Subclinical thyroid dysfunction and autoantibodies in acute ischemic and hemorrhagic stroke patients: relation to long term stroke outcome

Background Data regarding the relation between both subclinical thyroid dysfunction, thyroid autoantibodies and clinical outcomes in stroke patients are limited. This study aimed to evaluate subclinical thyroid dysfunction and thyroid autoantibodies production in acute stroke patients and their relation to long term stroke outcome. We recruited 138 patients who were subjected to thorough general, neurological examination and brain imaging. Blood samples were collected for measurement of levels of serum thyroid function [free tri-iodothyronine (FT3), free thyroxin (FT4), thyroid stimulating hormone (TSH)], thyroid autoantibodies within 48 h after hospital admission. FT4 and TSH after 1 year were done. The stroke severity was assessed at admission by the National Institutes of Health Stroke Scale (NIHSS). The stroke outcome was assessed at 3 months and after 1 year by the modified Rankin Scale (mRS). We divided the patients into two groups according to thyroid autoantibodies (positive and negative groups). Results Subclinical hyperthyroidism was found in 23% of patients, and subclinical hypothyroidism in 10% of patients. Euthyroidism was detected in 67% of patients. 34% patients had positive thyroid autoantibody. Positive thyroid autoantibodies were commonly found in those with subclinical hyperthyroidism (28%), followed by subclinical hypothyroidism (21%) and euthyroidism (14%). 73% and 59% of stroke patients had poor outcomes (mRS was > 2) at 3 months and 1 year respectively with no significant difference between ischemic and hemorrhagic stroke patients. In the positive group final TSH level, NIHSS score at admission, and disability at 1 year were significantly higher compared with the negative group. Poor outcome was significantly associated with higher NIHSS score at admission, positive thyroid autoantibodies, subclinical hyperthyroidism, and atrial fibrillation. Conclusions Subclinical thyroid dysfunction could be found in stroke patients with positive thyroid autoantibodies. Subclinical hyperthyroidism and thyroid autoantibodies were associated with a poor outcome at 1 year in first-ever acute stroke patients especially in those presented with atrial fibrillation and higher NIHSS score at admission.

Challenges in the Management of Atrial Fibrillation With Subclinical Hyperthyroidism

Subclinical thyroid disorders have a high prevalence among older individuals and women. Subclinical hypothyroidism is diagnosed by elevated serum levels of thyroid-stimulating hormone (TSH) with thyroxine levels within the reference range, and subclinical hyperthyroidism is diagnosed by low TSH in conjunction with thyroxine and triiodothyronine levels within reference ranges. Atrial fibrillation is the most commonly diagnosed cardiac arrhythmia and has been associated with an increased risk of mortality, heart failure, stroke, and depression. Mechanistic data from animal and human physiology studies as well as observational data in humans support an association of subclinical hyperthyroidism with atrial fibrillation. Guidelines recommend the measurement of TSH in the evaluation of new-onset atrial fibrillation. All patients with overt hyperthyroidism should be treated, and treatment of subclinical hyperthyroidism should be considered in patients older than 65 years with TSH < 0.4 mlU/L, or in younger patients with TSH < 0.1 mlU/L. Guidelines also recommend screening for AF in patients with known hyperthyroidism. Wearable devices that measure the heart electrical activity continuously may be a novel strategy to detect atrial fibrillation in patients at risk. In this review, we explore the interplay between thyroid hormones and atrial fibrillation, management controversies in subclinical hyperthyroidism, and potential strategies to improve the management of atrial fibrillation in patients with subclinical hyperthyroidism.

The Association with Subclinical Thyroid Dysfunction and Uric Acid

The relationship between subclinical thyroid dysfunction and uric acid was not well established. This study aimed to determine if subclinical thyroid dysfunction is associated with hyperuricemia risk and to evaluate the levels of uric acid in patients with different forms of subclinical thyroid dysfunction. A systematic search was conducted in 4 databases to obtain relevant studies on subclinical thyroid dysfunction (subclinical hyperthyroidism and subclinical hypothyroidism) and uric acid. The standardized mean difference (SMD) or odds ratio (OR) and 95% confidence interval (95% CI) were used for evaluation, and the sensitivity analysis was conducted. Publication bias was estimated by funnel plot, Egger’s test, and Begg’s test. A total of 73 studies were included in this meta-analysis. The results demonstrated that serum levels of uric acid in patients with subclinical hypothyroidism were significantly higher than those of controls and patients with subclinical hyperthyroidism. Patients with subclinical thyroid dysfunction had a higher prevalence of hyperuricemia compared with normal clinical thyroid function. Subclinical thyroid dysfunction was associated with the prevalence of hyperuricemia. Different types of subclinical thyroid dysfunction had varied effects on serum levels of uric acid.

Isfahan Thyroid Cohort Study (ITCS)

Background: The Isfahan Thyroid Cohort Study (ITCS) is one of the few population-based epidemiological studies in Iran that investigates the prevalence and incidence of thyroid disorders including hypothyroidism, hyperthyroidism, goiter, nodule, and iodine status. Methods: This cohort is located in Isfahan, Iran. The first phase was initiated in 2006 with 2523 participants (1275 males, 1248 females). The participants were selected using multi-stage cluster sampling from the general residents of Isfahan, Iran. The study had two phases (2006 and 2011) and its third stage is planned for 2020–2021. Results: The prevalence of thyroid function states was euthyroid (89.3%, 95% CI: 88%–90%), overt hypothyroidism (2.8%, 95% CI: 2%‒3%), subclinical hypothyroidism (5.8%, 95% CI: 4%–6%), overt hyperthyroidism (0.8%, 95% CI: 0.4%‒1%), and subclinical hyperthyroidism (0.99%, 95% CI: 0.6%–1%). Hypothyroidism and hyperthyroidism were significantly associated with goiter. The incidence of thyroid dysfunction was reported as follows: overt hypothyroidism (2.7, 95% CI: 1.6–3.7), subclinical hypothyroidism (20.6, 95% CI: 18–23), overt hyperthyroidism (1.9, 95% CI: 1–2.7) and subclinical hyperthyroidism (2.7, 95% CI: 1.6–3.7) per 1000 (person-year). Conclusion: We assessed the prevalence and incidence of thyroid disorders in Isfahan in the first and second phase, respectively. We are conducting the third phase of the ITCS in order to study the associations between thyroid peroxidase antibody (TPOAb) level and environmental factors such as infection.

Effect of the transition from more than adequate iodine to adequate iodine on national changes in the prevalence of thyroid disorders: Repeat national cross-sectional surveys in China

Objective: Longitudinal studies have investigated the effects of changing iodine status on thyroid disorders, but the effect of a transition from more than adequate iodine to adequate iodine on national changes in prevalence adjusted for changing risk factors remains unclear. Design: Two repeat nationwide surveys were conducted from 2009-2010 to 2015-2017 to assess changes in thyroid disorder prevalence and iodine status in China. Methods: A multistage stratified random sampling method was used to obtain a nationally representative sample of urban adults aged 18 and older in mainland China in 2009 (n=14925) and 2015 (n=12553). Changes in thyroid disorder prevalence, urinary iodine concentration (UIC), and thyroid-stimulating hormone (TSH) levels were assessed. Logistic regression models were used to examine changes in prevalence over time. Results: The median UIC decreased significantly from 219.7 to 175.9 μg/L (P<0.0001). The weighted prevalence of overt hyperthyroidism, subclinical hyperthyroidism, Graves’ disease, and goitre decreased between 2009 and 2015 in the overall population (P<0.05 for all). Despite no significant changes in subclinical hyperthyroidism or hypothyroidism or anti-thyroid peroxidase or anti-thyroglobulin antibody positivity prevalence, a significant increase in thyroid nodule prevalence (P<0.0001) was found in the overall population. The 2.5th TSH percentile increased by 0.15 mIU/L (95%CI, 0.01 to 0.30 mIU/L, P=0.04) from 2009 to 2015. Conclusions: With the iodine status transition from more than adequate to adequate, thyroid disorder (except for thyroid nodules) prevalence remained stable or even decreased after adjusting for confounding factors among adults in mainland China between 2009 and 2015. Additional studies are needed to explore the reasons for the increased thyroid nodule prevalence.

A Case of Exacerbation of Subclinical Hyperthyroidism after First Administration of BNT162b2 mRNA COVID-19 Vaccine

COVID-19 vaccines are the most critical measure for controlling the COVID-19 pandemic; however, we have little information on their complications. We experienced a case of a patient who developed hyperthyroidism complicated with atrial fibrillation and heart failure on the sixth day after the first dose of COVID-19 vaccination. This case report shows the importance of considering hyperthyroidism as a possible complication after COVID-19 vaccination.