IRCT201406299014N38 IRCT 2014-07-04 Vice-chancellor for Research the Technology, Hamadan University of Medical Sciences Effect of fasting versus bedtime levothyroxin on primary hypothyroidism Effect of fasting versus bedtime levothyroxin on primary hypothyroidism: A randomized clinical trial 2014-07-23 anticipated 50 Complete https://irct.ir/trial/9477 interventional Randomization: Randomized, Blinding: Not blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Other design features: Randomization: Using block randomization with group of four so that every four patents will be randomly assigned to either intervention or control groups. This process will be continued until to reach the sample size. Blinding: The type drug in intervention and control groups is the same but the time of using drug is different. Since, blinding the time of drug usage is impossible. Therefore, the trial will be run as open label. 2 primary hypothyroidism. Intervention 1: Oral levothyroxine 1.6 mcgr per kg before sleep for 8 weeks. Intervention 2: Oral levothyroxine 1.6 mcgr per kg half an hour before breakfast for 8 weeks.