Table 8.

Current findings about thyroid function in HS.

References	Type of Source	Results	Conclusion
Shlyankevich et al., 2014 [44]	retrospective case-control study (n = 1776; 1296 female and 480 male)	−smoking, arthropathies, dyslipidemia, polycystic ovary syndrome, psychiatric disorders, obesity, drug dependence, hypertension, diabetes, thyroid disease, alcohol dependence, and lymphoma were significantly associated with HS (all p < 0.01).	HS is associated with thyroid disease.
Gonzoalez-Lopez et al., 2017 [75]	case control study (n = 70; 38 female and 32 male)	−there was no significant difference between thyroid antibodies or thyroid function parameters between HS patients and controls	Autoimmunity of the thyroid gland is not involved in development of HS.
Lee et al., 2018 [45]	case-control study (n = 28,516; 11,036 female and 17,480 male)	−there was no difference in the prevalence of Hashimoto’s thyroiditis or Grave’s disease in HS (p = 0,881 und p = 0.250)	Autoimmunity of the thyroid gland is not involved in development of HS.
Miller et al., 2018 [36]	retrospective comparative cross-sectional study (n = 430; 292 female and 138 male)	−an age- and sex-adjusted analysis showed a significantly lower value (p < 0.001) for TSH and a significantly higher value (p < 0.0001) of free T3. −there was also a significant association between clinical hyperthyroidism and HS with an OR of 1.91 (95% CI 1.19–3.07; p = 0.02; adjusted for the factors BMI, smoking, and oral contraception)	HS is associated with hyperthyroidism.
Kimball et al., 2018 [70]	retrospective matched cohort design (n = 5357; 3873 female and 1484 male)	−prevalence of thyroid disease is increased (HS-mild vs. no HS: 12.0 vs. 8.6%; HS-severe vs. no HS: 12.0 vs. 7.8%) −no significant association between Hashimoto’s thyroiditis and HS	HS is associated with thyroid disease.Autoimmunity of the thyroid gland is not involved in development of HS.
Sherman et al., 2021 [72]	cross-sectional large-scale population-based study (n = 4191; 2590 female and 1601 male)	−Odds ratio for hypothyroidism was 2.91 (95% CI 2.48–3.40; p < 0.001) and for hyperthyroidism 2.25 (95% CI 1.55–3.28; p < 0.001) −association between HS and hyperthyroidism was not significant in the adjusted model.	HS is independently associated with hypothyroidism.
Liakou et al., 2021 [71]	prospective cross-sectional single-center study (n = 290; 248 female and 242 male)	−In a logistic regression model, active smoking and thyroid disease were associated with disease severity Hurley (OR 1.38; 95% CI 1.11–1.65 and OR 1.30; 95% CI 1.09–1.76) and according to the IHS4 score system (OR 1.23; 95% CI 1.09–1.64 and OR 1.42; 95% CI 1.19–1.66)	Thyroid disorders and active smoking are significantly associated with a higher HS stage.
López-Llunell et al., 2021 [73]	clinical cross-sectional study (n = 25; all female)	−a significant positive association was found between HS with vulva involvement (VHS) and fistulas (p < 0.001), acne vulgaris (p = 0.021), and thyroid disease (p = 0.006) −there was a negative association between VHS and axillary lesions (p = 0.001) −VHS patients had a later mean age of onset and a lower body mass index (BMI) (p = 0.035; p = 0.048) than those without vulvar involvement.	VHS is significantly associated with later onset, lower BMI, and thyroid disease.
Andersen et al., 2021 [74]	prospective survival analysis on a nationwide cohort of blood donors (n = 40; 23 female and 17 male)	−hazard ratio in HS has been studied based on prescribing medicines −no higher HR of antidiabetic or thyroid drugs could be detected (p = 0.084; p = 0.35) −most of the patients included had a mild course of the disease	Comorbidities (e.g., diabetes, thyroid disease) may occur first in severe disease or later in the course of the disease.