Planning pregnancy,tsh was 3.40 after having thyronorm 25mg fr 1 mnth tsh becomes 4.10. y it happened? how much mg is needed to get to the level 2.50

Speak to your doctor: It may be that you're not getting enough thyronorm and your dose needs to be increased which seems more likely. It may take 1-3 months for the TSH level to go down, but should have been coming down if you've been taking it regularly for the past month. I suggest to talk to your doctor who has done the initial workup about adjusting your dose.