Exercise performance in young and middle-aged female patients with subclinical hyperthyroidism

Treatment of subclinical hypothyroidism: assessing when treatment is likely to be beneficial

Introduction: Subclinical hypothyroidism (SCH) is a common condition diagnosed in up to 16% of the population. SCH is diagnosed when serum TSH is high and circulating thyroid hormones are within the reference range. SCH is considered to be a mild form of thyroid failure by some due to the log-linear relationship between TSH and thyroid hormones. Nevertheless, it is unclear whether the treatment of SCH with thyroid hormones is beneficial, and hence, it is not surprising that expert opinions and recommendations from societies differ in their opinions on how best to manage SCH.Areas covered: This article reviews the currently available evidence pertaining to SCH and provides recommendations as to when treatment of SCH should be considered. An electronic search of PubMed from 1970 to 2019 was performed and systematically reviewed studies assessing the effects of treatment in SCH. The main areas that are considered are the effects of treatment on symptoms and quality of life, and important clinical consequences including psychocognitive outcomes and cardiovascular events.Expert opinion: Treatment of SCH with thyroid hormones is debated and the current literature in this area lacks clarity. We provide an evidence-based recommendation for when treatment of SCH with thyroid hormones should be considered.

Subclinical hypothyroidism and depression: a meta-analysis

The objective of this study was to evaluate the relationship between subclinical hypothyroidism (SCH) and depression. We also analysed the effect of levothyroxine (L-T4) on depression in SCH patients. We found an insignificant difference for the composite endpoint: standard mean difference (SMD) of 0.23 (95% confidence interval (CI) -0.03, 0.48, P = 0.08, I² = 73.6%). The odds ratio (OR) for depressive patients was 1.75 (95% CI 0.97, 3.17 P = 0.064, I² = 64.6%). Furthermore, sub-group analysis according to age found that SCH was related to depression in younger patients (<60 years old), as defined by the diagnosis of depression: OR of 3.8 (95% CI 1.02, 14.18, P = 0.047, I² = 0.0%) or an increase on the depressive scale: SMD of 0.42 (95% CI 0.03, 0.82, P = 0.036, I² = 66.6%). Meanwhile, SCH did not associate with depression in older patients (≥60 years old), as defined by the diagnosis of depression: OR of 1.53 (95% CI 0.81, 2.90, P = 0.193, I² = 71.3%) or an increase on the depressive scale: SMD of 0.03 (95%CI -0.31, 0.37, P = 0.857, I² = 79.8%). We also found an insignificant difference in the composite endpoint between the L-T4 supplementation group and placebo group in SCH patients. The estimated SMD was 0.26 (95% CI -0.09, 0.62, P = 0.143, I² = 52.9%). This meta-analysis demonstrates that SCH is not connected to depression. However, sub-group analysis according to age found that SCH is related to depression in younger patients, but not in older patients. Furthermore, we failed to find an effect of L-T4 supplementation treatment for SCH on depression.

Subclinical Thyroid Dysfunction and Frailty Among Older Men

CONTEXT

Both subclinical thyroid dysfunction and frailty are common among older individuals, but data on the relationship between these 2 conditions are conflicting.

OBJECTIVE

The purpose of this study was to assess the cross-sectional and prospective associations between subclinical thyroid dysfunction and frailty and the 5 frailty subdomains (sarcopenia, weakness, slowness, exhaustion, and low activity).

SETTING AND DESIGN

The Osteoporotic Fractures in Men Study is a prospective cohort study.

PARTICIPANTS

Men older than 65 years (n = 1455) were classified into 3 groups of thyroid status: subclinical hyperthyroidism (n = 26, 1.8%), subclinical hypothyroidism (n = 102, 7.0%), and euthyroidism (n = 1327, 91.2%).

MAIN OUTCOME MEASURES

Frailty was defined using a slightly modified Cardiovascular Health Study Index: men with 3 or more criteria were considered frail, men with 1 to 2 criteria were considered intermediately frail, and men with no criteria were considered robust. We assessed the cross-sectional relationship between baseline thyroid function and the 3 categories of frailty status (robust/intermediate/frail) as well as the prospective association between baseline thyroid function and subsequent frailty status and mortality after a 5-year follow-up.

RESULTS

At baseline, compared with euthyroid participants, men with subclinical hyperthyroidism had an increased likelihood of greater frailty status (adjusted odds ratio, 2.48; 95% confidence interval, 1.15-5.34), particularly among men aged <74 years at baseline (odds ratio for frailty, 3.63; 95% confidence interval, 1.21-10.88). After 5 years of follow-up, baseline subclinical hypothyroidism and hyperthyroidism were not consistently associated with overall frailty status or frailty components.

CONCLUSION

Among community-dwelling older men, subclinical hyperthyroidism, but not subclinical hypothyroidism, is associated with increased odds of prevalent but not incident frailty.

Does low serum TSH within the normal range have negative impact on physical exercise capacity and quality of life of healthy elderly people?

OBJECTIVE

Investigate the differences in cardiopulmonary (CP) capacity and Quality of Life (QOL) between healthy elderly (≥ 65 years) with different TSH levels (< 1.0 and ≥ 1.0 μIU/mL) both within the normal range. Also, evaluate the effects of TSH elevation on CP test and QOL, by administering methimazole to subjects with initial lower-normal TSH, in order to elevate it to superior-normal limit.

MATERIALS AND METHODS

Initially, a cross-sectional study was performed to compare CP capacity at peak exercise and QOL (using WHOQOL-OLD questionnaire) between healthy seniors (age ≥ 65 years) with TSH < 1.0 μIU/mL vs. TSH ≥1.0 μIU/mL. In the second phase, participants with TSH < 1.0 μIU/mL were included in a non-controlled-prospective-interventional study to investigate the effect of TSH elevation, using methimazole, on QOL and CP capacity at peak exercise.

RESULTS

From 89 elderly evaluated, 75 had TSH ≥ 1 μIU/mL and 14 TSH < 1 μIU/mL. The two groups had similar basal clinical characteristics. No difference in WHOQOL-OLD scores was observed between groups and they did not differ in terms of CP function at peak exercise. QOL and CP variables were not correlated with TSH levels. Twelve of 14 participants with TSH < 1.0 μIU/mL entered in the prospective study. After one year, no significant differences in clinical caracteristics, QOL, and CP variables were detected in paired analysis before and after methimazole intervention.

CONCLUSIONS

We found no differences in CP capacity and QOL between health elderly with different TSH levels within normal range and no impact after one year of methimazole treatment. More prospective-controlled-randomized studies are necessary to confirm or not the possible harm effect in normal low TSH.

A systematic review of randomized controlled trials for management of persistent post-treatment fatigue in thyroid cancer survivors

BACKGROUND

Fatigue that persists post-treatment is commonly reported by thyroid cancer (TC) survivors.

METHODS

A systematic review of published English language randomized controlled trials (RCTs) on interventions for management of persistent post-treatment fatigue in TC was conducted. This review excluded studies on short-term interventions used in preparation for radioactive iodine diagnostic scans or treatment. An electronic search was executed in six databases and supplemented by a hand search. Two reviewers independently reviewed all citations from the electronic search and relevant full-text studies. Two abstractors independently critically appraised included studies and abstracted the data. The data were qualitatively summarized.

RESULTS

A total of 1086 unique citations and 25 full-text studies were reviewed. Four studies summarizing the results of three RCTs were included. The interventions included: combination triiodothyronine with levothyroxine (L-T4) therapy compared to L-T4 alone (one RCT), reduction in degree of thyrotropin (TSH) suppression using L-T4 compared to maintenance of TSH suppression (one RCT), and supervised exercise compared to inactivity (two RCTs examining different fatigue outcomes in same population). Trial duration ranged from 10 weeks to six months. All trials had limitations, and the number of TC survivors included in respective RCTs ranged from 15 to 36. Hormonal treatment RCTs had mixed fatigue outcome results within respective trials. However, multiple measures suggesting improvement in fatigue were reported following the exercise intervention.

CONCLUSIONS

There is paucity of RCTs to guide evidence-based management of persistent post-treatment fatigue in TC survivors. RCTs of interventions for prevention or treatment of fatigue in TC survivors are needed.

Depressive symptoms in patients with subclinical hypothyroidism--the effect of treatment with levothyroxine: a double-blind randomized clinical trial

Despite the increasing evidence for relationships between thyroid dysfunction and neuropsychiatric alterations, the effect of treatment of thyroid disease on various clinical psychiatric outcomes is controversial. The purpose of this study was to investigate the effect of levothyroxine treatment on depressive symptoms in subjects with subclinical hypothyroidism. A randomized double-blind placebo-controlled clinical trial was performed. Sixty subjects (51 females and 9 males) with subclinical hypothyroidism were enrolled. Beck Depression Inventory was completed for all participants at the beginning of the study and 12 weeks after enrollment. The intervention and control groups received levothyroxine and placebo, respectively, for 12 weeks. There were no statistical differences in the total depression score and its subscales between the two groups at the beginning of the study. The Beck Depression Inventory score decreased from 16.79 ± 13.25 to 12.37 ± 10.01 (p value = 0.04) in the intervention group. The change in score was not significant for the control group (13.77 ± 11.71 to 11.86 ± 10.71; p value= 0.16). The affective subscale of Beck Depression Inventory did not change after 12 weeks of treatment with levothyroxine, while somatic subscale remarkably improved in the intervention group (p value = 0.02). This study showed the efficacy of treatment of subclinical hypothyroidism in people with levothyroxine in relation to depressive symptoms.

Serum thyroid-stimulating hormone levels are not associated with exercise capacity and lung function parameters in two population-based studies

BACKGROUND

Thyroid dysfunction has been described to be linked to a variety of cardiovascular morbidities. Through this pathway thyroid function might also be associated with cardiorespiratory function and exercise capacity. So far only few patient-studies with small study populations investigated the association between thyroid dysfunction and exercise capacity. Thus, the aim of our study was to investigate the association of serum thyroid-stimulating hormone (TSH) levels with lung function and cardiopulmonary exercise testing (CPET) in the general population.

METHODS

Data from the two independent cross-sectional population-based studies (Study of Health in Pomerania [SHIP] and SHIP-Trend-0) were pooled. SHIP was conducted between 2002 and 2006 and SHIP-Trend-0 between 2008 and 2012. Participants were randomly selected from population registries. In total, 4206 individuals with complete data were available for the present analysis. Thyroid function was defined based on serum TSH levels. Lung function was evaluated by forced expiratory volume in 1 s and forced vital capacity. CPET was based on symptom limited exercise tests on a bicycle in a sitting position according to a modified Jones protocol. Associations of serum TSH levels with lung function and CPET parameters were analysed by multivariable quantile regression adjusted for age, sex, height, weight, use of beta blockers, smoking status, and physical activity.

RESULTS

Serum TSH levels, used as continuously distributed variable and categorized according to the clinical cut-offs 0.3 and 3.0 mIU/L or according to quintiles, were not consistently associated with parameters of lung function or CPET.

CONCLUSIONS

Our results suggest that thyroid dysfunction is not associated with lung function and cardiopulmonary exercise capacity in the general population.

Subclinical Thyroid Disorders: Clinical Significance and When to Treat?

Subclinical thyroid disorders are commonly encountered in the primary care setting. This article aims to review the latest evidence and guidelines pertaining to the management of subclinical hypo- and hyperthyroidism, in particular the important decision of when treatment should be considered.

Subclinical thyroid dysfunction and functional capacity among elderly

BACKGROUND

Subclinical thyroid dysfunction is common among older people and has been associated with decreased functional capacity but with conflicting data. The aim of this study was to assess the association between subclinical thyroid dysfunction and functional capacity in an elderly population.

METHODS

We included 5182 participants with a mean age of 75.2 years from the Prospective Study of Pravastatin in the Elderly at Risk (PROSPER). Self-reported functional capacity was assessed using the Barthel Index (BI) and the Instrumental Activities of Daily Living (IADL) scores at baseline and during follow-up. Participants with subclinical hyperthyroidism (n=65) and subclinical hypothyroidism (n=173) were compared to euthyroid participants (n=4944). The association between persistent subclinical thyroid dysfunction and functional capacity and decline was also investigated.

RESULTS

At baseline, compared to euthyroid participants (BI 19.73±SE 0.06; IADL 13.52±0.02), there was no difference in functional capacity for participants with subclinical hyperthyroidism (BI 19.60±0.09; IADL 13.51±0.12, p>0.05) or subclinical hypothyroidism (BI 19.82±0.06; IADL 13.55±0.08, p>0.05). Over a mean 3.2-year follow-up period, there was no association between thyroid function and annual decline of either BI or IADL (p>0.05). No association was found between persistent subclinical thyroid dysfunction and functional capacity at baseline or during follow-up (p>0.05). Results were similar after excluding participants with a maximum BI and/or IADL score at baseline.

CONCLUSION

Among well-functioning community-dwelling elderly, we found no evidence that subclinical thyroid dysfunction contributes to decreased functional capacity.

Impaired functional and hemodynamic response to graded exercise testing and its recovery in patients with subclinical hyperthyroidism

OBJECTIVE

To evaluate the functional and hemodynamic responses during exercise and its recovery in patients with subclinical hyperthyroidism (SCH).

SUBJECTS AND METHODS

A cross-sectional study was carried out with 29 patients on TSH-suppressive therapy with levothyroxine for thyroid carcinoma and 35 euthyroid subjects. All volunteers underwent a cardiopulmonary exercise testing on a treadmill and functional and hemodynamic variables were measured during exercise and its recovery.

RESULTS

SCH patients showed impaired functional response to exercise, marked by lower values for oxygen consumption and exercise duration in addition to premature achievement of the anaerobic threshold. Heart-rate and blood pressure recovery immediately after exercise were slower among SCH patients when compared to euthyroid subjects.

CONCLUSION

SCH is associated with impaired functional and hemodynamic responses during exercise and its recovery.

Endogenous subclinical thyroid disorders, physical and cognitive function, depression, and mortality in older individuals

OBJECTIVE

To what extent endogenous subclinical thyroid disorders contribute to impaired physical and cognitive function, depression, and mortality in older individuals remains a matter of debate.

DESIGN

A population-based, prospective cohort of the Longitudinal Aging Study Amsterdam.

METHODS

TSH and, if necessary, thyroxine and triiodothyronine levels were measured in individuals aged 65 years or older. Participants were classified according to clinical categories of thyroid function. Participants with overt thyroid disease or use of thyroid medication were excluded, leaving 1219 participants for analyses. Outcome measures were physical and cognitive function, depressive symptoms (cross-sectional), and mortality (longitudinal)

RESULTS

Sixty-four (5.3%) individuals had subclinical hypothyroidism and 34 (2.8%) individuals had subclinical hyperthyroidism. Compared with euthyroidism (n=1121), subclinical hypo-, and hyper-thyroidism were not significantly associated with impairment of physical or cognitive function, or depression. On the contrary, participants with subclinical hypothyroidism did less often report more than one activity limitation (odds ratio 0.44, 95% confidence interval (CI) 0.22-0.86). After a median follow-up of 10.7 years, 601 participants were deceased. Subclinical hypo- and hyper-thyroidism were not associated with increased overall mortality risk (hazard ratio 0.89, 95% CI 0.59-1.35 and 0.69, 95% CI 0.40-1.20 respectively).

CONCLUSIONS

This study does not support disadvantageous effects of subclinical thyroid disorders on physical or cognitive function, depression, or mortality in an older population.

Benefits of thyrotropin suppression versus the risks of adverse effects in differentiated thyroid cancer

BACKGROUND

Despite clinical practice guidelines for the management of differentiated thyroid cancer (DTC), there are no recommendations on the optimal serum thyrotropin (TSH) concentration to reduce tumor recurrences and improve survival, while ensuring an optimal quality of life with minimal adverse effects. The aim of this review was to provide a risk-adapted management scheme for levothyroxine (L-T4) therapy in patients with DTC. The objective was to establish which patients require complete suppression of serum TSH levels, given their risk of recurrent or metastatic DTC, and how potential adverse effects on the heart and skeleton, induced by subclinical hyperthyroidism, in concert with advanced age and comorbidities, may influence the degree of TSH suppression.

SUMMARY

A risk-stratified approach to predict the rate of recurrence and death from thyroid cancer was based on the recently revised American Thyroid Association guidelines. A stratified approach to predict the risk from the adverse effects of L-T4 was devised, taking into account the age of the patient, as well as the presence of preexisting cardiovascular and skeletal risk factors that might predispose to the development of long-term adverse cardiovascular or skeletal outcomes, particularly increased heart rate and left ventricular mass, atrial fibrillation, and osteoporosis. Nine potential patient categories can be defined, with differing TSH targets for both initial and long-term L-T4 therapy.

CONCLUSION

Before deciding on the degree of TSH suppression during initial and long-term L-T4 treatment in patients with DTC, it is necessary to consider the aggressiveness of DTC, as well as the potential for adverse effects induced by iatrogenic subclinical hyperthyroidism. More aggressive TSH suppression is indicated in patients with high-risk disease or recurrent tumor, whereas less aggressive TSH suppression is reasonable in low-risk patients. In patients with high-risk DTC and an equally high risk of adverse effects, long-term treatment with L-T4 therapy should be individualized and balanced against the potential for adverse effects. In patients with an intermediate risk for thyroid cancer recurrence and a high risk of adverse effects of therapy, the degree of TSH suppression should be reevaluated during the follow-up period. Normalization of serum TSH is advisable for long-term treatment of disease-free elderly patients with DTC and significant comorbidities.

The clinical significance of subclinical thyroid dysfunction

Subclinical thyroid disease (SCTD) is defined as serum free T(4) and free T(3) levels within their respective reference ranges in the presence of abnormal serum TSH levels. SCTD is being diagnosed more frequently in clinical practice in young and middle-aged people as well as in the elderly. However, the clinical significance of subclinical thyroid dysfunction is much debated. Subclinical hyper- and hypothyroidism can have repercussions on the cardiovascular system and bone, as well as on other organs and systems. However, the treatment and management of SCTD and population screening are controversial despite the potential risk of progression to overt disease, and there is no consensus on the thyroid hormone and thyrotropin cutoff values at which treatment should be contemplated. Opinions differ regarding tissue effects, symptoms, signs, and cardiovascular risk. Here, we critically review the data on the prevalence and progression of SCTD, its tissue effects, and its prognostic implications. We also examine the mechanisms underlying tissue alterations in SCTD and the effects of replacement therapy on progression and tissue parameters. Lastly, we address the issue of the need to treat slight thyroid hormone deficiency or excess in relation to the patient's age.

Altered cardiovascular vagal responses in nonelderly female patients with subclinical hyperthyroidism and no apparent cardiovascular disease

OBJECTIVE

Subclinical hyperthyroidism (SH) has been associated with exercise intolerance, changes in cardiac morphology, atrial arrhythmias and sympathovagal imbalance. The aim of this study was to evaluate the vagal reserve and modulation by a sympathetic stimulus in nonelderly patients with SH without cardiovascular problems.

DESIGN

We carried out a cross-sectional study, comparing data of the heart rate variability (HRV) of SH patients and healthy controls at rest and after vagal and sympathetic stimulation.

PATIENTS

We studied 16 female patients with at least 6 months of SH and 16 healthy female controls with the same median age (40 vs. 34.5 years).

MEASUREMENTS

We used the tilt test, with electrocardiographic record at rest, during the respiratory sinus arrhythmia (RSA) manoeuvre and after tilting, in order to analyse HRV in the frequency domain (%high frequency (HF) and low/high frequency ratio (LF/HF) using Biopotentials Captation System software.

RESULTS

The median TSH level was 0.03 mU/l in patients and 1.37 mUI/l in controls. The median free T4 was 1.37 ng/dl in patients and 1.20 ng/dl in controls. Patients demonstrated a significantly smaller difference between %HF during the RSA and %HF at rest than controls (median -7.5 vs. 36.6, P < 0.001). There was a lower difference between LF/HF ratio after tilting and LF/HF ratio at rest in patients than in controls (1.5 vs. 5.3, P = 0.005).

CONCLUSION

Subclinical hyperthyroidism affects cardiovascular autonomic balance in otherwise apparently healthy nonelderly females by blunting vagal responses.