Circulating Wnt Signaling Inhibitors and Osteoprotegerin in Women with Newly Diagnosed Overt Thyroid Dysfunction

Background: Thyroid hormones influence bone metabolism, and autoimmune thyroid diseases may further impact skeletal homeostasis. Wnt signaling inhibitors, including Dickkopf-1 (DKK-1) and sclerostin (SOST), as well as osteoprotegerin (OPG), play key roles in regulating bone formation and resorption. This study aimed to evaluate circulating DKK-1, SOST, and OPG in women with newly diagnosed overt thyroid dysfunction. Methods: This cross-sectional study included 62 women with newly diagnosed, untreated overt thyroid dysfunction (35 hypothyroid and 27 hyperthyroid) and 33 age- and BMI-matched healthy controls. Serum levels of DKK-1, sclerostin, and OPG were measured using ELISA. Thyroid function and autoantibodies were assessed using automated immunoassays. Correlation analysis was performed to evaluate associations between variables. Results: Serum DKK-1 levels were significantly elevated in both hypothyroid and hyperthyroid women compared with controls (p < 0.001). Sclerostin levels showed a non-significant trend toward higher values. OPG levels were significantly increased in hyperthyroid patients and moderately elevated in hypothyroid patients. Significant positive correlations were observed between OPG and FT3 (r = 0.42, p = 0.001) and FT4 (r = 0.43, p = 0.001). In hypothyroid patients, OPG correlated positively with TgAb (r = 0.46, p = 0.007). A strong positive correlation was found between DKK-1 and SOST (p < 0.001), while DKK-1 was negatively associated with age (p < 0.05). Conclusions: Overt thyroid dysfunction is associated with significant alterations in circulating Wnt signaling inhibitors and OPG. These findings suggest a potential role of Wnt signaling and immune–bone interactions in thyroid-related changes in bone metabolism.