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Thyroid UK
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New test 4 weeks, too soon?

Thank you all so responded to my previous posts, it had helped me a lot.

I have started 25mcg levothyroxine 2.5 weeks ago. Haven't seen any improvement yet. Will take new blood tests soon. I just wonder if it would be too soon to have then done after 4 weeks on levo? Since I am feeling rubbish I'm eager to feel better and therefor I would like to have them done as soon as possible.

My results were(without any medication) :

Tsh 5.62 (0.4-5.5)

Ft4 12. 1 (10-19.8)

Ft3 3.5 (3.8 -)

TPOab 40 (<60)

5 Replies


It will have taken 7-10 days for the Levothyroxine to be absorbed so it will only have started to work a few days ago.

4 weeks is premature for testing. Testing 6-8 weeks after starting Levothyroxine will show how your blood levels have responded. Arrange an early morning and fasting (water only) blood draw and take Levothyroxine after the blood test.


Ok, thank you very much for your kind reply.


25mcg of levo is a low starting dose and the usual is 50mcg with 25mcg increases every six to eight weeks till symptoms are resolved. That's maybe why you haven't yet felt an improvement. Unless of course your doctor treats the blood tests only and not how the patient feels with symptoms.

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Thank you for your kind reply. Is it common to feel better and better along the way to your preferred dose?

I just read the leaflet that comes with the medicine and it said that you should have another test after 4 weeks to see the levels in your blood.


Unfortunately its not that easy. I felt far worse when I took levothyroxine and I was pretty unwell before that.

Normally, I believe that most on levothyroxine as their dose increases the better they can become. It's because we are dealing with 'hormones' rather than medication our whole system is affected not just one part and we are all so different in what suits us, i.e. dose wise.

It may say 4 weeks on your leaflet but the norm is 6 weeks and some doctors say 8 weeks.

I hope you feel better soon.

Remember blood tests are at the very earliest and fasting. You can drink water and allow 24 hours approx from last dose of levo and test and take it afterwards.

If GP hasn't tested Vit B12, Vit D, iron, ferritin and folate ask for these to be done as we are usually deficient and can make a big improvement when optimum.


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