Quality of Life and Mood in Relation to Free T3, Free T4 and the FT3/FT4 Ratio in Levothyroxine-Treated Hypothyroidism: A Cross-Sectional Study

Background and Objectives: Many levothyroxine (LT4)-treated hypothyroid patients report persistent symptoms. We examined thyroid-related quality of life (QoL) and anxiety and depression symptoms in LT4-treated patients with Hashimoto thyroiditis or after thyroidectomy, and their associations with free triiodothyronine (FT3), free thyroxine (FT4), the FT3/FT4 ratio and thyrotropin (TSH). Materials and Methods: In this single-centre cross-sectional study, 219 consecutive adults (63 clinic comparison participants without known thyroid disease, 110 LT4-treated Hashimoto patients and 46 LT4-treated post-thyroidectomy patients) completed a Turkish ThyPRO short-form version (nine scales plus an overall QoL-impact item) and the Hospital Anxiety and Depression Scale (HADS). Fasting blood was drawn before the daily LT4 dose. Linear models were adjusted for diagnostic group, age, sex, body-mass index and TSH, with ratio × group interaction testing and group-specific slopes.