Endocrine Abstracts

Background and objective: Sleep disorders (SDs) are classified into subjective and objective SDs, and subjective SDs are directly related to quality of life. According to previous studies, Graves’ disease (GD) causes SDs, especially insomnia. However, the characteristics of subjective SDs and its clinical course after hyperthyroidism normalization remain unclear. Additionally, the factors involved in subjective SDs with hyperthyroidism in GD remain unclear. Hyperthyroidism is involved in sympathetic activity (SA). SA is likely to correlated with SDs. This study aims to evaluate the characteristics of subjective SDs and its clinical course after GD treatment, and to clarify the factors involved in subjective SDs associated with hyperthyroidism.

Methods: A prospective study with a substudy that involved cross-sectional analysis at baseline to evaluate the relationship thyroid function and the characteristics of SDs was perfomed. 72 participants (22 newly diagnosed with GD with untreated hyperthyroidism, 20 previously diagnosed with GD with normal thyroid function, and 30 normal controls) with no other underlying SD-related diseases were enrolled from November 2017 to October 2020. We compared the groups at enrollment and conducted prospective observations after 12 months of treatment on participants with newly diagnosed GD. Subjective SDs were assessed by differences and changes in the Pittsburgh Sleep Quality Index (PSQI) global and component sleep quality scores. SA was assessed by pulse rate and urinary metanephrines.

Results: Free thyroxine (FT4) level, pulse rate and urinary metanephrines were significantly higher in untreated hyperthyroidism group compared to other group (P< 0.05). FT4 level was significantly positive correlated with pulse rate (r = 0.643, P< 0.001) and urinary metanephrines (r = 0.387, P< 0.001). PSQI global sleep quality scores (P=0.036) and sleep disturbance scores (P=0.011) were significantly different among the three groups, and were highest in the untreated hyperthyroidism group. Multiple regression analysis demonstrated that FT4 level was associated with poorer PSQI global sleep quality scores independently of other factors (P=0.006). Prospective observation in 18 untreated hyperthyroidism group showed that FT4 (P< 0.001) and SA such as pulse rate (P=0.002) and urinary metanephrines (P< 0.001) significantly improved by therapeutic intervention. PSQI global sleep quality scores (P=0.047) and sleep disturbance scores (P=0.007) significantly improved.

Conclusions: Hyperthyroidism in GD caused subjective SDs, especially sleep disturbance. SA due to hyperthyroidism may contribute to subjective SDs. Treatment for hyperthyroidism and SA may improve subjective SDs.