participants (5.0%) were overtly hypothyroid, 136 (6.4%) subclinically hypothyroid, 1811 (85.6%) euthyroid, 60 (2.8%) subclinically hyperthyroid, and 4 (0.2%) overtly hyperthyroid. Participants with thyroid dysfunction at baseline had nonsignificantly different ADL scores compared with euthyroid participants at baseline and had similar MMSE scores, GDS scores, and grip strength. There was no difference in the change of any of these functional measures in participants with thyroid dysfunction during five years of follow-up. Compared with the euthyroid participants, no 5-year survival differences were identified in participants with overt hypothyroidism (hazard ratio [HR] 1.0, 95% confidence interval [CI 0.6-1.6]), subclinical hypothyroidism (HR 0.9 [CI 0.7-1.2]), subclinical hyperthyroidism (HR 1.1 [CI 0.8-1.7]), and overt hyperthyroidism (HR 1.5 [CI 0.4-5.9]). Results did not differ after excluding participants using thyroid-influencing medication. Conclusions: In community-dwelling people aged 80 years and older, (sub-)clinical thyroid dysfunction was not associated with functional outcomes or mortality and may therefore be of limited clinical significance.

Human immunodeficiency virus, diabetes mellitus and thyroid abnormalities: Should we be screening?

Background

Diabetes mellitus (DM) and human immunodeficiency virus (HIV) are associated with thyroid abnormalities. Scarce literature exists on the prevalence of thyroid abnormalities in people living with HIV (PLWH) and DM (PLWHD). Guidelines vary regarding thyroid-stimulating hormone (TSH) screening in PLWH and/or DM.

Objectives

This study describes thyroid abnormalities in PLWHD and HIV-uninfected people living with DM (PLWD).

Method

This was a cross-sectional analysis of demographic, clinical and biochemical data including TSH results of first-visit patients to the Edendale Hospital diabetes clinic between January 2016 and December 2017.

Results

A total of 915 patients were enrolled: 165 PLWHD and 750 PLWD. Overall prevalence of thyroid disorders in PLWD was 8.53% (64/750). The occurrence of ‘total’ thyroid disorders and of ‘subclinical-hypothyroidism’ (SCH) was higher in PLWHD than PLWD (23.03% vs. 8.53% and 20.61% vs. 4%, p < 0.001; respectively). People living with HIV and diabetes with thyroid disorders had lower CD4 counts than PLWHD without thyroid disorders (376.08 ± 333.30 vs. 509 ± 341.7 cells/mm³; p = 0.004). Subclinical-hypothyroidism was more common in patients on antiretroviral therapy [ART] (27/136 [19.85%] vs. 4/27 [14.81%], p < 0.001). A significant number of PLWHD acquired HIV before the onset of DM (107/165 [64.85%] vs. 58/165 [35.15%], p < 0.001). Patients on ART were more likely to develop DM, OR 2.66 (95% CI 1.11–6.38).

Conclusion

Our study showed an increased prevalence of thyroid disorders (especially SCH) in PLWD and a higher prevalence in PLWHD. Young, overweight, female PLWHD were at risk of SCH. People living with HIV and DM on ART demonstrated an increased prevalence of thyroid dysfunction and poor lipaemic control. The introduction of combined communicable–non-communicable disease clinics might provide an integrated patient screening option.

Novel Approaches to Air Pollution Exposure and Clinical Outcomes Assessment in Environmental Health Studies

An accurate assessment of pollutants’ exposure and precise evaluation of the clinical outcomes pose two major challenges to the contemporary environmental health research. The common methods for exposure assessment are based on residential addresses and are prone to many biases. Pollution levels are defined based on monitoring stations that are sparsely distributed and frequently distanced far from residential addresses. In addition, the degree of an association between outdoor and indoor air pollution levels is not fully elucidated, making the exposure assessment all the more inaccurate. Clinical outcomes’ assessment, on the other hand, mostly relies on the access to medical records from hospital admissions and outpatients’ visits in clinics. This method differentiates by health care seeking behavior and is therefore, problematic in evaluation of an onset, duration, and severity of an outcome. In the current paper, we review a number of novel solutions aimed to mitigate the aforementioned biases. First, a hybrid satellite-based modeling approach provides daily continuous spatiotemporal estimations with improved spatial resolution of 1 × 1 km2 and 200 × 200 m2 grid, and thus allows a more accurate exposure assessment. Utilizing low-cost air pollution sensors allowing a direct measurement of indoor air pollution levels can further validate these models. Furthermore, the real temporal-spatial activity can be assessed by GPS tracking devices within the individuals’ smartphones. A widespread use of smart devices can help with obtaining objective measurements of some of the clinical outcomes such as vital signs and glucose levels. Finally, human biomonitoring can be efficiently done at a population level, providing accurate estimates of in-vivo absorbed pollutants and allowing for the evaluation of body responses, by biomarkers examination. We suggest that the adoption of these novel methods will change the research paradigm heavily relying on ecological methodology and support development of the new clinical practices preventing adverse environmental effects on human health.

Prevalence of iatrogenic hypothyroidism in hyperthyroid cats treated with radioiodine using an individualised scoring system

OBJECTIVES

The aim of this study was to report the prevalence of iatrogenic hypothyroidism, with or without azotaemia, based on the measurement of serum total thyroxine (T4), thyroid-stimulating hormone (TSH) and creatinine concentrations, in hyperthyroid cats undergoing radioiodine (131I) treatment where the 131I dose was calculated using a previously described scoring system. A secondary aim of the study was to determine the positive and negative predictive values of serum T4 and TSH concentrations obtained 19 days after treatment in order to predict the development of iatrogenic hypothyroidism 6-9 months after 131I treatment.

METHODS

Serum T4, TSH and creatinine concentrations were measured 19 days and 6-9 months after 131I treatment. The prevalence of iatrogenic hypothyroidism was assessed with the results obtained 6-9 months after 131I treatment.

RESULTS

The prevalence of overt and subclinical hypothyroidism 6-9 months after 131I treatment was 40.0% (22/55 cats) and 12.7% (7/55 cats). Overt hypothyroidism with azotaemia was diagnosed in 8/55 (14.5%) cats. The positive and negative predictive values for the prediction of the development of iatrogenic hypothyroidism 6-9 months after 131I treatment were 72.2% and 80.0%, respectively, for a low serum T4 concentration, and 75.0% and 44.6%, respectively, for an increased serum TSH concentration.

CONCLUSIONS AND RELEVANCE

The use of an individualised scoring system is effective in determining the 131I dose for the treatment of hyperthyroid cats. However, the prevalence of overt hypothyroidism was higher in comparison with other studies using different dosing protocols. Further studies comparing the efficacy of individualised scoring systems and different fixed doses to determine which method is superior are warranted.

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.

Thyroid Hormone Profile in Children with Sepsis: Does Euthyroid Sick Syndrome Exist?

BACKGROUND:

Alterations in peripheral thyroid hormone metabolism play an eminent role in the development of the euthyroid sick syndrome. Altered solvation may also lead to changes in peripheral thyroid hormones. Data on thyroid hormones in critically ill children remain unclear.

AIM:

This study was aimed to evaluate thyroid hormone profile in children with sepsis as well as to assess the association between thyroid level and sepsis outcome.

METHODS:

An observational cohort study was conducted in 80 children with sepsis from October 2015 to January 2016 in Haji Adam Malik General Hospital. T3 and T4 level were measured on day 1 and after > 72 hours of sepsis diagnosed.

RESULTS:

We recorded length of stay in PICU, patient outcome and analysed the relationship with the chi-square test. Level of T3 and T4 were decreased on day 1 in pediatric sepsis. Of 80 subjects, 57 (71.2%) with low-level T3 and 41 (51.2%) with low T4 were found. The relationship between T3 and T4 level on day 1 with the length of stay were not found (P = 0.500; P = 0.987). There were a significant relationship between level of T3 and T4 with outcome (P = 0.0001; OR 24.706; P = 0.014; OR 3.086). Subject with normal T3 and T4 level had 24 and 3 times life chances compare to lower level.

CONCLUSION:

The Euthyroid Sick Syndrome in children with sepsis does exist. There was a significant relationship between T3 and T4 level on day 1 with patient outcome.

Thyroid Dysfunction and Cytological Patterns among Patients Requested for Thyroid Function Test in an Endemic Goiter Area of Gondar, North West Ethiopia

BACKGROUND

Thyroid dysfunction is the most common endocrine disorder in clinical practice, and about half of the population with thyroid dysfunction remains undiagnosed. There is a fairly wide spectrum of thyroid dysfunction, which can be identified by patterns of thyroid function test results. The prevalence of thyroid dysfunction among the population varies in different studies.

METHODS

A cross-sectional study was conducted from February 8th to April 8th, 2017, among patients who requested for the thyroid function test in an endemic goiter area at the Gondar Hospital, University of Gondar. A pretested structured questionnaire was used to collect the data. Three milliliters of blood samples was collected in a plain test tube and centrifuged for serum separation. The thyroid function test was done by using the MINI-VIDAS automation following the manufacturer manual (Setema PLC, Italy). Data were entered and analyzed using SPSS version 20. Descriptive statistics were used for data presentation, and P value < 0.05 was considered significant.

RESULT

Of the total 384 study participants, 346 (90.1%) were females and the study participants' mean age was 38 ± 13.9 years. The overall thyroid dysfunction prevalence was 26.3% (101): 1.6% was identified as subclinical hypothyroidism, 0.5% hypothyroidism, 9.6% subclinical hyperthyroidism, and 14.6% hyperthyroidism, and 23.4% had goiter. Furthermore, for cytological pattern analysis, 144 study participants who fulfilled indications for fine-needle aspiration cytology (FNAC) in thyroid nodules were included. Of the total, 3 (2.1%) had thyroid carcinoma, 46 (32%) had cystic degenerated follicular cells, and 82 (57%) had nodular thyroid goiter. In addition, a clinical presentation of a total of 144 study participants, showed lymphadenites in 7 participants (4.8%), hypertension in 9 (6.2%), and cardiac failure in 12 (8.3%).

CONCLUSION

The prevalence of thyroid dysfunction was high. The majority of thyroid dysfunction cases were newly diagnosed and more common in females. In addition, the most common disorders were subclinical hyperthyroidism and hyperthyroidism. Follicular cell with cyst degeneration and thyroid nodular goiter were the predominant FNAC findings. For early diagnosis and appropriate intervention in goiter endemic areas, the thyroid function test should be closely monitored.

Hormone treatments in congestive heart failure

The common ultimate pathological feature for all cardiovascular diseases, congestive heart failure (CHF), is now considered as one of the main public health burdens that is associated with grave implications. Neurohormonal systems play a critical role in cardiovascular homeostasis, pathophysiology, and cardiovascular diseases. Hormone treatments such as the newly invented dual-acting drug valsartan/sacubitril are promising candidates for CHF, in addition to the conventional medications encompassing beta receptor blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and mineralocorticoid receptor antagonists. Clinical trials also indicate that in CHF patients with low insulin-like growth factor-1 or low thyroid hormone levels, supplemental treatment with growth hormone or thyroid hormone seems to be cardioprotective; and in CHF patients with volume overload the vasopressin antagonists can relieve the symptoms superior to loop diuretics. Furthermore, a combination of selective glucocorticoid receptor agonist and mineralocorticoid receptor antagonist may be used in patients with diuretic resistance. Finally, the potential cardiovascular efficacy and safety of incretin-based therapies, testosterone or estrogen supplementation needs to be prudently evaluated in large-scale clinical studies. In this review, we briefly discuss the therapeutic effects of several key hormones in CHF.

Secondary and tertiary preventions of thyroid disease

INTRODUCTION

Secondary and tertiary preventions are concerned with the recognition of the disease process in a very early stage and delay in progression to complete disease and minimization of complications and the impact of illness.

METHODS

All articles related to secondary and tertiary prevention of thyroid diseases were reviewed. Using related key words, articles published between 2001 and 2015 were evaluated, categorized, and analyzed.

RESULTS

In secondary prevention, congenital hypothyroidism and subclinical hypo and hyperthyroidism are equally important. Routine screening of patients with multinodular goiter by either ultrasonography or calcitonin is a controversial issue, while calcitonin assessments in medullary cancer and RET in family members are recommended. Screening of thyroid disease in pregnancy is limited to those with risk factors. Views regarding the importance of thyroid autoimmunity in secondary prevention are also presented. In tertiary prevention, prescribing excessive doses of levothyroxine, in the elderly in particular and appropriate care of all patients to avoid progression and complications are the key issues.

CONCLUSION

Optimization of management of thyroid diseases requires timely screening, prevention of progression to more sever disease, optimal medical care, and avoidance of iatrogenic conditions.

The Effect of Thyroid Dysfunction on the Cardiovascular Risk of Type 2 Diabetes Mellitus Patients in Ghana

BACKGROUND

Thyroid dysfunction is known to exaggerate the coronary heart disease (CHD) risk associated with type 2 diabetes mellitus (T2DM) among whites. The effect is yet to be studied among African populations.

METHODS

This is a cross-sectional study involving 780 T2DM patients enrolled in a diabetes clinic in Kumasi, Ghana. CHD risk was estimated using the Framingham and UKPDS risk scores. Risks were categorised as low (<10%), intermediate (10-19%), and high (≥20%). Associations between metabolic risk factors, thyroid dysfunction, and CHD risk were measured using Spearman's partial correlation analysis while controlling for age and gender. Differences were considered statistically significant at p < 0.05.

RESULTS

780 T2DM patients (57.7% females), mean ± SD age of 57.4 ± 9.4 was analysed. The median (IQR) 10-year CHD score estimated using the Framingham and UKPDS risk engines for males and females was 12 (8-20), 9.4 (5.7-13.4), p < 0.0001 and 3 (1-6), 5.8 (3.4-9.6), p < 0.0001, respectively. Positive correlation was found between CHD risk and HbA1c, total cholesterol, low-density lipoprotein cholesterol, systolic blood pressure, and thyroid stimulating hormone.

CONCLUSION

The presence of thyroid dysfunction significantly increased the CHD risk associated with T2DM patients in Ghana.

Pre-admission TSH levels predict long-term mortality in adults treated for hypothyroidism

CONTEXT

Limited data is available regarding the association between pre-admission thyroid function and prognosis of hospitalized patients treated for hypothyroidism.

OBJECTIVE

Evaluate an association between thyroid stimulating hormone (TSH) levels and mortality in hospitalized levothyroxine-treated patients.

DESIGN AND SETTING

Observational data of patients admitted to medical wards between 2011 and 2013. TSH levels obtained up to 180 days prior to admission were stratified as follows: low (≤0.5 mIU/L), normal (0.5-5 mIU/L), high (>5 mIU/L).

PATIENTS

Patients aged 60-80 years with available thyroid function tests were matched with controls without hypothyroidism.

MAIN OUTCOME

All-cause mortality up to 66-months following discharge.

RESULTS

One thousand and fifty seven patients (73% females, mean (SD) age 71 ± 6 years) were matched with controls without hypothyroidism. Mean hospital stay and in-hospital mortality were not different between groups. Mortality risk at the end-of-follow-up was 41% (438/1057) and 37% (392/1057) for patients with and without hypothyroidism (p < 0.05). TSH levels were classified as follows: low, 84 patients (8%); normal, 667 patients (63%); high, 306 patients (29%). Length of hospitalization and in-hospital mortality were not different between TSH categories. Mortality risk at the end-of-follow-up was 30, 39, and 50% with low, normal and elevated TSH, respectively. Adjusted hazard ratio (95% CI) of mortality at the end-of-follow-up was of 2.2 (1.2-3.8) for high vs. low TSH levels, and 1.4 (1.1-1.9) for high vs. normal TSH levels.

CONCLUSION

In treated hypothyroid adult patients, increased TSH up to 6 months prior to admission is associated with increased mortality. Treatment should aim at achieving euthyroidism to improve survival.

Thyroid status and mortality in nonagenarians from long-lived families and the general population

The relationship between thyroid status and longevity has been investigated extensively. However, data on thyroid status and survival in old age is scarce. In this study we investigated associations of different parameters of thyroid status with mortality in nonagenarians, and whether these associations were different in nonagenarians from long-lived families than in nonagenarians from the general population. In total, 805 nonagenarians from the Leiden Longevity Study and 259 nonagenarians from the Leiden 85-plus Study were followed up to collect mortality data. At baseline, levels of thyrotropin (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) were measured. In nonagenarians from long-lived families and from the general population, associations between thyroid parameters and mortality were similar. We found no interaction between study population and parameters of thyroid status on mortality (P-values>0.70). The results from both studies were combined to derive generalizable associations. Hazard ratios (HRs) for the highest compared to lowest tertiles were determined, resulting in TSH HR 0.91 (P=0.25), fT4 HR 1.22 (P=0.02), fT3 HR 0.74 (P=1.31e-4), and fT3/fT4 HR 0.66 (P=5.64e-7). In conclusion, higher fT3/fT4 ratios, higher levels of fT3, and lower levels of fT4 were associated with lower mortality rate in nonagenarians and independent of familial longevity status.

MANAGEMENT OF ENDOCRINE DISEASE: l-Thyroxine replacement therapy in the frail elderly: a challenge in clinical practice

The number of elderly people, mostly aged over 85 years (the 'oldest old'), is increasing worldwide. As a consequence, accompanying morbidity and disability have been increasing, and frailty, defined as an age-related condition of decline of physiological reserves and vulnerability, represents an emerging problem. Caring for older frail people may represent a challenge, since the elderly differ significantly from younger adults in terms of comorbidity, polypharmacy, pharmacokinetics and greater vulnerability to adverse drug reactions. Specific criteria of therapeutic appropriateness and modified goals of care are needed in such patients, also in endocrine care settings. Indeed, thyroid dysfunctions are among the most common conditions in older, multimorbid populations. The prevalence of overt and subclinical hypothyroidism is as high as 20% and thyroid hormone prescription is common in the elderly, with a trend toward levothyroxine treatment of more marginal degrees of hypothyroidism. In addition, older patients have the highest rate of overtreatment during replacement therapy and are more susceptible to developing adverse effects from thyroid hormone excess. Recently, results of a multicentric randomized controlled trial, the TRUST-IEMO collaboration trial, added further insights to the debated question of whether and when levothyroxine treatment is required and if it is beneficial in the elderly. With this in mind, we revised the relevant literature on the impact of thyroid dysfunction and replacement therapy among older people, with the aim to better define indications, benefits and risks of l-T4 replacement therapy in the frail elderly.

Excess Mortality in Treated and Untreated Hyperthyroidism Is Related to Cumulative Periods of Low Serum TSH

INTRODUCTION AND AIM

Cumulative time-dependent excess mortality in hyperthyroid patients has been suggested. However, the effect of antithyroid treatment on mortality, especially in subclinical hyperthyroidism, remains unclarified. We investigated the association between hyperthyroidism and mortality in both treated and untreated hyperthyroid individuals.

PATIENTS AND METHODS

Register-based cohort study of 235,547 individuals who had at least one serum thyroid-stimulating hormone (TSH) measurement in the period 1995 to 2011 (7.3 years median follow-up). Hyperthyroidism was defined as at least two measurements of low serum TSH. Mortality rates for treated and untreated hyperthyroid subjects compared with euthyroid controls were calculated using multivariate Cox regression analyses, controlling for age, sex, and comorbidities. Cumulative periods of decreased serum TSH were analyzed as a time-dependent covariate.

RESULTS

Hazard ratio (HR) for mortality was increased in untreated [1.23; 95% confidence interval (CI), 1.12 to 1.37; P < 0.001], but not in treated, hyperthyroid patients. When including cumulative periods of TSH in the Cox regression analyses, HR for mortality per every 6 months of decreased TSH was 1.11 (95% CI, 1.09 to 1.13; P < 0.0001) in untreated hyperthyroid patients (n = 1137) and 1.13 (95% CI, 1.11 to 1.15; P < 0.0001) in treated patients (n = 1656). This corresponds to a 184% and 239% increase in mortality after 5 years of decreased TSH in untreated and treated hyperthyroidism, respectively.

CONCLUSIONS

Mortality is increased in hyperthyroidism. Cumulative periods of decreased TSH increased mortality in both treated and untreated hyperthyroidism, implying that excess mortality may not be driven by lack of therapy, but rather inability to keep patients euthyroid. Meticulous follow-up during treatment to maintain biochemical euthyroidism may be warranted.

MANAGEMENT OF ENDOCRINE DISEASE: Subclinical thyrotoxicosis: prevalence, causes and choice of therapy

Subclinical thyrotoxicosis is a condition affecting up to 10% of the population in some studies. We have reviewed literature and identified studies describing prevalences, causes and outcomes of this condition. Treatment should be considered in all subjects if this biochemical abnormality is persistent, especially in case of symptoms of thyrotoxicosis or in the presence of any complication. In particular, treatment should be offered in those subclinically thyrotoxic patients with a sustained serum TSH below 0.1 U/L. However it is important to recognise that there are no large controlled intervention studies in the field and thus there is no high quality evidence to guide treatment recommendations. In particular, there is no evidence for therapy and there is weak evidence of harm from thyrotoxicosis if serum TSH is in the 0.1-0.4 IU/L range. In this review, we describe the different causes of subclinical thyrotoxicosis, and how treatment should be tailored to the specific cause. We advocate radioactive iodine treatment to be the first-line treatment in majority of patients suffering from subclinical thyrotoxicosis due to multinodular toxic goitre and solitary toxic adenoma, but we do generally not recommend it as the first-line treatment in patients suffering from subclinical Graves' hyperthyroidism. Such patients may benefit mostly from antithyroid drug therapy. Subclinical thyrotoxicosis in early pregnancy should in general be observed, not treated. Moreover, we advocate a general restriction of therapy in cases where no specific cause for the presumed thyroid hyperactivity has been proven.

What is the association of hypothyroidism with risks of cardiovascular events and mortality? A meta-analysis of 55 cohort studies involving 1,898,314 participants

BACKGROUND

Whether hypothyroidism is an independent risk factor for cardiovascular events is still disputed. We aimed to assess the association between hypothyroidism and risks of cardiovascular events and mortality.

METHODS

We searched PubMed and Embase from inception to 29 February 2016. Cohort studies were included with no restriction of hypothyroid states. Priori main outcomes were ischemic heart disease (IHD), cardiac mortality, cardiovascular mortality, and all-cause mortality.

RESULTS

Fifty-five cohort studies involving 1,898,314 participants were identified. Patients with hypothyroidism, compared with euthyroidism, experienced higher risks of IHD (relative risk (RR): 1.13; 95% confidence interval (CI): 1.01-1.26), myocardial infarction (MI) (RR: 1.15; 95% CI: 1.05-1.25), cardiac mortality (RR: 1.96; 95% CI: 1.38-2.80), and all-cause mortality (RR: 1.25; 95% CI: 1.13-1.39); subclinical hypothyroidism (SCH; especially with thyrotropin level ≥10 mIU/L) was also associated with higher risks of IHD and cardiac mortality. Moreover, cardiac patients with hypothyroidism, compared with those with euthyroidism, experienced higher risks of cardiac mortality (RR: 2.22; 95% CI: 1.28-3.83) and all-cause mortality (RR: 1.51; 95% CI: 1.26-1.81).

CONCLUSIONS

Hypothyroidism is a risk factor for IHD and cardiac mortality. Hypothyroidism is associated with higher risks of cardiac mortality and all-cause mortality compared with euthyroidism in the general public or in patients with cardiac disease.

Elevated TSH in adults treated for hypothyroidism is associated with increased mortality

CONTEXT

Numerous studies investigated the link between hypothyroidism and mortality, but a definite conclusion is hard to reach as these were limited by a number of factors, including age of participants, comorbidities and single measurement of thyroid function.

OBJECTIVE

To evaluate the association between TSH and fT4 levels and mortality in patients with levothyroxine-treated hypothyroidism.

DESIGN AND SETTING

Observational data of hospitalized patients (2011-2014). TSH and fT4 levels obtained between at least 30 days after discharge and until death or end of follow-up were collected. Median TSH and fT4 levels were stratified into categories.

PATIENTS

In total, 611 patients with treated hypothyroidism, aged 60-80 years (72% females, mean age 71 ± 6 years) were included in the study.

MAIN OUTCOME MEASURE

All-cause mortality up to 66 months after discharge, by TSH and fT4 categories.

RESULTS

During follow-up, the average numbers of TSH and fT4 measurements were 5.5 ± 3.8 and 2.5 ± 4.2 per patient respectively. Mortality rates were 28%, 29% and 54% with median TSH of 0.5-2.5, 2.5-5.0 and 5.0-10.0 IU/L respectively. Adjusted hazard ratios for mortality with median TSH between 5.0 and 10.0 IU/L were 2.3 (95% CI: 1.6-3.4) and 2.2 (95% CI: 1.6-3.2) compared with patients with TSH between 0.5-2.5 IU/L and 2.5-5 IU/L respectively. There was no difference in mortality between patients with median fT4 10-15 or 15-20 pmol/L.

CONCLUSION

In treated hypothyroid adult patients and serial measurements of thyroid function tests, median TSH levels of 5-10 IU/L are associated with increased mortality with no effect of fT4 levels. Treatment should aim at achieving euthyroidism to improve survival.

Relationship between Subclinical Thyroid Dysfunction and the Risk of Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

BACKGROUND

Evidence on the association between subclinical thyroid dysfunction and the risk of cardiovascular outcomes are conflicting.

METHODS AND RESULTS

PubMed, EMbase, Web of Science, Cochrane Library, and China Biology Medicine (CBM) databases were searched from inception to July 10, 2016. A total of 16 studies were included for meta-analysis. We found that subclinical hypothyroidism was not correlated with coronary heart disease (CHD) (RR = 1.17; 95% CI, 0.91-1.52), total mortality (RR = 1.02; 95% CI, 0.93-1.13), cardiovascular mortality (RR = 1.06; 95% CI, 0.77-1.45), heart failure (RR = 1.17; 95% CI, 0.87-1.57), and atrial fibrillation (RR = 1.05; 95% CI, 0.91-1.21), except CHD mortality (RR = 1.37; 95% CI, 1.03-1.84). Subgroup analysis indicated a higher estimation risk in CHD (RR = 1.54; 95% CI, 1.00-2.39), cardiovascular mortality (RR = 2.14; 95% CI, 1.43-3.22), and CHD mortality (RR = 1.54; 95% CI, 1.11-2.15) among participants < 65 years. Furthermore, subclinical hyperthyroidism was found to be associated with CHD (RR = 1.20; 95% CI, 1.02-1.42), total mortality (RR = 1.27; 95% CI, 1.07-1.51), and CHD mortality (RR = 1.45; 95% CI, 1.12-1.86).

CONCLUSIONS

Subclinical hypothyroidism is likely associated with an increased risk of CHD mortality, and subclinical hyperthyroidism is likely associated with increased risk of CHD, CHD mortality, and total mortality.

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.

Thyroid Function Test Derangements and Mortality in Dialysis Patients: A Systematic Review and Meta-analysis

BACKGROUND

We evaluated current evidence associating thyroid function test result derangements with risk for mortality in patients with chronic kidney failure treated by long-term dialysis.

STUDY DESIGN

Systematic review and meta-analysis of cohort studies.

SETTING & POPULATION

Dialysis patients.

SELECTION CRITERIA FOR STUDIES

We searched PubMed, Web of Science, Science Citation Index, Cochrane Library, and Embase databases from inception through December 2015.

PREDICTORS

Hypothyroidism (thyrotropin level greater than reference range) and low triiodothyronine (T₃) and thyroxine (T₄) levels.

OUTCOMES

All-cause and cardiovascular mortality.

RESULTS

12 studies involving 14,766 participants (4,450 deaths) were identified. Of those, 6 studies provided data for cardiovascular mortality (2,772 participants with 327 cardiovascular deaths). Overall, confidence in the available evidence was moderate. Pooled adjusted HRs for all-cause mortality associated with hypothyroidism, low T₃ level, and low T₄ level were 1.24 (95% CI, 1.14-1.34), 1.67 (95% CI, 1.23-2.27), and 2.40 (95% CI, 1.47-3.93), respectively. Pooled adjusted HRs for cardiovascular mortality associated with low T₃ and T₄ levels were 1.84 (95% CI, 1.24-2.74) and 3.06 (95% CI, 1.29-7.24), respectively.

LIMITATIONS

Fewer studies reporting on T₄ and thyrotropin outcomes.

CONCLUSIONS

In patients treated with long-term dialysis, (cardiovascular) mortality is consistently higher in the presence of thyroid function test result derangements.

Iodinated Contrast Medium Exposure During Computed Tomography Increase the Risk of Subsequent Development of Thyroid Disorders in Patients Without Known Thyroid Disease: A Nationwide Population-Based, Propensity Score-Matched, Longitudinal Follow-Up Study

To investigate the association between iodinated contrast medium (ICM) exposure during computed tomography (CT) and the subsequent development of thyroid disorders in patients without known thyroid disease in Taiwan, an iodine-sufficient area. We conducted a population-based cohort study by using data from 1996 to 2012 in the Taiwan National Health Insurance Research Database. A total of 33,426 patients who underwent ICM-enhanced CT were included as the study cohort. To avoid selection bias, we used propensity score and matched for the index year (defined as the year of first ICM exposure) to retrieve 33,426 patients as the comparison cohort. No patients in the 2 cohorts had any known thyroid disease before the index year. Patients with a history of amiodarone treatment or coronary angiography and those with <1 year follow-up were excluded. Participants were followed until a new diagnosis of thyroid disorder or December 31, 2011. Hazard ratios (HRs) with 95% confidence interval (95% CI) were calculated using the Cox proportional hazards regression. An association was identified between ICM exposure and the subsequent development of thyroid disorders after adjustment for potential confounders (adjusted HR = 1.17; 95% CI: 1.07-1.29; P = 0.001). Male patients and patients' ages ≥40 years in the ICM-exposure cohort had a higher adjusted HR for developing thyroid disorders than did those in the non-ICM-exposure cohort. Hypothyroidism had the highest adjusted HR (HR = 1.37; 95% CI: 1.06-1.78; P < 0.05) among all thyroid disorders and had a higher risk of development or detection during >0.5-year post-ICM exposure compared with that during ≤0.5-year post-ICM exposure (HR = 1.26; 95% CI: 1.01-1.58; P < 0.05). Repeated ICM exposure increased the risk of thyroid disorders in patients who accepted >1 time of ICM per year on average compared with those who accepted ≤1 time per year on average (adjusted HR = 3.04; 95% CI: 2.47-3.73; P < 0.001). This study identified ICM exposure during CT as a risk factor for the subsequent development of thyroid disorders in patients without known thyroid disease, particularly in patients with repeated exposure.

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.

Thyroid functional disease: an under-recognized cardiovascular risk factor in kidney disease patients

Thyroid functional disease, and in particular hypothyroidism, is highly prevalent among chronic kidney disease (CKD) and end-stage renal disease (ESRD) patients. In the general population, hypothyroidism is associated with impaired cardiac contractility, endothelial dysfunction, atherosclerosis and possibly higher cardiovascular mortality. It has been hypothesized that hypothyroidism is an under-recognized, modifiable risk factor for the enormous burden of cardiovascular disease and death in CKD and ESRD, but this has been difficult to test due to the challenge of accurate thyroid functional assessment in uremia. Low thyroid hormone levels (i.e. triiodothyronine) have been associated with adverse cardiovascular sequelae in CKD and ESRD patients, but these metrics are confounded by malnutrition, inflammation and comorbid states, and hence may signify nonthyroidal illness (i.e. thyroid functional test derangements associated with underlying ill health in the absence of thyroid pathology). Thyrotropin is considered a sensitive and specific thyroid function measure that may more accurately classify hypothyroidism, but few studies have examined the clinical significance of thyrotropin-defined hypothyroidism in CKD and ESRD. Of even greater uncertainty are the risks and benefits of thyroid hormone replacement, which bear a narrow therapeutic-to-toxic window and are frequently prescribed to CKD and ESRD patients. In this review, we discuss mechanisms by which hypothyroidism adversely affects cardiovascular health; examine the prognostic implications of hypothyroidism, thyroid hormone alterations and exogenous thyroid hormone replacement in CKD and ESRD; and identify areas of uncertainty related to the interplay between hypothyroidism, cardiovascular disease and kidney disease requiring further investigation.

Evaluation of thyroid-stimulating hormone, total thyroxine, and free thyroxine concentrations in hyperthyroid cats receiving methimazole treatment

Background

Iatrogenic hypothyroidism (IH) after treatment of hyperthyroidism can impair renal function. No study compared the efficacy of measurement of serum free thyroxine by equilibrium dialysis (fT4ed) or thyroid‐stimulating hormone (TSH) concentrations for monitoring cats receiving methimazole.

Objectives

To (1) compare the ability of total T4 and fT4ed concentrations in conjunction with TSH to define thyroid function in hyperthyroid cats receiving methimazole, (2) determine the prevalence of IH in cats receiving methimazole, and (3) examine the relationship between thyroid axis hormones and serum creatinine concentration.

Animals

One hundred and twenty‐five serum samples from hyperthyroid cats receiving methimazole and total T4 concentrations ≤3.9 μg/dL.

Methods

Total T4, fT4ed, and TSH concentrations were measured to evaluate thyroid status and serum creatinine concentration was measured to assess renal function. A low total T4 or fT4ed concentration in combination with an increased TSH concentration defined IH.

Results

Forty‐one cats (33%) had increased TSH concentrations. Of cats with total T4 and fT4ed concentrations below the reference range, 68% and 73%, respectively, had TSH concentrations above the reference range. Only 18% of cats with a normal TSH concentration had an increased serum creatinine concentrations as compared to 39% of those with increased TSH concentrations (P < .001).

Conclusions

Free T4ed does not identify more cats with potential IH as compared to total T4. The IH prevalence was approximately 20%. Measurement of TSH may be more helpful in indicating that azotemia, if present, is at least in part related to IH. Investigation is needed to define TSH assay utility in identifying possible subclinical IH.

Treatment of subclinical hyperthyroidism: effect on left ventricular mass and function of the heart using magnetic resonance imaging technique

PURPOSE

The aim of this study was to investigate structure and function of the heart in subclinical hyperthyroidism (SH) before and after obtaining euthyroidism by radioactive iodine treatment, using high precision and observer-independent magnetic resonance imaging (MRI) technology.

METHODS

Cardiac MRI was performed before and after euthyroidism was obtained by radioactive iodine treatment in 12 otherwise healthy patients (11 women and one man, mean age 59 years, range 44-71 years) with a nodular goiter and SH, and compared with eight healthy controls investigated at baseline. Cardiac data were expressed as an index, as per body surface area, except for heart rate (HR) and ejection fraction.

RESULTS

Post-treatment cardiac MRI was performed in median 139 days after a normalized serum TSH value had been recorded. During treatment, serum TSH increased from (median (range)) 0.01 (0.01-0.09) to 0.88 (0.27-3.99) mU/l. Patients with untreated SH had increased resting HR (P<0.01) as well as cardiac index (cardiac output as per body surface area) (P<0.01) compared with controls. Obtaining euthyroidism resulted in a significant decrease in left ventricular mass index (LVMI) of 2.7 g/m(2) (P=0.034), in HR of 8 bpm (P=0.001), and in cardiac index of 0.24 l/min per m(2) (P=0.017).

CONCLUSIONS

Normalization of thyroid function by radioactive iodine treatment of SH resulted in significant reductions in clinically important heart parameters such as LVMI, HR, and cardiac index. SH should be regarded as a condition in which aggressive treatment should be considered to protect cardiac function.

[Impact of thyroid function on fertility]

Until recently, anovulation or recurrent miscarriages were the only situations for screening a thyroid dysfunction in an infertile patient. Recent U.S. guidelines published in 2011 identify infertile women as being at risk for thyroid dysfunction. This paper proposes, on the occasion of the new recommendations, a review of the literature data on the known impact of thyroid dysfunction on fertility, on the first trimester of pregnancy and on the way to treat them.

Multiple hormonal dysregulation as determinant of low physical performance and mobility in older persons

Mobility-disability is a common condition in older individuals. Many factors, including the age-related hormonal dysregulation, may concur to the development of disability in the elderly. In fact, during the aging process it is observed an imbalance between anabolic hormones that decrease (testosterone, dehydroepiandrosterone sulphate (DHEAS), estradiol, insulin like growth factor-1 (IGF-1) and Vitamin D) and catabolic hormones (cortisol, thyroid hormones) that increase. We start this review focusing on the mechanisms by which anabolic and catabolic hormones may affect physical performance and mobility. To address the role of the hormonal dysregulation to mobility-disability, we start to discuss the contribution of the single hormonal derangement. The studies used in this review were selected according to the period of time of publication, ranging from 2002 to 2013, and the age of the participants (≥65 years). We devoted particular attention to the effects of anabolic hormones (DHEAS, testosterone, estradiol, Vitamin D and IGF-1) on both skeletal muscle mass and strength, as well as other objective indicators of physical performance. We also analyzed the reasons beyond the inconclusive data coming from RCTs using sex hormones, thyroid hormones, and vitamin D (dosage, duration of treatment, baseline hormonal values and reached hormonal levels). We finally hypothesized that the parallel decline of anabolic hormones has a higher impact than a single hormonal derangement on adverse mobility outcomes in older population. Given the multifactorial origin of low mobility, we underlined the need of future synergistic optional treatments (micronutrients and exercise) to improve the effectiveness of hormonal treatment and to safely ameliorate the anabolic hormonal status and mobility in older individuals.

Restoration of thyroid hormone balance: a game changer in the treatment of heart failure?

The link between low thyroid hormone (TH) function and heart failure is reviewed in the present report. The idea that TH dysfunction may contribute to diseases leading to HF has been discussed for over 60 yr. A growing body of evidence from animal and human studies, particularly in recent years, suggests that TH treatment may improve clinical outcomes. Indeed, if a similar amount of positive information were available for a newly developed heart drug, there is little doubt that large-scale clinical trials would be underway with considerable excitement. THs offer the promise of improving ventricular contraction and relaxation, improving coronary blood flow, and inhibiting atherosclerosis, and new results suggest they may even reduce the incidence of arrhythmias in heart diseases. Are the potential clinical benefits worth the risk of possible overdosing? After so many years, why has this question not been answered? Clearly, the concept has not been disproven. This review explores the body of clinical evidence related to TH dysfunction and heart failure, discuss insights into pathophysiological, cellular, and molecular mechanisms provided by animal research, and discuss what is needed to resolve this long-standing issue in cardiology and move forward.

Duration of thyroid dysfunction correlates with all-cause mortality. the OPENTHYRO Register Cohort

Introduction and Aim

The association between thyroid dysfunction and mortality is controversial. Moreover, the impact of duration of thyroid dysfunction is unclarified. Our aim was to investigate the correlation between biochemically assessed thyroid function as well as dysfunction duration and mortality.

Methods

Register-based follow-up study of 239,768 individuals with a serum TSH measurement from hospitals and/or general practice in Funen, Denmark. Measurements were performed at a single laboratory from January 1st 1995 to January 1st 2011. Cox regression was used for mortality analyses and Charlson Comorbidity Index (CCI) was used as comorbidity score.

Results

Hazard ratios (HR) with 95% confidence intervals (CI) for mortality with decreased (<0.3 mIU/L) or elevated (>4.0 mIU/L) levels of TSH were 2.22; 2.14–2.30; P<0.0001 and 1.28; 1.22–1.35; P<0.0001, respectively. Adjusting for age, gender, CCI and diagnostic setting attenuated the risk estimates (HR 1.23; 95% CI: 1.19–1.28; P<0.0001, mean follow-up time 7.7 years, and HR 1.07; 95% CI: 1.02–1.13; P = 0.004, mean follow-up time 7.2 years) for decreased and elevated values of TSH, respectively. Mortality risk increased by a factor 1.09; 95% CI: 1.08–1.10; P<0.0001 or by a factor 1.03; 95% CI: 1.02–1.04; P<0.0001 for each six months a patient suffered from decreased or elevated TSH, respectively. Subdividing according to degree of thyroid dysfunction, overt hyperthyroidism (HR_overt 1.12; 95% CI: 1.06–1.19; P<0.0001), subclinical hyperthyroidism (HR_subclinical 1.09; 95% CI: 1.02–1.17; P = 0.02) and overt hypothyroidism (HR_overt 1.57; 95% CI: 1.34–1.83; P<0.0001), but not subclinical hypothyroidism (HR_subclinical 1.03; 95% CI: 0.97–1.09; P = 0.4) were associated with increased mortality.

Conclusions and Relevance

In a large-scale, population-based cohort with long-term follow-up (median 7.4 years), overt and subclinical hyperthyroidism and overt but not subclinical hypothyroidism were associated with increased mortality. Excess mortality with increasing duration of decreased or elevated serum TSH suggests the importance of timely intervention in individuals with thyroid dysfunction.

Bone health and clinical results after hip fracture surgery in patients with subclinical hypothyroidism

Background

Subclinical thyroid dysfunction might influence a bone health. We evaluated whether subclinical hypothyroidism adversely affects bone health including bone mineral density (BMD), level of vitamin D, and bone turnover status in patients with hip fracture.

Methods

We evaluated 471 patients aged 50 years or older, who underwent hip fracture surgeries. BMD, level of vitamin D, bone turnover status, and one-year mortality were compared between subclinical hypothyroidism group and control group.

Results

BMD of femur and the level of 25-hydroxy-vitamin D (25-[OH]D) were similar in the two groups. There were no significant differences in bone turnover markers according to thyroid function. No significant differences were observed between the groups in utilization of intensive care unit (ICU), length of hospital stay, mobility, and one-year mortality.

Conclusions

Subclinical hypothyroidism was not associated with reduced bone health, including BMD, the level of 25-(OH)D, and bone turnover marker.

Associations between thyroid function and mortality: the influence of age

OBJECTIVE

The aim of this study was to investigate the influence of age on the association between thyroid function and mortality.

DESIGN

The Nijmegen Biomedical Study is a population-based study, comprising 5816 randomly selected adults of all age groups without previously known thyroid disease.

METHODS

TSH, free thyroxine (FT4) and peroxidase antibodies were measured in 2002-2003. The number of deaths were established in 2012 (median follow-up time 9.4 years).

RESULTS

Subclinical thyrotoxicosis was associated with mortality in subjects aged <65 years (hazard ratio (HR) 2.5, 95% CI 1.1-5.7), but not in subjects aged >65 years. As for thyroid function within the normal range: in the 493 participants aged 80 years or older, an FT4 level in the high-normal range (18.5-22 pmol/l) was associated with a higher mortality in comparison with FT4 levels in the middle range (11.5-15.0 pmol/l): HR 1.7 (95% CI 1.0-2.9). In these elderly, TSH levels within the high-normal range (3.0-4.0 mIU/l) were also associated with a higher mortality in comparison with TSH levels within the middle range (1.0-2.0 mIU/l): HR 1.8 (95% CI 1.0-3.1).

CONCLUSIONS

The relationship between thyroid function and mortality differs according to age. This finding might (partially) explain the discrepant results of previous studies examining the relationship between thyroid function and mortality in different age groups.

Clinical practice guidelines for the management of hypothyroidism

INTRODUCTION

Hypothyroidism has long been known for its effects on different organ systems, leading to hypometabolism. However, subclinical hypothyroidism, its most prevalent form, has been recently related to cardiovascular risk and also to maternal-fetal complications in pregnant women.

OBJECTIVES

In these clinical practice guidelines, several aspects of this field have been discussed with the clear objectives of helping physicians treat patients with hypothyroidism, and of sharing some of our Latin American-based clinical experience.

MATERIALS AND METHODS

The Latin American Thyroid Society commissioned a Task Force on Hypothyroidism to develop evidence-based clinical guidelines on hypothyroidism. A systematic review of the available literature, focused on the primary databases of MedLine/PubMed and Lilacs/SciELO was performed. Filters to assess methodological quality were applied to select the best quality studies. The strength of recommendation on a scale from A-D was based on the Oxford Centre for Evidence--based Medicine, Levels of Evidence 2009, allowing an unbiased opinion devoid of subjective viewpoints. The areas of interest for the studies comprised diagnosis, screening, treatment and a special section for hypothyroidism in pregnancy.

RESULTS

Several questions based on diagnosis, screening, treatment of hypothyroidism in adult population and specifically in pregnant women were posed. Twenty six recommendations were created based on the answers to these questions. Despite the fact that evidence in some areas of hypothyroidism, such as therapy, is lacking, out of 279 references, 73% were Grade A and B, 8% Grade C and 19% Grade D.

CONCLUSIONS

These evidence-based clinical guidelines on hypothyroidism will provide unified criteria for management of hypothyroidism throughout Latin America. Although most of the studies referred to are from all over the world, the point of view of thyroidologists from Latin America is also given.

Subclinical and overt thyroid dysfunction and risk of all-cause mortality and cardiovascular events: a large population study

CONTEXT

Thyroid dysfunction has been associated with both increased all-cause and cardiovascular mortality, but limited data are available on mild thyroid dysfunction and cause-specific mortality.

OBJECTIVE

The objective of the study was to examine the risk of all-cause mortality, major adverse cardiovascular events (MACEs), and cause-specific events in subjects with overt and subclinical thyroid dysfunction.

DESIGN

This was a retrospective cohort study.

SETTING AND PARTICIPANTS

Participants in the study were subjects who underwent thyroid blood tests, without prior thyroid disease, consulting their general practitioner in 2000-2009 in Copenhagen, Denmark.

MAIN OUTCOME MEASURE

All-cause mortality, MACEs, and cause-specific events identified in nationwide registries were measured.

RESULTS

A total of 47 327 (8.4%) deaths occurred among 563 700 included subjects [mean age 48.6 (SD ± 18.2) y; 39% males]. All-cause mortality was increased in overt and subclinical hyperthyroidism [age adjusted incidence rates of 16 and 15 per 1000 person-years, respectively; incidence rate ratios (IRRs) 1.25 [95% confidence interval (CI) 1.15-1.36] and 1.23 (95% CI 1.16-1.30)] compared with euthyroid (incidence rate of 12 per 1000 person-years). Risk of MACEs was elevated in overt and subclinical hyperthyroidism [IRRs 1.16 (95% CI 1.05-1.27) and 1.09 (95% CI 1.02-1.16)] driven by heart failure [IRRs 1.14 (95% CI 0.99-1.32) and 1.20 (95% CI 1.10-1.31)]. A reduction of all-cause mortality was observed in subclinical hypothyroidism with TSH of 5-10 mIU/L [IRR 0.92 (95% CI 0.86-0.98)].

CONCLUSIONS

Heart failure is the leading cause of an increased cardiovascular mortality in both overt and subclinical hyperthyroidism. Subclinical hypothyroidism with TSH 5-10 mIU/L might be associated with a lower risk of all-cause mortality.

Endobiogeny: a global approach to systems biology (part 2 of 2)

ENDOBIOGENY AND THE BIOLOGY OF FUNCTIONS ARE BASED ON FOUR SCIENTIFIC CONCEPTS THAT ARE KNOWN AND GENERALLY ACCEPTED: (1) human physiology is complex and multifactorial and exhibits the properties of a system; (2) the endocrine system manages metabolism, which is the basis of the continuity of life; (3) the metabolic activity managed by the endocrine system results in the output of biomarkers that reflect the functional achievement of specific aspects of metabolism; and (4) when biomarkers are related to each other in ratios, it contextualizes one type of function relative to another to which is it linked anatomically, sequentially, chronologically, biochemically, etc.

Treatment with thyroid hormone

Thyroid hormone deficiency can have important repercussions. Treatment with thyroid hormone in replacement doses is essential in patients with hypothyroidism. In this review, we critically discuss the thyroid hormone formulations that are available and approaches to correct replacement therapy with thyroid hormone in primary and central hypothyroidism in different periods of life such as pregnancy, birth, infancy, childhood, and adolescence as well as in adult patients, the elderly, and in patients with comorbidities. Despite the frequent and long term use of l-T4, several studies have documented frequent under- and overtreatment during replacement therapy in hypothyroid patients. We assess the factors determining l-T4 requirements (sex, age, gender, menstrual status, body weight, and lean body mass), the major causes of failure to achieve optimal serum TSH levels in undertreated patients (poor patient compliance, timing of l-T4 administration, interferences with absorption, gastrointestinal diseases, and drugs), and the adverse consequences of unintentional TSH suppression in overtreated patients. Opinions differ regarding the treatment of mild thyroid hormone deficiency, and we examine the recent evidence favoring treatment of this condition. New data suggesting that combined therapy with T3 and T4 could be indicated in some patients with hypothyroidism are assessed, and the indications for TSH suppression with l-T4 in patients with euthyroid multinodular goiter and in those with differentiated thyroid cancer are reviewed. Lastly, we address the potential use of thyroid hormones or their analogs in obese patients and in severe cardiac diseases, dyslipidemia, and nonthyroidal illnesses.

The prevalence and prognostic effects of subclinical thyroid dysfunction in dilated cardiomyopathy patients: a single-center cohort study

BACKGROUND

Subclinical thyroid dysfunction may be a risk factor for mortality in patients with heart failure and may be associated with dilated cardiomyopathy (DCM). This was a cohort study to examine the possible association between subclinical thyroid dysfunction and all-cause mortality in DCM patients, because the current evidence on this association remains elusive.

METHODS AND RESULTS

A total of 963 DCM patients were evaluated for thyroid function. Of these patients, 7.1% (n = 68) had subclinical hyperthyroidism (defined as serum thyroid-stimulating hormone [TSH] <0.35 μIU/mL), 84.7% (n = 816) had euthyroidism (TSH 0.35-5.5 μIU/mL), and 8.2% (n = 79) had subclinical hypothyroidism (TSH >5.5 μIU/mL). There was a significant difference in all-cause mortality rates between patients with euthyroidism and patients with subclinical hyper- and hypothyroidism (21%, 38.2%, and 26.6%, respectively; log-rank χ(2) = 13.104; P = .001) with mean follow-up of 3.5 years. After adjustment for other confounding factors at baseline, QRS duration, N-terminal pro-B-type natriuretic peptide, New York Heart Association functional class, left atrial diameter, and subclinical hyperthyroidism (hazard ratio 1.793, 95% CI 1.010-3.183; P = .046) emerged as significant predictors of all-cause mortality.

CONCLUSION

DCM patients with subclinical hyper- and hypothyroidism had higher all-cause mortality rates. However, only subclinical hyperthyroidism, not subclinical hypothyroidism, was an independent predictor for increased risk of all-cause mortality.

Cardiovascular risk and quality of life in elderly people with mild thyroid hormone deficiency

Subclinical hypothyroidism (sHT) is a common condition in the general population, the prevalence increases with age, especially in women. An association between sHT and increased coronary heart disease (CHD) and heart failure (HF) risk and mortality has been described. However, this association is far to be established in older people (>65 years), especially in the oldest old (>85 years). Individuals with sHT may experience symptoms that resemble those observed in the overt form of the disease, leading to an impaired quality of life (QoL). Although very old people are frequently frail and potentially more susceptible to the effects of a disease, few studies were designed to assess the effect of sHT on QoL in this subset of population. Interestingly, the serum TSH concentration curve of general population has a skewed distribution with a "tail" toward higher values, which is amplified with aging. Thus, the diagnosis of sHT and the interpretation of its potential effects on CV function and QoL in older people may be a challenge for the clinician. Giving these premises, we reviewed the English scientific literature available on National Library of Medicine (www.pubmed.com) since 1980 regarding hypothyroidism, sHT, elderly, cardiovascular risk, CHD or HF events and mortality, health-related QoL, and LT4 therapy. Consistent results among large prospective cohort studies suggest an age-independent relationship between sHT and HF progression, while an impact of sHT on CHD events and mortality is essentially reported in young adults (aged below 65-70 years) with long-lasting disease. Scanty data are available on QoL of older people with sHT (>65 years) and, generally, no significant alterations are described.

2013 ETA Guideline: Management of Subclinical Hypothyroidism

Subclinical hypothyroidism (SCH) should be considered in two categories according to the elevation in serum thyroid-stimulating hormone (TSH) level: mildly increased TSH levels (4.0-10.0 mU/l) and more severely increased TSH value (>10 mU/l). An initially raised serum TSH, with FT4 within reference range, should be investigated with a repeat measurement of both serum TSH and FT4, along with thyroid peroxidase antibodies, preferably after a 2- to 3-month interval. Even in the absence of symptoms, replacement therapy with L-thyroxine is recommended for younger patients (<65-70 years) with serum TSH >10 mU/l. In younger SCH patients (serum TSH <10 mU/l) with symptoms suggestive of hypothyroidism, a trial of L-thyroxine replacement therapy should be considered. For such patients who have been started on L-thyroxine for symptoms attributed to SCH, response to treatment should be reviewed 3 or 4 months after a serum TSH within reference range is reached. If there is no improvement in symptoms, L-thyroxine therapy should generally be stopped. Age-specific local reference ranges for serum TSH should be considered in order to establish a diagnosis of SCH in older people. The oldest old subjects (>80-85 years) with elevated serum TSH ≤10 mU/l should be carefully followed with a wait-and-see strategy, generally avoiding hormonal treatment. If the decision is to treat SCH, then oral L-thyroxine, administered daily, is the treatment of choice. The serum TSH should be re-checked 2 months after starting L-thyroxine therapy, and dosage adjustments made accordingly. The aim for most adults should be to reach a stable serum TSH in the lower half of the reference range (0.4-2.5 mU/l). Once patients with SCH are commenced on L-thyroxine treatment, then serum TSH should be monitored at least annually thereafter.