Table 6.

Summary of studies related to thyroid eye disease included.

First Author	Years	Country	Study-Design	Sample Size	Main Finding	Rate #
Ama Sadaka [245]	2019	United States	Retrospective study	35 TED patients	20% and 31% prevalence of vitamin D deficiency and insufficiency were found in TED, respectively.	4a
Curtis J Heisel [246]	2020	United States	Retrospective case-control study	89 TED patients (TED), 89 GD patients without TED (GD), and 2 healthy control groups matched 4:1 to the cases; 356 healthy control patients matched to the TED group (HC TED), and 356 HC patients matched to the GD (HC GD)	Low serum vitamin D is associated with TED diagnosis. Assessing and supplementing vitamin D levels may be an important addition to the early management of GD patients.	4a
Tereza Planck [247]	2018	Sweden	Cross sectional study	Epidemiological part—292 GD patients and 2305 healthy controls Clinical part—219 GD patients Relapse analysis after antithyroid drug treatment part —100 GD patients Genetic part—708 GD patients with (n = 245) or without (n = 459) ophthalmopathy and 1178 sex-matched controls	Patients with GD had lower vitamin D levels compared to the general population; however, the vitamin D levels did not affect the laboratory or clinical parameters of GD. SNPs in the VDR influenced the risk of GD through mechanisms other than reducing the vitamin D levels.	4a

Thyroid eye disease (TED), Graves’ disease (GD); # LEGEND for case-control, cohort, and cross-sectional studies, rating of the studies follow the guidelines from LEGEND.