Endocrine Abstracts

Introduction: Despite normal thyroid stimulating hormone (TSH) serum levels, 10% of hypothyroid patients treated with LT4 complain of hypothyroidism symptoms, likely linked to decreased availability of free triiodothyronine (fT3). Thus, combined levothyroxine/liothyronine (LT4/lT3) therapy was suggested to ensure a more physiological balance in peripheral tissues.

Aim: To evaluate the effectiveness of combined LT4/lT3 therapy in thyroidectomized subjects, considering peripheral markers and quality of life.

Methods: An interim analysis of a prospective, randomized, placebo-controlled, double-blinded clinical trial was performed. Totally thyroidectomized patients treated with LT4 and with TSH levels within reference range in the previous three months were enrolled and randomized in two groups: combined LT4/lT3 therapy (study group) and LT4+placebo (control group). Lipid profile, sex hormone binding globulin, osteocalcin, C-terminal telopeptide and bone alkaline phosphatase were evaluated as peripheral markers. Quality of life was evaluated by ThyPRO 39 questionnaire.

Results: 139 patients (age 55.6+12.1 years) were enrolled, 70 in the study and 69 in the control group. Combined LT4/lT3 therapy resulted in more frequent iatrogenic thyrotoxicosis than LT4 monotherapy (9.8% vs 2.2%; P < 0.05), requiring more frequent dose adjustments (44.5% vs 22.5%; P < 0.001). Peripheral markers neither changed between study and control groups, nor among visits. Combined therapy improved quality of life, measured by a reduction in anxiety (P = 0.019), depression (P = 0.037), emotional susceptibility (P = 0.034) and item 12 (P = 0.005) from baseline to visit 3, while no significant differences were detected in controls.

Conclusion: Six months of combined therapy significantly improved quality of life, but did not lead to a change in peripheral tissue markers. However, subjects treated with LT4/lT3 therapy require more dose adjustment and are at higher risk of overtreatment.