Outcome measures
Primary outcome was set to find the best LT4 + SRT3 combination to maintain normal serum concentration of TSH, T4, T3, free T4, free T3 and T3/T4 ratio. Secondary outcome was to find the best LT4 + SRT3 combination which provide most favorable T3- Cmax, T3-Tmax, and AUC and patient preferences. The study design was registered by the Iranian Registry of Clinical Trials, IRCT20100922004794N13 (dated: 08/12/2021) available at: “