Evaluation of Platelet Functions in Patients with Hashimoto's Thyroiditis Versus Healthy Controls: a Cross-Sectional Analysis.

Background: To evaluate platelet functions in patients with Hashimoto's thyroiditis (HT) versus healthy controls.

Methods: Seventy-five patients with HT and 29 healthy controls were included in this study. Age, serum levels of thyroid stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4), anti-thyroglobulin (anti-Tg) antibody and anti-thyroid peroxidase (anti-TPO) antibody, platelet count, in vitro platelet aggregation and ATP release reaction tests were recorded and compared between HT and control groups.

Results: Median (IQR) serum levels for TSH (p = 0.001), anti-TPO (p = 0.001), and anti-Tg (p = 0.001) antibodies were significantly higher, while FT4 levels (p = 0.005) were significantly lower in patients with HT than in controls. Patients had lower levels of ADP-induced platelet aggregation (p = 0.05) and lower ristocetin-induced ATP release activity (p = 0.05) compared to controls. Platelet count was positively correlated with serum FT4 levels (r = 0.27, p < 0.05). Conclusıons: We found decreased ADP-induced platelet aggregation and ristocetin-induced platelet release activity as well as a positive correlation of platelet count with FT4 levels in patients with HT. Our findings support the role of thyroid hormone status and autoimmunity in the association between HT and platelet aggregation and secretion functions.