Discriminatory value of carotid artery elasticity changes for the evaluation of thyroid dysfunction in patients with hashimoto's thyroiditis

Arterial Stiffness in Thyroid and Parathyroid Disease: A Review of Clinical Studies

Growing evidence shows that arterial stiffness measurement provides important prognostic information and improves clinical stratification of cardiovascular risk. Thyroid and parathyroid diseases are endocrine diseases with a relevant cardiovascular burden. The objective of this review was to consider the relationship between arterial stiffness and thyroid and parathyroid diseases in human clinical studies. We performed a systematic literature review of articles published in PubMed/MEDLINE from inception to December 2021, restricted to English languages and to human adults. We selected relevant articles about the relationship between arterial stiffness and thyroid and parathyroid diseases. For each selected article, data on arterial stiffness were extracted and factors that may have an impact on arterial stiffness were identified. We considered 24 papers concerning hypothyroidism, 9 hyperthyroidism and 16 primary hyperparathyroidism and hypoparathyroidism. Most studies evidenced an increase in arterial stiffness biomarkers in hypothyroidism, hyperthyroidism and primary hyperparathyroidism, even in subclinical and mild forms, although heterogeneity of measurement methods and of study designs prevented a definitive conclusion, suggesting that the assessment of arterial stiffness may be considered in the clinical evaluation of cardiovascular risk in these diseases.

Meta-analysis on the association between thyroid hormone disorders and arterial stiffness

Context

Aortic stiffness is an emerging predictor of cardiovascular morbidity and mortality. Current data about the effect of subclinical and overt thyroid hormone disorders on aortic stiffness are often conflicting.

Objective

Primary outcome was to investigate if subclinical and overt thyroid hormone disorders were associated with aortic stiffness. Secondary outcome was to identify disease effect modifiers.

Methods

Data sources were PubMed, Google Scholar, SCOPUS, Web of Sciences, and the Cochrane Library. Eligible studies included reports of pulse wave velocity (PWV), which is the gold standard method for measuring aortic stiffness, in patients with subclinical and overt thyroid disorders. Two investigators independently identified eligible studies and extracted data. Pooled mean difference was the summary effect measure. Data were presented in forest plots with outlier and influential case diagnostics. Univariate meta-regression analysis was used to identify effect modifiers.

Results

Eleven observational studies were selected, including 1239 patients with subclinical hypothyroidism, 81 patients with overt hypothyroidism, 338 patients with thyrotoxicosis, and 12 715 controls. PWV was significantly higher in subclinical (P < .001) and overt hypothyroidism (P < .001), as well as in patients with thyrotoxicosis (P = .027) compared with controls. Age was an effect modifier in hypothyroid patients.

Conclusion

This study shows that both overt and subclinical hypothyroidism as well as thyrotoxicosis were associated with an increase of aortic stiffness. The impact of treatment of these conditions on aortic stiffness should be assessed in clinical trials.

The role of thyroid hormones in carotid arterial wall remodeling in women

INTRODUCTION

Thyroid hormones affect the cardiovascular system, but the precise mechanisms of their effects on the development of atherosclerosis are not entirely clear. The relationship between subclinical hypothyroidism, dyslipidemia and carotid atherosclerosis has been widely investigated, but the findings were controversial. The aim of the present study was to determine whether female subjects with subclinical hypothyroidism (SHypo) have increased carotid intima-media thickness (IMT) compared with euthyroid subjects, as well as to examine the association of SHypo, carotid atherosclerosis and dyslipidemia.

METHODS

This research included 100 women aged 30 to 70 years who were divided into two groups: the SHypo group including subjects with signs of subclinical hypothyroidism and the control group of euthyroid subjects. Carotid IMT thickness using B mode ultrasound was determined and its correlation with serum concentrations of fT4, TSH, CRP, and lipid profile including small dense LDL (sdLDL) was analysed.

RESULTS

Subjects with SHypo had significantly increased carotid IMT (IMT ≥ 75th centile) in all three measured segments of the right (p <0.001) and the left (p = 0.001) carotid artery compared to the control group, with a significantly more frequent appearance of plaque (25% vs. 9%; p = 0.05). Significant positive correlations were found between higher TSH and higher IMT values. Increased age, LDL cholesterol, and TSH predicted thickening of the carotid artery IMT.

CONCLUSIONS

It is important to screen people showing early, subclinical signs of thyroid gland dysfunction due to its impact on carotid atherosclerosis development.

Thyroid Dysfunction and Atherosclerosis: A Systematic Review

BACKGROUND/AIM

Thyroid dysfunction, both hypo- and hyperthyroidism, has been associated with cardiovascular disease. The aim of this study was to evaluate the association between thyroid dysfunction and atherosclerosis measured mostly by carotid intima-media thickness, as well as discuss whether L-T4 replacement is able to reverse or slow down the progression of atherosclerosis.

MATERIALS AND METHODS

The review was conducted according the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. We performed on PubMed a literature search from May 2004 to January 2020, using the search terms 'subclinical hypothyroidism' or 'thyroid disorders' and 'carotid artery', 'carotid intima-media thickness (IMT)', 'levothyroxine', and 'atherosclerosis'.

RESULTS

Twenty-six studies were eligible and included in the analysis. Overall, the studies encompassed a total of 36.434 patients included in this review. Most studies indicated a proportional correlation between IMT and thyroid dysfunction. Levothyroxine (L-T4) replacement led to significant decrease of IMT after 1 year in most studies.

CONCLUSION

Most studies have concluded that thyroid dysfunction is associated with arterial wall remodeling and, thus, with increased cardiovascular risk. However, the exact mechanistic background of pathological structural changes in the arterial wall is still unsettled. Large randomized controlled studies are required to definitively address the extent to which T4 replacement therapy might benefit patients with subclinical thyroid disorders.

Subclinical hypothyroidism is associated with higher carotid intima-media thickness in cross-sectional analysis of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

BACKGROUND AND AIM

Although subclinical hypothyroidism (SCH) is associated with cardiovascular risk, there is scarce data about subclinical atherosclerosis in subjects with SCH. We aimed to analyze the association between SCH and carotid intima-media thickness (IMT) using baseline data from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

METHODS AND RESULTS

We included subjects with normal thyroid function (TSH: 0.4-4.0 mIU/l, and normal free thyroxine (FT4): 0.8-1.9 ng/dl) and SCH (TSH ≥ 4.0 mIU/l and normal FT4) evaluated for IMT in a cross-sectional analysis. We excluded individuals using medications that affect thyroid function and those with a history of cardiovascular disease. We performed logistic and linear regression models to evaluate the association with IMT (mean values and categorized at the 75th percentile) as a dependent variable and SCH as an independent variable, adjusted for other cardiovascular risk factors. From 8623 subjects (median age of 50 years; interquartile range: 44-57), 4624 (53.6%) were women, 8095 (93.9%) were euthyroid, and 528 (6.1%) had SCH. Groups varied in age, body mass index, Framingham risk score, Homeostasis Model Assessment for Insulin Resistance (HOMA-IR), C-reactive protein, as well as, IMT, that were all higher in SCH compared to euthyroid participants. SCH is associated with IMT as a continuous variable (β = 0.010, P = 0.036) and IMT >75th percentile: OR = 1.30 (95% CI = 1.06-1.59) in logistic models.

CONCLUSION

Individuals with SCH presented higher IMT compared with euthyroid subjects, even after adjustment for potential confounders. IMT was independently associated with SCH in the baseline of the ELSA-Brasil study.