Hypothyroidism is a common condition, more frequent in females, associated with excess of cardiovascular risk and poor quality of life not completely abrogated by treatment with levothyroxine. There is an unmet need to define a safe, effective, and feasible regimen to be applied in large trials aimed at assessing levothyroxine/liothyronine combination therapy in patients living with hypothyroidism. To address this knowledge gap we propose a randomized, three-arm, double-blind, controlled, escalating dose parallel pilot study whose results will lay the foundation of large multicenter trial(s) able to demonstrate the effectiveness (or lack thereof) of levothyroxine/liothyronine combination therapy.