Association between thyroid function and disease severity in restless legs syndrome

Chaofan Geng; Zhenzhen Yang; Xiumei Kong; Pengfei Xu; Hongju Zhang

doi:10.3389/fneur.2022.974229

Association between thyroid function and disease severity in restless legs syndrome

Front Neurol. 2022 Aug 12:13:974229. doi: 10.3389/fneur.2022.974229. eCollection 2022.

Authors

Chaofan Geng¹, Zhenzhen Yang², Xiumei Kong³, Pengfei Xu¹, Hongju Zhang^{1

4}

Affiliations

¹ Henan University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, China.
² Fuwai Central China Cardiovascular Hospital, Henan Provincial People's Hospital, Zhengzhou, China.
³ Henan University Joint National Laboratory for Antibody Drug Engineering, Kaifeng, China.
⁴ Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China.

Abstract

Background: Restless Legs Syndrome (RLS) is a common neurological disorder. Growing evidence shows that dopaminergic dysfunction and iron deficiency are associated with the pathogenesis of RLS. Additionally, the dopaminergic system is linked with the hypothalamic-pituitary-thyroid (HPT) axis. Thus, the current study aimed to compare thyroid function between RLS patients and healthy subjects and investigate the associations with clinical characteristics of RLS.

Methods: Serum levels of thyroid hormones were investigated in 102 first-episode drug-naïve RLS patients and 80 matched healthy controls (HCs). Baseline data and clinical characteristics were performed by professional personnel. In addition, multivariate regression was used to analyze the relationship between thyroid function and RLS.

Results: Compared with control group, RLS patients had significantly higher serum thyroid-stimulating hormone (TSH) levels (p < 0.001), and higher prevalence of subclinical hypothyroidism [Odds ratio (OR) 8.00; 95% confidence interval (CI) = 3.50-18.30; p < 0.001]. The Subclinical hypothyroidism rate (47.1 vs. 10%, p < 0.001) in RLS patients was higher than the HCs group. Regression analysis revealed that serum TSH (OR = 1.77; 95% CI = 1.41-2.23; p < 0.001) was independently associated with RLS. There was a statistically significant positive correlation between TSH and the Pittsburgh sleep quality index (PSQI) scores (r = 0.728, p < 0.001), and the International Restless Legs Scales (IRLS) points (r = 0.627, p < 0.001). Spearman correlation analysis showed that FT₃ was positive correlated with HAMA₁₄ score (r = 0.239, p = 0.015). In addition, compared with the good-sleeper group, poor-sleeper patients had significantly higher serum TSH levels (p < 0.001).

Conclusion: Serum levels of TSH and the prevalence of subclinical hypothyroidism were higher in RLS patients, indicating the imbalance between thyroid hormones (TH) and the dopaminergic system may contribute to the development of primary RLS. Additionally, the TH axis may influence the quality of sleep in RLS patients.

Keywords: FT3; FT4; TSH; restless legs syndrome; sleep disorder; thyroid dysfunction.