Combined Replacement Therapy With Levothyroxine and Liothyronine in Thyroidectomized Patients

The aim of the study is to evaluate the peripheral tissue response to the combined administration of levothyroxine (LT4) and liothyronine (LT3) in hypothyroid patients with residual thyroid function virtually absent (thyroidectomized). Cases will be treated with LT4+LT3, at personalized doses according to clinical guidelines and respecting the circadian rhythmicity of LT3 and the physiological T3/T4 ratio. Controls will be treated with LT4 and placebo. Treatment duration: 24 weeks. The primary endpoint will be the peripheral effect of thyroid hormones. The secondary endpoints are bone and metabolic modifications, and changes in quality of life. Moreover any changes of outcomes related to polymorphisms of genes involved in thyroid hormones metabolism will be evaluated.