TSH was 7.21. Synthroid (thyroxine) increased from. 1 mcg/day to. 1 mcg x 6 days and. 150 mcg 7th day. Can TSH decrease to 4 in 2 weeks of treatment?

Feasible. It may decrease as you described. It is generally not a good idea to aim for too fast a change as it takes a few weeks for the system to come to a balance on change of dose.