Should we reconsider blocking the thyroid for 123 I-Ioflupane studies in elderly patients: quantifying radiation dose to the unblocked thyroid and implications for clinical practice

OBJECTIVES

To measure the absorbed dose to the thyroid in patients injected with 123 I-Ioflupane where the thyroid was not blocked with prophylaxis to investigate whether thyroid blocking should be limited to younger patients. This risk from the additional absorbed dose to the thyroid was then compared to the risk from iodine overdose through ingestion of the iodide prophylaxis, resulting in iodine-induced hyper/hypothyroidism (IIH).

METHODS

A cohort of patients (n = 30) who did not receive thyroid prophylaxis underwent static thyroid imaging 3 h after 123 I-Ioflupane administration. The measured thyroidal uptake of free 123 I was then extrapolated to peak uptake time (24 h post-administration). This value was used to calculate cumulated activity in the thyroid and thus thyroid-thyroid absorbed dose D(rthy←rthy ) using the relevant S-value in the MIRD method.

RESULTS

Mean D(rthy←rthy ) was found to be 13.6 mGy with an SD of 8.8 mGy; this would contribute an additional 0.5 mSv to the effective dose.

CONCLUSION

ARSAC recommends in its Notes for Guidance prophylactic thyroid blocking if the absorbed dose to the thyroid is >50 mGy; the maximum thyroid dose in this study cohort was 36.3 mGy. With risk from IIH and its associated cardiac complications increasing with age, this study suggests that iodide prophylaxis with 123 I-Ioflupane should be reconsidered for elderly patient.

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

BACKGROUND

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

METHODS

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

DISCUSSION

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

TRIAL REGISTRATION

Not applicable.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

None.

The GLP-1 receptor agonist exenatide reduces serum TSH by its effect on body weight in people with type 2 diabetes

OBJECTIVE

Glucagon-like peptide-1 receptor agonist (GLP-1 RA) therapy in patients with type 2 diabetes and obesity leads to a significant reduction in serum thyrotropin (TSH) levels but it is unclear whether this is related to weight loss and improvement in sensitivity to thyroid hormones (TH).

DESIGN, PATIENTS AND MEASUREMENTS

We prospectively analysed clinical and biochemical data in patients with type 2 diabetes and obesity who were commenced on the GLP-1 RA exenatide and followed them for 12 months. We assessed the relationship between changes in body weight and serum TSH and resistance to TH indices.

RESULTS

In 112 patients (mean age: 53.5 years, 43.8% female, mean body mass index: 39.8 kg/m2 ), 12 months of exenatide treatment was associated with a mean (95% CI) percent body weight loss of 6.5% (5.0%-8.1%) and change in serum TSH of -0.25 mU/L (-0.43 to -0.06). There was a significant negative and nonlinear relationship between change in serum TSH and percent body weight loss: -0.25 mU/L with 5%, -0.4 mU/L with 10% and -0.5 mU/L with 15%, respectively, whereas a rise in serum TSH of 0.5 mU/L was associated with 5% weight gain. There were no changes observed in serum FT4 levels with weight loss but a significant reduction in resistance to TH indices was noted.

CONCLUSIONS

Exenatide therapy reduces serum TSH levels and improves central sensitivity to TH action over 12 months via its effect on weight loss. The effectiveness of weight loss strategies, rather than TH replacement, should be investigated in individuals with obesity and mildly raised serum TSH levels.

Expansion of the immature B lymphocyte compartment in Graves' disease

OBJECTIVE

The specific mechanisms driving autoimmunity in Graves' disease (GD) remain largely unknown. Kappa-deleting recombination excision circles (KRECs) are circular DNA molecules generated during B cell maturation in the bone marrow which provide a measure of B cell production and proliferation. We aimed to investigate the association between KRECs and B cell subpopulations, with thyroid status and clinical outcome in GD patients.

METHODS

Kappa-deleting recombination excision circles were measured by quantitative real-time PCR using a triple-insert plasmid control in 132 GD patients and 140 healthy controls. In addition, KRECs in GD patients on withdrawal of antithyroid drug (ATD) and 6-10 weeks later were analysed according to a clinical outcome at 1 year. Flow cytometry was performed on isolated CD19+ B cells to quantitate 7 B lymphocyte subpopulations in 65 GD patients.

RESULTS

Circulating KRECs were higher in GD vs. controls (P = 1.5 × 10-9) and demonstrated a positive correlation to thyroid hormones and autoantibodies (free thyroxine: P = 2.14 × 10-5, rho = .30; free triiodothyronine: P = 1.99 × 10-7, rho = .37; thyroid stimulating hormone receptor autoantibodies: P = 1.36 × 10-5, rho = .23). Higher KRECs in GD patients 6-10 weeks after ATD withdrawal were associated with relapse of hyperthyroidism at 1 year (P = .04). The KRECs were positively correlated to the total CD19+ B cell count (P = 3.2 × 10-7).

CONCLUSIONS

This study reports a robust association between KRECs and GD, highlighting the importance of B cells in the pathogenesis of GD and the influence of thyroid status on B cell activity. The findings indicate a potential role for KRECs as a marker of disease activity and outcome in GD.

Inter-observer Variability of Clinical Activity Score: Assessments in Patients With Thyroid Eye Disease

PURPOSE

Thyroid eye disease (TED) can be difficult to manage. The range of available treatments is expanding rapidly; however, cost is a concern and some patients do not respond. The Clinical Activity Score (CAS) was devised as a measure of disease activity and a potential predictor of response to anti-inflammatory treatment. Despite the widespread use of the CAS, inter-observer variability has not been investigated. The aim of the study was to determine the inter-observer variability of the CAS in patients with TED.

DESIGN

Prospective reliability analysis.

METHODS

Nine patients with a spectrum of clinical features of TED were assessed by 6 experienced observers on the same day. Agreement among the observers was analyzed using the Krippendorff alpha.

RESULTS

The Krippendorff alpha for the total CAS was 0.532 (95% CI = 0.199-0.665), whereas alpha values for the individual components of the CAS varied between 0.171 (CI = 0.000-0.334) for lid redness and 0.671 (CI = 0.294-1.000) for spontaneous pain. Assuming that a CAS value ≥3 implies suitability of the patient for anti-inflammatory treatment, the calculated Krippendorff alpha for agreement among assessors on whether treatment should be given or not given was 0.332 (95% CI = 0.0011-0.5862).

CONCLUSIONS

This study has shown unreliable inter-observer variability in total CAS and most individual CAS components, thus highlighting the need for improving the performance of the CAS or seeking other methods to assess activity.

Treating subclinical hypothyroidism in individuals with or without mental health problems -A Delphi based expert consensus study in two countries

Background

Subclinical hypothyroidism (SCH) is a common endocrine problem with prevalence estimates between 4% and 20%. Symptoms are often non-specific but can substantially affect well-being leading to repeated medical consultations. The effect of thyroid hormone replacement therapy (THRT) in patients with SCH remains uncertain. Current guidelines, limited by the lack of high-quality evidence, have been controversial with limited adherence in clinical practice.

Methods

Three-round modified Delphi method to establish consensus regarding diagnosis and treatment of individuals with SCH with and without affective disorder or anxiety, conducted with clinicians from three specialties, general practice, endocrinology and psychiatry, and two countries, Sweden and the United Kingdom.

Results

Sixty clinicians, 20 per specialty, were recruited. Fifty-three (88%) participants completed all three rounds. The participants reached consensus on five of the 26 practice statements that (a) repeated testing was required for the diagnosis of subclinical hypothyroidism, (b) antibody screening should usually occur, and (c and d) antibody screening would strengthen the indication for thyroid hormone replacement therapy in both individuals with or without affective disorder or anxiety. The participants disagreed with (e) a requirement of a TSH threshold ≥ 20 mIU/L for thyroid hormone replacement therapy start. Psychiatrists and GPs but not endocrinologists, agreed that there was a frequent discrepancy between laboratory results and clinical symptoms, and disagreed that testing for thyroid dysfunction was overused in patients presenting with depression or anxiety, or fatigue.

Conclusions

In many aspects, attitudes toward diagnosing and treating SCH remain diverse. The inability of our Delphi panel to achieve consensus on most items and the disagreement with a TSH ≥ 20 mIU/L threshold for treatment suggest that the concept of SCH may need rethinking with a better understanding of the hypothalamic-pituitary-thyroid physiology. Given that the scientific evidence is currently not conclusive, guidelines in this area should not be taken as definitive.

Subclinical hypothyroidism, outcomes and management guidelines: a narrative review and update of recent literature

Subclinical hypothyroidism (SCH) is diagnosed when serum thyroid stimulation hormone (thyrotropin; TSH) levels are above the reference range, accompanied by levels of free thyroxine within its reference range. The management of SCH remains a diagnostic and therapeutic challenge despite many years of research relating to its epidemiology, aetiology, effectiveness of treatment and safety. European Thyroid Association (ETA) guidelines for the management of SCH were published almost a decade ago. This narrative review summarizes the clinical literature relating to SCH and outcomes since the publication of these guidelines. Clinical evidence emerging during the previous decade generally supports the view that SCH is associated with adverse outcomes to an extent that is intermediate between euthyroidism and overt hypothyroidism although evidence that treatment with thyroid hormone replacement is beneficial is lacking. Accordingly, the rationale for the recommendations for intervention in the ETA guidelines based on the age of the patient, level of serum TSH, symptoms and comorbidities remains valid today.

Variation in the reference range limits of thyroid function tests and association with the prevalence of levothyroxine treatment

Many individuals with marginally abnormal thyroid function test (TFT) results may be treated and it is unknown if the limits of the thyrotropin (TSH) and free thyroxine (FT4) reference intervals reported alongside the laboratory results are associated with the prevalence of levothyroxine treatment. We obtained information regarding reported TFT reference intervals from UK National Health Service (NHS) laboratories and evaluated its relationship with the prevalence of levothyroxine treatment for corresponding health areas for 2014. The upper limit of serum TSH was significantly, linearly, independently, and negatively associated with prevalent levothyroxine treatment: -0.54% (95% CI, -0.68% to -0.40%). The lower limit of serum FT4 was significantly and independently associated with the prevalence of levothyroxine treatment in a non-linear (J-shaped) manner with an increase being noted from a FT4 level of ≈9.5 pmol/L onwards. We conclude that minor changes in the reference range limits for serum TSH and FT4 are associated with levothyroxine treatment.

Replication of association at the LPP and UBASH3A loci in a UK autoimmune Addison's disease cohort

Autoimmune Addison's disease (AAD) arises from a complex interplay between multiple genetic susceptibility polymorphisms and environmental factors. The first genome wide association study (GWAS) with patients from Scandinavian Addison's registries has identified association signals at four novel loci in the genes LPP, SH2B3, SIGLEC5, and UBASH3A. To verify these novel risk loci, we performed a case-control association study in our independent cohort of 420 patients with AAD from the across the UK. We report significant association of alleles of the LPP and UBASH3A genes [odds ratio (95% confidence intervals), 1.46 (1.21-1.75)and 1.40 (1.16-1.68), respectively] with AAD in our UK cohort. In addition, we report nominal association of AAD with SH2B3 [OR 1.18 (1.02-1.35)]. We confirm that variants at the LPP and UBASH3A loci confer susceptibility to AAD in a UK population. Further studies with larger patient cohorts are required to robustly confirm the association of SH2B3 and SIGLEC5/SPACA6 alleles.

Subclinical thyroid dysfunction and incident diabetes: a systematic review and an individual participant data analysis of prospective cohort studies

OBJECTIVE

Few prospective studies have assessed whether individuals with subclinical thyroid dysfunction are more likely to develop diabetes, with conflicting results. In this study, we conducted a systematic review of the literature and an individual participant data analysis of multiple prospective cohorts to investigate the association between subclinical thyroid dysfunction and incident diabetes.

METHODS

We performed a systematic review of the literature in Medline, Embase, and the Cochrane Library from inception to February 11, 2022. A two-stage individual participant data analysis was conducted to compare participants with subclinical hypothyroidism and subclinical hyperthyroidism vs euthyroidism at baseline and the adjusted risk of developing diabetes at follow-up.

RESULTS

Among 61 178 adults from 18 studies, 49% were females, mean age was 58 years, and mean follow-up time was 8.2 years. At the last available follow-up, there was no association between subclinical hypothyroidism and incidence of diabetes (odds ratio (OR) = 1.02, 95% CI: 0.88-1.17, I2 = 0%) or subclinical hyperthyroidism and incidence of diabetes (OR = 1.03, 95% CI: 0.82-1.30, I2 = 0%), in age- and sex-adjusted analyses. Time-to-event analysis showed similar results (hazard ratio for subclinical hypothyroidism: 0.98, 95% CI: 0.87-1.11; hazard ratio for subclinical hyperthyroidism: 1.07, 95% CI: 0.88-1.29). The results were robust in all sub-group and sensitivity analyses.

CONCLUSIONS

This is the largest systematic review and individual participant data analysis to date investigating the prospective association between subclinical thyroid dysfunction and diabetes. We did not find an association between subclinical thyroid dysfunction and incident diabetes. Our results do not support screening patients with subclinical thyroid dysfunction for diabetes.

SIGNIFICANCE STATEMENT

Evidence is conflicting regarding whether an association exists between subclinical thyroid dysfunction and incident diabetes. We therefore aimed to investigate whether individuals with subclinical thyroid dysfunction are more prone to develop diabetes in the long run as compared to euthyroid individuals. We included data from 18 international cohort studies with 61 178 adults and a mean follow-up time of 8.2 years. We did not find an association between subclinical hypothyroidism or subclinical hyperthyroidism at baseline and incident diabetes at follow-up. Our results have clinical implications as they neither support screening patients with subclinical thyroid dysfunction for diabetes nor treating them in the hope of preventing diabetes in the future.

Postradioiodine Graves' management: The PRAGMA study

OBJECTIVE

Thyroid status in the months following radioiodine (RI) treatment for Graves' disease can be unstable. Our objective was to quantify frequency of abnormal thyroid function post-RI and compare effectiveness of common management strategies.

DESIGN

Retrospective, multicentre and observational study.

PATIENTS

Adult patients with Graves' disease treated with RI with 12 months' follow-up.

MEASUREMENTS

Euthyroidism was defined as both serum thyrotropin (thyroid-stimulating hormone [TSH]) and free thyroxine (FT4) within their reference ranges or, when only one was available, it was within its reference range; hypothyroidism as TSH ≥ 10 mU/L, or subnormal FT4 regardless of TSH; hyperthyroidism as TSH below and FT4 above their reference ranges; dysthyroidism as the sum of hypo- and hyperthyroidism; subclinical hypothyroidism as normal FT4 and TSH between the upper limit of normal and <10 mU/L; and subclinical hyperthyroidism as low TSH and normal FT4.

RESULTS

Of 812 patients studied post-RI, hypothyroidism occurred in 80.7% and hyperthyroidism in 48.6% of patients. Three principal post-RI management strategies were employed: (a) antithyroid drugs alone, (b) levothyroxine alone, and (c) combination of the two. Differences among these were small. Adherence to national guidelines regarding monitoring thyroid function in the first 6 months was low (21.4%-28.7%). No negative outcomes (new-onset/exacerbation of Graves' orbitopathy, weight gain, and cardiovascular events) were associated with dysthyroidism. There were significant differences in demographics, clinical practice, and thyroid status postradioiodine between centres.

CONCLUSIONS

Dysthyroidism in the 12 months post-RI was common. Differences between post-RI strategies were small, suggesting these interventions alone are unlikely to address the high frequency of dysthyroidism.

Getting the levothyroxine (LT4) dose right for adults with hypothyroidism: opportunities and challenges in the use of modern LT4 preparations

Lifelong treatment with levothyroxine (LT4) is the mainstay of management for individuals with hypothyroidism. Many hypothyroid patients start LT4 treatment at a low dose (e.g. 25-50 µg), especially the elderly, those with residual thyroid function, those with low body weight, and those with significant (especially cardiac) comorbidities. Almost half of patients on LT4 replacement therapy demonstrate either under- or over-treatment. Many LT4 preparations have relatively large intervals between tablet strengths at the lower end of their dose ranges (providing 25 µg, 50 µg, and 75 µg tablets), which may represent a barrier to achieving the optimum maintenance treatment for some patients. The availability of intermediate tablet strengths of LT4 in the 25-75 µg range may facilitate precise and effective dose titration of LT4 and may also enable convenient maintenance regimens based on a single LT4 tablet daily, to support adherence to therapy.

Efficacy and Safety of Triiodothyronine Treatment in Cardiac Surgery or Cardiovascular Diseases: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Low levels of the active thyroid hormone triiodothyronine (T3) in cardiac patients are associated with worse outcomes. The aim of this analysis was to assess if T3 treatment is beneficial and safe in patients undergoing cardiac surgery or those with cardiovascular diseases in whom there is observed or expected reduction in serum T3 levels. Methods: A systematic review and meta-analysis of randomized controlled trials (RCTs) was performed as per the PRISMA guidelines. Pubmed, EMBASE, and Web of Science databases were searched for RCTs published between January 1, 1960 and March 30, 2022 that evaluated the effects of T3 therapy in patients undergoing cardiac surgery or with cardiovascular diseases. The primary outcomes were measures of cardiac function. Weighted mean difference (MD) or relative risk was calculated using a random effects model. PROSPERO registration number CRD42020211966. Results: Of the 3181 full-text articles screened, 34 studies with 2547 participants (number ranging between 13 and 223, mean ages between 0.5 and 73 years, mean percentage of women between 7% and 64%) were included. In 12 RCTs with 1093 adults undergoing cardiac surgery T3 therapy was associated with improvement in cardiac index (MD [95% confidence interval], 0.24 [0.08 to 0.40] L/min/m², I² = 74%). The quality of evidence was high to moderate. In 3 RCTs with 188 children undergoing cardiac surgery, 3 RCTs with 131 adult cardiac donors, 3 RCTs with 83 adult patients with heart failure, and 2 RCTs with 89 adults with acute myocardial infarction, T3 therapy did not improve cardiac index or left ventricular function; the quality of evidence ranged from high (pediatric cardiac surgery) to low (other groups). No detrimental effect of T3 therapy was observed on heart rate, risk of in-hospital atrial fibrillation, or mortality. Conclusions: Short-term T3 therapy is safe and trials in adults undergoing cardiac surgical procedures to evaluate longer term clinical endpoints are required. Current data do not support the routine use of T3 therapy in children undergoing cardiac surgery or in cardiac donors. Adequately designed trials are required to determine if T3 therapy improves cardiac function and clinical outcomes in patients with heart failure or acute myocardial infarction.

The prevalence and significance of nonuniform thyroid radio-isotope uptake in patients with Graves' disease

OBJECTIVE

To evaluate the prevalence and clinical significance of nonuniform technetium (^99m Tc) uptake among patients with Graves' disease (GD).

DESIGN, PATIENTS AND MEASUREMENTS

Patients with GD, referred between July 2005 and March 2018, had Tc⁹⁹ - uptake scans and TSH-receptor antibody (TRAb) measured before antithyroid drug (ATD) therapy. Risk of relapse after ATD cessation was monitored until June 2021 and compared between GD patients based on uptake patterns.

RESULTS

Of the 276 GD patients (mean age, 49.8 years; 84% female), 25 (9.0%) had nonuniform Tc⁹⁹ uptake. At diagnosis, individuals with nonuniform uptake were older (mean age of 61.8 vs. 48.5 years, p < .001), had lower mean thyroid hormone levels (free thyroxine: 36.3 vs. 45.4  pmol/L, p = .04 and free triiodothyronine: 10.0 vs. 17.8 pmol/L, p < .001) and median TRAb levels (4.2 vs. 6.6 U/L, p = .04) compared with those with a uniform uptake. Older age was a significant predictor for the presence of nonuniform uptake in GD patients; odds ratio (95% confidence intervals) of 1.07 (1.03 - 1.10). The risk of relapse was similar in both groups after a median (IQR) follow-up of 41 (13-74) months after ATD cessation (56.0% vs. 46.3%, respectively); hazard ratio (95% confidence intervals) of 1.74 (0.96-3.15).

CONCLUSIONS

Nonuniform radio-isotope uptake is seen in 1 in 11 patients with GD which could be misdiagnosed as toxic multinodular goitre if TRAb levels are not measured. Treatment of GD patients with nonuniform radio-isotope uptake with ATD therapy as first-line appears to be equally effective as compared with those with uniform uptake. TRAb testing should be the main diagnostic test for patients with suspected GD with radio-labelled uptake scans being reserved for those who are TRAb negative.

Frequency, determinants and costs of thyroid function testing in a laboratory serving a large population

OBJECTIVE

To assess the rationale and frequency of thyroid function testing and to analyse factors that influence serum thyrotropin (TSH) levels.

PATIENTS, DESIGN AND MAIN OUTCOME MEASURES

Serum TSH levels were evaluated in a hospital laboratory serving a population of 604 000 in 2018. Patients on medications or with conditions affecting thyroid function were excluded. Frequency of thyroid function testing by age and sex was assessed and the relationship between serum TSH with potential predictor variables was analysed using ordinary least square regression analysis allowing for potential non-linearity.

RESULTS

Twenty-eight percent of the local population had their thyroid function tested at least once in 2018 with significant differences by sex (28.2% women vs 23.4% men) and by age groups, with less than 2% of <16-year-old people and more than 50% of >80-year-old people being tested. Most of the symptoms commonly attributed to thyroid dysfunction were not higher in the thyroid dysfunction groups. Serum TSH levels were higher in older people particularly after the age of 60 years, in women (by 0.1 mIU/L), during the early hours of the morning, and in winter and spring seasons. There was remarkable uniformity in the frequency of subclinical thyroid dysfunction, as well as substantial cost savings, if TSH reference intervals were recalculated across sexes, age groups, time-periods and seasons.

CONCLUSIONS

Serum TSH is frequently tested in the population but is not a good discriminant of symptoms attributed to thyroid dysfunction. Furthermore, considering the influence of factors on TSH reference limits could significantly impact patient care and resource utilisation.

Triiodothyronine (T3), inflammation and mortality risk in patients with acute myocardial infarction

OBJECTIVES

To study the relationship between serum-free T3 (FT3), C-reactive protein (CRP) and all-cause mortality in patients with acute myocardial infarction (AMI).

DESIGN

Prospective multicentre longitudinal cohort study.

METHODS

Between December 2014 and December 2016, thyroid function and CRP were analysed in AMI (both ST-elevation (STEMI) and non-ST-elevation) patients from the Thyroxine in Acute Myocardial Infarction study. The relationship of FT3 and CRP at baseline with all-cause mortality up to June 2020 was assessed. Mediation analysis was performed to evaluate if CRP mediated the relationship between FT3 and mortality.

RESULTS

In 1919 AMI patients (29.2% women, mean (s.d.) age: 64.2 (12.1) years and 48.7% STEMI) followed over a median (interquartile range) period of 51 (46-58) months, there were 277 (14.4%) deaths. Overall, lower serum FT3 and higher CRP levels were associated with higher risk of mortality. When divided the patients into tertiles based on the levels of FT3 and CRP; the group with the lowest FT3 and highest CRP levels had a 2.5-fold increase in mortality risk (adjusted hazard ratio (95% CI) of 2.48 (1.82-3.16)) compared to the group with the highest FT3 and lowest CRP values. CRP mediated 9.8% (95% CI: 6.1-15.0%) of the relationship between FT3 and mortality.

CONCLUSIONS

In AMI patients, lower serum FT3 levels on admission are associated with a higher mortality risk, which is partly mediated by inflammation. Adequately designed trials to explore the potential benefits of T3 in AMI patients are required.

Association of diabetes with atrial fibrillation types: a systematic review and meta-analysis

Background

Atrial fibrillation (AF) is a common arrhythmia classified as paroxysmal and non-paroxysmal. Non-paroxysmal AF is associated with an increased risk of complications. Diabetes contributes to AF initiation, yet its role in AF maintenance is unclear. We conducted a systematic review and meta-analysis to summarize the evidence regarding the association of diabetes with AF types.

Methods

We searched 5 databases for observational studies investigating the association of diabetes with the likelihood of an AF type (vs another type) in humans. Study quality was evaluated using the Newcastle–Ottawa Scale. Studies classifying AF types as paroxysmal (reference) and non-paroxysmal were pooled in a meta-analysis using random effects models.

Results

Of 1997 articles we identified, 20 were included in our systematic review. The population sample size ranged from 64 to 9816 participants with mean age ranging from 40 to 75 years and percentage of women from 24.8 to 100%. The quality of studies varied from poor (60%) to fair (5%) to good (35%). In the systematic review, 8 studies among patients with AF investigated the cross-sectional association of diabetes with non-paroxysmal AF (vs paroxysmal) of which 6 showed a positive association and 2 showed no association. Fourteen studies investigated the longitudinal association of diabetes with “more sustained” AF types (vs “less sustained”) of which 2 showed a positive association and 12 showed no association. In the meta-analysis of cross-sectional studies, patients with AF and diabetes were 1.31-times more likely to have non-paroxysmal AF than those without diabetes [8 studies; pooled OR (95% CI), 1.31 (1.13–1.51), I² = 82.6%]. The meta-analysis of longitudinal studies showed that for patients with paroxysmal AF, diabetes is associated with 1.32-times increased likelihood of progression to non-paroxysmal AF [five studies; pooled OR (95% CI), 1.32 (1.07–1.62); I² = 0%].

Conclusions

Our findings suggest that diabetes is associated with an increased likelihood of non-paroxysmal AF rather than paroxysmal AF. However, further high quality studies are needed to replicate these findings, adjust for potential confounders, elucidate mechanisms linking diabetes to non-paroxysmal AF, and assess the impact of antidiabetic medications on AF types. These strategies could eventually help decrease the risk of non-paroxysmal AF among patients with diabetes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12933-021-01423-2.

A global country-level analysis of the relationship between obesity and COVID-19 cases and mortality

AIM

To assess the association of country-level obesity prevalence with COVID-19 case and mortality rates, to evaluate the impact of obesity prevalence on worldwide variation.

METHODS

Data on COVID-19 prevalence and mortality, country-specific governmental actions, socioeconomic, demographic, and healthcare capacity factors were extracted from publicly available sources. Multivariable negative binomial regression was used to assess the independent association of obesity with COVID-19 case and mortality rates.

RESULTS

Across 168 countries for which data were available, higher obesity prevalence was associated with increased COVID-19 mortality and prevalence rates. For every 1% increase in obesity prevalence, the mortality rate was increased by 8.3% (incidence rate ratio [IRR] 1.083, 95% confidence interval [CI] 1.048-1.119; P < 0.001) and the case rate was higher by 6.6% (IRR 1.066, 95% CI 1.035-1.099; P < 0.001). Additionally, higher median population age, greater female ratio, higher Human Development Index (HDI), lower population density, and lower hospital bed availability were all significantly associated with higher COVID-19 mortality rate. In addition, stricter governmental actions, higher HDI and lower mean annual temperature were significantly associated with higher COVID-19 case rate.

CONCLUSION

These findings demonstrate that obesity prevalence is a significant and potentially modifiable risk factor of increased COVID-19 national caseload and mortality. Future research to study whether weight loss improves COVID-19 outcomes is urgently required.

Does Clinical and Biochemical Thyroid Dysfunction Impact on Endometrial Cancer Survival Outcomes? A Prospective Database Study

Simple Summary

Endometrial cancer is the most common gynaecological cancer in high-income countries. Most women are diagnosed early and have an excellent prognosis, but those with advanced or recurrent disease have poor outcomes. The aim of this study was to determine whether clinical or biochemical thyroid dysfunction may contribute to survival outcomes following diagnosis and treatment for endometrial cancer. We analysed clinical data and serum thyroid hormone status of 333 women treated for endometrial cancer at a specialist cancer centre and followed up for a median of 35 months. Women with a diagnosis of hypothyroidism had improved overall, cancer-specific, and recurrence-free survival compared to those without. This may have important implications for our understanding of the mechanisms underpinning biologically aggressive disease and offer opportunities for therapeutic intervention.

Abstract

Endometrial cancer is the commonest gynaecological malignancy in developed countries, and women presenting with high risk or advanced disease have poor outcomes. Thyroid hormones play a key role in cellular metabolism and can influence cancer growth and invasion. Our aim was to evaluate the association between clinical and biochemical thyroid dysfunction and endometrial cancer survival outcomes. This was a prospective cohort study of women treated for endometrial cancer at a specialist centre. Clinical diagnosis of hypothyroidism was based on clinical and biochemical assessment, verified by general practitioner (GP) records. Pre-treatment serum samples were tested for thyrotropin (TSH), thyroid hormones (free T4 and total T3), and thyroid peroxidase antibodies. Kaplan–Meier survival estimates and log-rank tests were used to compare survival between groups, while Cox regression was used for multivariable analysis, adjusting for known confounders and effect modifications. In total, 333 women with median age and body mass index (BMI) of 66 years (interquartile range (IQR) 56, 73) and 33 kg/m² (IQR 27, 41) respectively were included. A total of 51 (15.3%) women had a diagnosis of hypothyroidism, 39 (11.9%) had biochemical evidence of overt or subclinical hypothyroidism. Median follow-up was 35 months (IQR 21, 45) with 38 (11.7%) relapses and 50 (15.0%) deaths. Women with a diagnosis of hypothyroidism had improved overall survival (adjusted HR = 0.22, 95%CI 0.06–0.74, p = 0.02), cancer-specific survival (adjusted HR = 0.21, 95%CI 0.05–0.98, p = 0.04) and fewer recurrences (adjusted HR = 0.17, 95%CI 0.04–0.77, p = 0.02) than those who did not. Confirmatory studies should explore underlying mechanisms and the potential for therapeutic exploitation.

Multinational Survey of Treatment Practices of Clinicians Managing Subclinical Hypothyroidism in Older People in 2019

BACKGROUND

International societies have recommended that levothyroxine should not routinely be prescribed in older individuals for the management of mild subclinical hypothyroidism (SCH). However, it is unknown whether clinicians managing people with SCH are either aware of or adhere to these guidelines.

METHODS

A web-based survey of members of several international thyroid associations and general practitioners in North-East England was conducted. Respondents were presented with a vignette of an 80-year-old gentleman with mild persistent SCH experiencing tiredness. Multivariable logistic regression analyses were performed to evaluate predictors of awareness of guidelines and responses to treatment.

RESULTS

The survey response rate was 21.9% (565/2,583). Only 7.6% of clinicians were unaware of guidelines regarding management of SCH in older people. Twenty percent of clinicians stated that they would treat the older patient with mild SCH, whereas 13% were unsure. Clinicians from North America were more likely to treat the older person with mild SCH than clinicians from elsewhere (OR 2.24 [1.25-3.98]). Likewise, non-endocrinologists were also more likely than endocrinologists to treat the older person with mild SCH (OR 3.26 [1.45-6.47]).

CONCLUSION

The majority of clinicians are aware of guidelines regarding management of SCH in older individuals. However, a considerable proportion of clinicians would still treat an older person with non-specific symptoms and mild SCH. These guidelines need to be disseminated more widely and more research is required to understand barriers to adherence to international recommendations.

Prevalence, predictors and outcomes of thyroid dysfunction in patients with acute myocardial infarction: the ThyrAMI-1 study

PURPOSE

Thyroid dysfunction in patients with cardiac disease is associated with worse outcomes. This study aimed to evaluate the prevalence and analyse predictors and outcomes of thyroid dysfunction in patients presenting with an acute myocardial infarction (AMI).

METHODS

A prospective multicentre observational study of patients recruited from six acute hospitals within the North of England. Consecutive patients without previous thyroid disease presenting with both ST-elevation AMI (STEMI) and non-ST-elevation AMI (NSTEMI) were recruited to the Thyroxine in Acute Myocardial Infarction 1 (ThyrAMI-1) cohort study between December 2014 and 2016. Thyroid profile, standard biochemistry measurements and demographic information were obtained within 12 h of admission to hospital. Multivariable logistic regression analyses were performed to assess the predictors of thyroid dysfunction and Cox proportional hazards analyses were utilised to compare all-cause mortality by categories of thyroid dysfunction up to June 2019.

RESULTS

Of the 1802 participants analysed, 1440 (79.9%) were euthyroid, 312 (17.3%) had subclinical hypothyroidism (SCH), 22 (1.2%) had subclinical hyperthyroidism (SHyper) and 25 (1.3%) had low T3 syndrome (LT3S). Predictors for SCH were increasing age, female sex, higher thyroid peroxidase antibody (TPOAb) levels, higher serum creatinine levels and early morning sampling time (between 00:01-06:00 h). The predictors of SHyper were lower body mass index and afternoon sampling time (between 12:01 and 18:00 h). Predictors of LT3S were increasing age, higher creatinine levels and presence of previous ischaemic heart disease. Compared to the euthyroid group, patients with LT3S had higher all-cause mortality; adjusted hazard ratio (95% CI) of 2.02 (1.03-3.95), p = 0.04, whereas those with SCH and SHyper did not exhibit significantly increased mortality; adjusted hazard ratios (95% CI) of 1.05 (0.74-1.49), p = 0.79 and 0.27 (0.04-1.95), p = 0.19, respectively.

CONCLUSIONS

Thyroid dysfunction is common in AMI patients on admission to hospital and our data provide an understanding regarding which factors might influence thyroid dysfunction in these patients. Furthermore, the negative association between LT3S and increased mortality post-AMI has once again been highlighted by this study. More research is required to assess if treatment of thyroid dysfunction improves clinical outcomes.

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.

Iatrogenic hypoglycaemia following glucose-insulin infusions for the treatment of hyperkalaemia

OBJECTIVES

To study the incidence of, and risk factors for, iatrogenic hypoglycaemia following GwI infusion in our institution.

CONTEXT

Hyperkalaemia is a life-threatening biochemical abnormality. Glucose-with-insulin (GwI) infusions form standard management, but risk iatrogenic hypoglycaemia (glucose ≤ 3.9 mmol/L). Recently updated UK guidelines include an additional glucose infusion in patients with pretreatment capillary blood glucose (CBG) < 7.0 mmol/L.

DESIGN

Retrospective analysis of outcomes for GwI infusions prescribed for hyperkalaemia from 1 January to 28 February 2019, extracted from the Newcastle upon Tyne Hospitals NHS Foundation Trust electronic platform (eRecord).

PARTICIPANTS

132 patients received 228 GwI infusions for hyperkalaemia.

MAIN OUTCOME MEASURES

Incidence, severity and time to onset of hypoglycaemia.

RESULTS

Hypoglycaemia incidence was 11.8%. At least 1 hypoglycaemic episode occurred in 18.2% of patients with 6.8% having at least 1 episode of severe hypoglycaemia (< 3.0 mmol/L). Most episodes (77.8%) occurred within 3 h of treatment. Lower pretreatment CBG (5.9 mmol/L [4.1 mmol/L-11.2 mmol/L], versus 7.6 mmol/L [3.7 mmol/L-31.3 mmol/L], P = .000) was associated with hypoglycaemia risk. A diagnosis of type 2 diabetes and treatment for hyperkalaemia within the previous 24 h were negatively associated.

CONCLUSIONS

Within our inpatient population, around 1 in 8 GwI infusions delivered as treatment for hyperkalaemia resulted in iatrogenic hypoglycaemia. Higher pretreatment CBG and a diagnosis of type 2 diabetes were protective, irrespective of renal function. Our findings support the immediate change to current management, either with additional glucose infusions or by using glucose-only infusions in patients without diabetes. These approaches should be compared via a prospective randomized study.

Obesity: A critical risk factor in the COVID-19 pandemic

Obesity is an emerging independent risk factor for susceptibility to and severity of coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Previous viral pandemics have shown that obesity, particularly severe obesity (BMI > 40 kg/m2 ), is associated with increased risk of hospitalization, critical care admission and fatalities. In this narrative review, we examine emerging evidence of the influence of obesity on COVID-19, the challenges to clinical management from pulmonary, endocrine and immune dysfunctions in individuals with obesity and identify potential areas for further research. We recommend that people with severe obesity be deemed a vulnerable group for COVID-19; clinical trials of pharmacotherapeutics, immunotherapies and vaccination should prioritize inclusion of people with obesity.

Managing symptoms in hypothyroid patients on adequate levothyroxine: a narrative review

The current standard of care for hypothyroidism is levothyroxine (LT4) monotherapy to reduce levels of thyrotropin (thyroid-stimulating hormone, TSH) within its reference range and amelioration of any symptoms. A substantial minority continues to report hypothyroid-like symptoms despite optimized TSH, however. These symptoms are not specific to thyroid dysfunction and are frequent among the euthyroid population, creating a therapeutic dilemma for the treating clinician as well as the patient. We present a concise, narrative review of the clinical research and evidence-based guidance on the management of this challenging population. The clinician may endeavor to ensure that the serum TSH is within the target range. However, the symptomatic patient may turn to alternative non-evidence-based therapies in the hope of obtaining relief. Accordingly, it is important for the clinician to check for conditions unrelated to the thyroid that could account for the ongoing symptoms such as other autoimmune conditions, anemia or mental health disorders. Systematic and thorough investigation of the potential causes of persistent symptoms while receiving LT4 therapy will resolve the problem for most patients. There may be some patients that may benefit from additional treatment with liothyronine (LT3), although it is unclear as yet as to which patient group may benefit the most from combined LT4 + LT3 therapy. In the future, personalized treatment with LT4 + LT3 may be of benefit for some patients with persistent symptoms of hypothyroidism such as those with polymorphisms in the deiodinase enzyme 2 (DIO2). For now, this remains a subject for research.

Exposure of hospital healthcare workers to the novel coronavirus (SARS-CoV-2)

Healthcare workers (HCWs) are at higher risk of infection with the coronavirus disease 2019 (COVID-19) and can also amplify outbreaks within healthcare facilities if they become ill. Certain groups are known to be at higher risk of contracting severe COVID-19 infection, such as men and people from Black, Asian and minority ethnic (BAME) backgrounds. Identifying and managing HCWs who have been exposed to COVID-19 is of utmost importance in preventing healthcare transmission and protecting staff and vulnerable patients in healthcare settings. Recently, antibody testing to diagnose previous COVID-19 exposure among HCW has commenced in the UK. This provided an opportunity to assess exposure to COVID-19 among the various subgroups within the HCW community, based on their roles and ethnic background. We found that HCWs working in patient-facing roles were twice as likely to have been exposed to COVID-19 than their colleagues in non-patient-facing roles. Reassuringly, workers from BAME backgrounds had a similar risk of previous COVID-19 exposure to their white colleagues. More research is required to assess how frontline staff, especially those working in patient facing roles, can reduce their risk of exposure to COVID-19.

Effect of Levothyroxine on Left Ventricular Ejection Fraction in Patients With Subclinical Hypothyroidism and Acute Myocardial Infarction: A Randomized Clinical Trial

IMPORTANCE

Thyroid hormones play a key role in modulating myocardial contractility. Subclinical hypothyroidism in patients with acute myocardial infarction is associated with poor prognosis.

OBJECTIVE

To evaluate the effect of levothyroxine treatment on left ventricular function in patients with acute myocardial infarction and subclinical hypothyroidism.

DESIGN, SETTING, AND PARTICIPANTS

A double-blind, randomized clinical trial conducted in 6 hospitals in the United Kingdom. Patients with acute myocardial infarction including ST-segment elevation and non-ST-segment elevation were recruited between February 2015 and December 2016, with the last participant being followed up in December 2017.

INTERVENTIONS

Levothyroxine treatment (n = 46) commencing at 25 µg titrated to aim for serum thyrotropin levels between 0.4 and 2.5 mU/L or identical placebo (n = 49), both provided in capsule form, once daily for 52 weeks.

MAIN OUTCOMES AND MEASURES

The primary outcome measure was left ventricular ejection fraction at 52 weeks, assessed by magnetic resonance imaging, adjusted for age, sex, type of acute myocardial infarction, affected coronary artery territory, and baseline left ventricular ejection fraction. Secondary measures were left ventricular volumes, infarct size (assessed in a subgroup [n = 60]), adverse events, and patient-reported outcome measures of health status, health-related quality of life, and depression.

RESULTS

Among the 95 participants randomized, the mean (SD) age was 63.5 (9.5) years, 72 (76.6%) were men, and 65 (69.1%) had ST-segment elevation myocardial infarction. The median serum thyrotropin level was 5.7 mU/L (interquartile range, 4.8-7.3 mU/L) and the mean (SD) free thyroxine level was 1.14 (0.16) ng/dL. The primary outcome measurements at 52 weeks were available in 85 patients (89.5%). The mean left ventricular ejection fraction at baseline and at 52 weeks was 51.3% and 53.8%, respectively, in the levothyroxine group compared with 54.0% and 56.1%, respectively, in the placebo group (adjusted difference in groups, 0.76% [95% CI, -0.93% to 2.46%]; P = .37). None of the 6 secondary outcomes showed a significant difference between the levothyroxine and placebo treatment groups. There were 15 (33.3%) and 18 (36.7%) cardiovascular adverse events in the levothyroxine and placebo groups, respectively.

CONCLUSIONS AND RELEVANCE

In this preliminary study involving patients with subclinical hypothyroidism and acute myocardial infarction, treatment with levothyroxine, compared with placebo, did not significantly improve left ventricular ejection fraction after 52 weeks. These findings do not support treatment of subclinical hypothyroidism in patients with acute myocardial infarction.

TRIAL REGISTRATION

isrctn.org Identifier: http://www.isrctn.com/ISRCTN52505169.

Thyroid Function and the Risk of Fibrosis of the Liver, Heart, and Lung in Humans: A Systematic Review and Meta-Analysis

Background: Fibrotic diseases have an unclear etiology and poor prognosis. Fluctuations in thyroid function may play a role in the development of fibrosis, but evidence is fragmented and inconclusive. This systematic review and meta-analysis aimed to investigate the association of thyroid function with fibrotic diseases of the liver, heart, and lung in humans. Methods: We searched PubMed, Medline Ovid, Embase Ovid, and Web-of-Science for studies published from inception to 14 June 2019, to identify observational studies that investigated the association of thyroid function with fibrosis of the liver, heart, and lung in humans. Study quality was evaluated by the Newcastle-Ottawa Scale. The Mantel-Haenszel method was used to pool the odds ratios (ORs) of studies investigating the association of hypothyroidism with liver fibrosis. Results: Of the 2196 identified articles, 18 studies were included in the systematic review, of which 11 studies reported on liver fibrosis, 4 on myocardial fibrosis, and 3 on pulmonary fibrosis. The population sample size ranged from 36 to 7259 subjects, with median mean age 51 years (range, 36-69) and median percentage of women 53 (range, 17-100). The risk of bias of studies was low to moderate to high. Higher serum thyrotropin and lower thyroid hormone levels were generally associated with higher likelihood of fibrosis. Compared with euthyroidism, overt and subclinical hypothyroidism was associated with a higher likelihood of fibrosis in the liver (six of seven studies), heart (three of three studies), and lung (three of three studies). Based on the results of the seven studies included in the meta-analysis, overt and subclinical hypothyroidism was associated with an increased risk of liver fibrosis (pooled OR, 2.81; 95% confidence interval [CI], 1.74-4.53; heterogeneity, I² 31.4%; pooled OR, 2.12; CI, 1.45-3.12; heterogeneity, I² 0%; respectively), without evidence of publication bias. Conclusions: This study suggests that low thyroid function is associated with increased likelihood of chronic fibrotic diseases of the liver, heart, and lung. However, the evidence is mainly based on cross-sectional data. Prospective studies and randomized clinical trials are needed to investigate the potential efficacy of thyroid hormone and its analogs on the occurrence and progression of fibrosis.

Sample Timing, Diagnosis of Subclinical Thyroid Dysfunction and Mortality in Acute Myocardial Infarction: ThyrAMI1 Study

OBJECTIVE

The objective of this study was to determine the impact of blood sample timing on the diagnosis of subclinical thyroid dysfunction (SCTD) and mortality in patients with acute myocardial infarction (AMI).

PATIENTS, DESIGN, AND MAIN OUTCOME MEASURES

Patients with AMI had thyroid function evaluated on admission between December 2014 and December 2016 and those with abnormal serum thyrotropin (TSH) had repeat thyroid function assessed at least a week later. The association between sample timing and SCTD was evaluated by logistic regression analysis. Secondary outcomes were confirmation of SCTD on repeat testing and all-cause mortality up to June 2018.

RESULTS

Of the 1806 patients [29.2% women, mean (± standard deviation) age of 64.2 (±12.1) years] analyzed, the prevalence of subclinical hypothyroidism (SCH) was 17.2% (n = 311) and subclinical hyperthyroidism (SHyper) was 1.2% (n = 22) using a uniform TSH reference interval. The risk of being diagnosed with SCTD varied by sample timing in fully-adjusted models. The risk of SCH was highest between 00.01 and 06.00 hours and lowest between 12.01 and 18.00 hours, P for trend <.001, and risk of SHyper was highest between 12.01 hours and 18.00 hours and lowest between 00.01 hours and 06.00 hours. Furthermore, time of the initial sample was associated with the risk of remaining in a SCH state subsequently. Mortality in SCH patients was not elevated when a uniform TSH reference interval was utilized. However, when time period-specific TSH reference ranges were utilized, the mortality risk was significantly higher in SCH patients with HR (95% CI) of 2.26 (1.01-5.19), P = .04.

CONCLUSIONS

Sample timing impacts on the diagnosis and prognosis of SCH in AMI patients. If sample timing is not accounted for, SCH is systemically misclassified, and its measurable influence on mortality is lost.

Age-Related Serum Thyroid-Stimulating Hormone Reference Range in Older Patients Treated with Levothyroxine: A Randomized Controlled Feasibility Trial (SORTED 1)

INTRODUCTION

Serum thyroid-stimulating hormone (TSH) increases with age but target TSH is similar in younger and older hypothyroid patients on treatment. It is unknown if quality of life (QoL), hypothyroid symptoms and cardiovascular risk factors change in older hypothyroid patients treated to an age-appropriate reference range.

OBJECTIVE

To assess if a higher target serum TSH of 4.01-8.0 mU/L is feasible in, and acceptable to, older treated hypothyroid patients.

METHODS

A single-blind (participant) randomised controlled feasibility trial involving 48 hypothyroid patients aged ≥80 years on established and stable levothyroxine (LT4) therapy with serum TSH levels within the standard reference range (0.4-4.0 mU/L) was conducted. Standard (0.4-4.0 mU/L) or higher (4.1-8.0 mU/L) TSH target (standard TSH [ST] or higher TSH [HT] groups) LT4 for 24 weeks was administered. The outcome measures evaluated were thyroid function tests, QoL, hypothyroid symptoms, cardiovascular risk factors and serum marker of bone resorption in participants that completed the trial (n = 21/24 ST group, n = 19/24 HT group).

RESULTS

At 24 weeks, in the ST and HT groups, respectively, median (interquartile range) serum TSH was 1.25 (0.76-1.72) and 5.50 (4.05-9.12) mU/L, mean (± SD) free thyroxine (FT4) was 19.4 ± 3.5 and 15.9 ± 2.4 pmol/L, and daily LT4 dose was 82.1 ± 26.4 and 59.2 ± 23.9 µg. There was no suggestion of adverse impact of a higher serum TSH in the HT group with regard to any of the outcomes assessed.

CONCLUSIONS

In hypothyroid patients aged ≥80 years on LT4 therapy for 24 weeks, there was no evidence that a higher target serum TSH was associated with an adverse impact on patient reported outcomes, cardiovascular risk factors or bone resorption marker over 24 weeks. Longer-term trials assessing morbidity and mortality outcomes and health-utility in this age group are feasible and should be performed.

Novel uses of thyroid hormones in cardiovascular conditions

Thyroid hormone levels are reduced in cardiovascular diseases and this phenomenon is associated with worse outcomes. It is unclear whether the changes in thyroid hormone bioavailability to the affected myocardium are beneficial or if this is a maladaptive response. Experimental studies from animal models of acute myocardial infarction (AMI) suggest that thyroid hormone treatment may be beneficial. There is limited data available on the use of thyroid hormones in patients with AMI and heart failure and this suggests that treatment to normalise thyroid hormone levels may be safe and potentially efficacious. Similarly, evidence of thyroid hormone therapy in patients undergoing cardiac surgery or during cardiac transplantation is limited. It is therefore difficult to draw any firm conclusions about benefits or risks of thyroid hormone treatment in these conditions. Large scale clinical trials of thyroid hormones in patients with cardiac conditions are required to confirm safety and evaluate efficacy. Furthermore, it needs to be elucidated which hormone to administer (thyroxine or triiodothyronine), when in the disease pathway to treat, dose of thyroid hormone to administer, and which parameters to utilise to assess safety and efficacy. Until these important questions are answered thyroid hormone therapy in cardiovascular diseases must remain within the research domain.

Thyroid Hormones and Cardiovascular Function and Diseases

Thyroid hormone (TH) receptors are present in the myocardium and vascular tissue, and minor alterations in TH concentration can affect cardiovascular (CV) physiology. The potential mechanisms that link CV disease with thyroid dysfunction are endothelial dysfunction, changes in blood pressure, myocardial systolic and diastolic dysfunction, and dyslipidemia. In addition, cardiac disease itself may lead to alterations in TH concentrations (notably, low triiodothyronine syndrome) that are associated with higher morbidity and mortality. Experimental data and small clinical trials have suggested a beneficial role of TH in ameliorating CV disease. The aim of this review is to provide clinicians dealing with CV conditions with an overview of the current knowledge of TH perturbations in CV disease.

Antigen-Specific Immunotherapy with Thyrotropin Receptor Peptides in Graves' Hyperthyroidism: A Phase I Study

Background: Graves' disease is one of the most common autoimmune conditions, but treatment remains imperfect. This study explores the first-in-human use of antigen-specific immunotherapy with a combination of two thyrotropin receptor (TSHR) peptides (termed ATX-GD-59) in Graves' hyperthyroidism. Methods: Twelve participants (11 female) with previously untreated mild to moderate Graves' hyperthyroidism were enrolled in a Phase I open label trial to receive 10 doses of ATX-GD-59 administered intradermally over an 18-week period. Adverse events, tolerability, changes in serum free thyroid hormones, and TSHR autoantibodies were measured. Results: Ten subjects received all 10 doses of ATX-GD-59, five (50%) of whom had free triiodothyronine within the reference interval by the 18-week visit. Two further subjects had improved free thyroid hormones by the end of the study (7/10 responders), whereas three subjects showed worsening thyrotoxicosis during the study. Serum TSHR autoantibody concentrations reduced during the study and correlated with changes in free thyroid hormones (r = 0.85, p = 0.002 for TSHR autoantibody vs. free triiodothyronine). Mild injection-site swelling and pain were the most common adverse events. Conclusions: These preliminary data suggest that ATX-GD-59 is a safe and well-tolerated treatment. The improvement in free thyroid hormones in 70% of subjects receiving the medication suggests potential efficacy as a novel treatment for Graves' hyperthyroidism.

Therapeutic challenges in the application of serum thyroid stimulating hormone testing in the management of patients with hypothyroidism on replacement thyroid hormone therapy: a review

Normalizing serum thyroid stimulating hormone (TSH) levels by lifelong treatment with levothyroxine (LT4) remains the primary goal of therapy for patients with hypothyroidism. The reference ranges for TSH are derived from populations with (supposedly) normal thyroid function. But, TSH results are affected by a number of factors including alterations in TSH levels with age, concurrent illnesses, circadian rhythm, inter- and intra-assay differences, and some commonly used medications that interfere with thyroid function or the TSH test. Furthermore, some patients are complex to manage and bringing serum TSH to within its reference range does not always resolve their symptoms of hypothyroidism. Furthermore, changes in TSH within the reference range may provoke symptoms in some sensitive patients, and others may have a personal "set point" for thyroid hormone levels that represents normal function for that individual, but which is outside the population reference range. The introduction of updated LT4 formulations, with better dosing accuracy and stability compared with older versions, should, in theory at least, provide better stability and accuracy of dosing over time. However, the new LT4 formulations are associated with manifold increases in the number of self-reported adverse events. Therefore, patients with hypothyroidism as well as the clinicians managing them need to better understand the utility as well as the limitations of the widely used TSH measurement. In addition, both pharmaceutical companies and the prescribing clinician need to take greater care when patients are switched from older to newer formulations.

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.

Age May Influence the Impact of TRAbs on Thyroid Function and Relapse-Risk in Patients With Graves Disease

CONTEXT

Thyrotropin receptor antibodies (TRAbs) play a crucial role in the pathogenesis of Graves disease (GD). However, factors that influence the association of TRAbs with thyroid hormones and relapse risk in GD remain unclear.

OBJECTIVE

We investigated the associations of TRAbs at diagnosis with thyroid hormones and relapse risk and potential factors that can influence these associations in GD.

DESIGN AND SETTING

A prospective study in an endocrine center in England.

PATIENTS AND MAIN OUTCOME MEASURES

Three hundred eighty-four consecutive patients with GD who had measurements of TRAbs and thyroid hormones at diagnosis. The association of TRAbs with thyroid hormones and relapse risk was assessed through linear regression and Cox proportional hazard models, adjusted for confounders.

RESULTS

TRAbs were nonlinearly associated with thyroid hormones, following a curve with an initial positive slope and a subsequent flattening (P < 0.0001). Higher TRAbs were associated with greater relapse risk [hazard ratio (HR), 1.05 (95% CI, 1.02 to 1.08) per 1-U/L increase]. These associations were modified by age, but not by sex, race, smoking, or thyroid peroxidase antibody levels. In younger participants, increasing TRAbs were associated with higher thyroid hormones and greater relapse risk [HR, 1.13 (95% CI, 1.04 to 1.23) per 1-U/L increase]. In older participants, TRAbs were not associated with thyroid hormones or relapse risk [HR, 0.99 (95% CI, 0.93 to 1.05) per 1-U/L increase.

CONCLUSIONS

In GD, age can influence the effect of TRAbs on thyroid function and relapse risk. TRAbs at diagnosis have better predictive value in younger patients with GD.

Hypothyroidism in the older population

BACKGROUND

Both overt hypothyroidism as well as minor elevations of serum thyrotropin (TSH) levels associated with thyroid hormones within their respective reference ranges (termed subclinical hypothyroidism) are relatively common in older individuals. There is growing evidence that treatment of subclinical hypothyroidism may not be beneficial, particularly in an older person. These findings are relevant at a time when treatment with thyroid hormones is increasing and more than 10-15% of people aged over 80 years are prescribed levothyroxine replacement therapy.

MAIN BODY

The prevalence of hypothyroidism increases with age. However, the reference range for TSH also rises with age, as the population distribution of TSH concentration progressively rises with age. Furthermore, there is evidence to suggest that minor TSH elevations are not associated with important outcomes such as impaired quality of life, symptoms, cognition, cardiovascular events and mortality in older individuals. There is also evidence that treatment of mild subclinical hypothyroidism may not benefit quality of life and/or symptoms in older people. It is unknown whether treatment targets should be reset depending on the age of the patient. It is likely that some older patients with non-specific symptoms and incidental mild subclinical hypothyroidism may be treated with thyroid hormones and could potentially be harmed as a result. This article reviews the current literature pertaining to hypothyroidism with a special emphasis on the older individual and assesses the risk/benefit impact of contemporary management on outcomes in this age group.

CONCLUSIONS

Current evidence suggests that threshold for treating mild subclinical hypothyroidism in older people should be high. It is reasonable to aim for a higher TSH target in treated older hypothyroid patients as their thyroid hormone requirements may be lower. In addition, age-appropriate TSH reference ranges should be considered in the diagnostic pathway of identifying individuals at risk of developing hypothyroidism. Appropriately designed and powered randomised controlled trials are required to confirm risk/benefit of treatment of subclinical hypothyroidism in older people. Until the results of such RCTs are available to guide clinical management international guidelines should be followed that advocate a conservative policy in the management of mild subclinical hypothyroidism in older individuals.

Trends, Determinants, and Associations of Treated Hypothyroidism in the United Kingdom, 2005-2014

BACKGROUND

Recent reports suggest that prescriptions for thyroid hormones have increased. Recent trends in and determinants of the prevalence of treated hypothyroidism across the United Kingdom were therefore analyzed.

METHODS

Data covering the whole of the United Kingdom held by the National Health Service and the Office of National Statistics were examined. The main outcome measured was trends in the prevalence of treated hypothyroidism between 2005 and 2014. In addition, linear trend forecasting was performed to estimate projected trends in the prevalence of treated hypothyroidism up to the year 2025. Furthermore, determinants of variation of treated hypothyroidism prevalence across each of the 237 health areas in the United Kingdom in 2014 and its association with other health conditions were explored by multivariate linear regression analyses.

RESULTS

The prevalence of treated hypothyroidism increased from 2.3% (1.4 million) to 3.5% (2.2 million) of the total British population between the years 2005 and 2014 and is projected to rise further to 4.2% (2.9 million) by 2025. There was large geographical variation of treated hypothyroidism across the United Kingdom, with London having the lowest (1.4%) and the Western Isles of Scotland having the highest (6.3%) prevalence. This variation was attenuated, but did not completely disappear, after some potential determinants were accounted for. The prevalence of treated hypothyroidism was independently related to health areas, with a higher proportion of individuals who were female, white, and obese, and negatively associated with prevalent cigarette smoking. The prevalence of treated hypothyroidism was significantly associated with the frequency of prevalent atrial fibrillation but not with other major health conditions, including ischemic heart disease and osteoporosis.

CONCLUSIONS

Between 2005 and 2014, the prevalence of treated hypothyroidism increased across the United Kingdom, has wide geographical variation, and is likely to increase further for the foreseeable future. Clinical effects and cost-effectiveness of the trend in increasing treatment of hypothyroidism remains to be evaluated.

Analysis of BAFF gene polymorphisms in UK Graves' disease patients

OBJECTIVE

B lymphocyte activating factor (BAFF), a member of the tumour necrosis factor superfamily, is essential for B cell activation, differentiation and survival. Elevated circulating BAFF levels have been found in patients with several autoimmune conditions, including Graves' disease. In addition, BAFF gene variants have been associated with Graves' disease in a Taiwanese cohort, and with several other autoimmune conditions in non-Taiwanese populations.

DESIGN AND METHODS

We performed a case-control association study to investigate two BAFF polymorphisms (rs9514828 and rs4000607) in a UK cohort of 444 patients with Graves' disease. Genotype frequencies were compared to those from 447 local controls and more than 5000 healthy controls from the Wellcome Trust case-control consortium (WTCCC2).

RESULTS

There was a significant difference in the frequency of the AA genotype at rs4000607 between the Graves' disease cohort and both the local controls (P = 0.045) and the WTCCC2 controls (P = 4.56 × 10^-6 ). Furthermore, the frequency of the A allele was found to be increased in the Graves' disease group compared to WTCCC2 controls (P = 0.02, OR 1.20 (95% CI 1.03-1.41). No association was observed at the rs9514828 locus.

CONCLUSION

Dysfunction of the humoral immune system is an obligatory pathophysiological component of Graves' disease, hence BAFF is an excellent functional candidate gene. We have demonstrated, for the first time, a significant association of the BAFF polymorphism rs4000607 with Graves' disease in a UK cohort. Further work to elucidate the role of BAFF in the pathogenesis of Graves' disease is now warranted.

The Relation Between Thyroid Function and Anemia: A Pooled Analysis of Individual Participant Data

Context

Anemia and thyroid dysfunction often co-occur, and both increase with age. Human data on relationships between thyroid disease and anemia are scarce.

Objective

To investigate the cross-sectional and longitudinal associations between clinical thyroid status and anemia.

Design

Individual participant data meta-analysis.

Setting

Sixteen cohorts participating in the Thyroid Studies Collaboration (n = 42,162).

Main Outcome Measures

Primary outcome measure was anemia (hemoglobin <130 g/L in men and <120 g/L in women).

Results

Cross-sectionally, participants with abnormal thyroid status had an increased risk of having anemia compared with euthyroid participants [overt hypothyroidism, pooled OR 1.84 (95% CI 1.35 to 2.50), subclinical hypothyroidism 1.21 (1.02 to 1.43), subclinical hyperthyroidism 1.27 (1.03 to 1.57), and overt hyperthyroidism 1.69 (1.00 to 2.87)]. Hemoglobin levels were lower in all groups compared with participants with euthyroidism. In the longitudinal analyses (n = 25,466 from 14 cohorts), the pooled hazard ratio for the risk of development of anemia was 1.38 (95% CI 0.86 to 2.20) for overt hypothyroidism, 1.18 (1.00 to 1.38) for subclinical hypothyroidism, 1.15 (0.94 to 1.42) for subclinical hyperthyroidism, and 1.47 (0.91 to 2.38) for overt hyperthyroidism. Sensitivity analyses excluding thyroid medication or high levels of C-reactive protein yielded similar results. No differences in mean annual change in hemoglobin levels were observed between the thyroid hormone status groups.

Conclusion

Higher odds of having anemia were observed in participants with both hypothyroid function and hyperthyroid function. In addition, reduced thyroid function at baseline showed a trend of increased risk of developing anemia during follow-up. It remains to be assessed in a randomized controlled trial whether treatment is effective in reducing anemia.

Older patients' experience of primary hypothyroidism: A qualitative study

BACKGROUND

Primary hypothyroidism is a common endocrine disorder, more so in an increasing UK ageing population. There is no qualitative research examining the older patient perspective of symptoms, treatment and self-management of hypothyroidism.

OBJECTIVE

In this study we explored the experience of hypothyroidism in older people and examined how this may influence their understanding and acceptance of diagnosis, treatment with Levothyroxine and the monitoring process.

DESIGN

We conducted semi-structured interviews with 18 participants aged between 80 and 93 years. Interview transcripts were analysed using a thematic approach.

RESULTS

The themes involved older individuals' knowledge about symptoms, confidence in diagnosis and understanding of clinical management regimen to understand hypothyroidism. Interpretation of the themes was informed by the Health Belief Model.

CONCLUSION

Our findings can help to inform the development of interventions by treating clinicians and support staff to engage older patients in the long-term management of this chronic condition.

Attitudes and perceptions of health professionals towards management of hypothyroidism in general practice: a qualitative interview study

OBJECTIVE

To explore the attitudes and perceptions of health professionals towards management of hypothyroidism that contributes to the suboptimal treatment of hypothyroidism in general practice.

DESIGN

A qualitative interview study using semistructured interviews.

PARTICIPANTS

Sixteen participants were interviewed between March and August 2016 comprising nine general practitioners (GPs), four pharmacists, two practice nurses and one nurse practitioner.

SETTING

General practice and community pharmacies in the counties of Northumberland, Tyne and Wear, Stockton-on-Tees and North Cumbria, North of England, UK.

METHOD

A grounded-theory approach was used to generate themes from interviews, which were underpinned by the theory of planned behaviour to give explanation to the data.

RESULTS

Although health professionals felt that hypothyroidism was easy to manage, GPs and nurses generally revealed inadequate knowledge of medication interactions and levothyroxine pharmacokinetics. Pharmacists felt limited in the advice that they provide to patients due to lack of access to patient records. Most GPs and nurses followed local guidelines, and relied on blood tests over clinical symptoms to adjust levothyroxine dose. The information exchanged between professional and patient was usually restricted by time and often centred on symptoms rather than patient education. Health professionals felt that incorrect levothyroxine adherence was the main reason behind suboptimal treatment, although other factors such as comorbidity and concomitant medication were mentioned. Enablers perceived by health professionals to improve the management of hypothyroidism included continuity of care, blood test reminders, system alerts for interfering medications and prescription renewal, and accessible blood tests and levothyroxine prescriptions for patients.

CONCLUSION

There is a significant health professional behavioural component to the management of hypothyroidism. Addressing the differences in patient and professional knowledge and perceptions could reduce the barriers to optimal treatment, while continuity of care and increased involvement of pharmacists and practice nurses would help to promote optimal thyroid replacement.