Just had repeat TFT, my 2nd after commencing Levo three months ago, Am currently on 50mcg, did not take on morning (8am) of test, fasted, result back TSH 1.4 T4 12 (range 12-22), last result 6 weeks ago TSH 2.4 T4 14.2, my last pre Levo was TSH 3.4 and T4 11.4. My doc has increased me to 75mcg now, why is my TSH coming down and my T4 not rising?
Confusing Results: Just had repeat TFT, my 2nd... - Thyroid UK
Simple answer is your dose is not high enough yet.
We have to start slowly and increase in 25mcg steps. Retesting 6-8 weeks after each increase
Most patients eventually need somewhere between 100mcg and 200mcg
Important to test vitamin D, folate, ferritin and B12 as these are often too low and may need supplementing to improve
Also to know if cause of being hypothyroid is due to autoimmune thyroid disease also called Hashimoto's diagnosed by high thyroid antibodies. Ask GP to test TPO and TG thyroid antibodies if not been done already
Low vitamin levels are especially common with Hashimoto's
You’re taking levo so your tsh has come down because your body has sensed there’s more thyroid hormone in your system. But, the reduced tsh means your own thyroid gland is less stimulated and hence reduces its output of hormones. Hence the t4 level being less than you expected. Doc has done exactly the right thing and increased your levo to 75mcg.