Lab results on NDT - pregnant

Hello, I have been following this community for a while but this is my first post.

I have been self treating with NDT for 2.5 years after having problems with infertility (tsh 4.5 was over the 2.5 recommended for ttc but right at the top of the typical range) having low t4 and t3 and not being able to find a physician to treat it. I’ve been taking Thyroid-S 4 grains, have felt great and I was finally able to conceive after 4.5 years of trying. I’m 6 weeks along right now. My OBGYN did labs at 5 weeks and was very concerned that my tsh came back at .005 - she wouldn’t run free t4 or free t3 so I ordered it on my own at a local lab. I know that NDT suppresses tsh so I wasn’t too concerned but I wanted to double check that my free t4 wasn’t too high now that I’m pregnant. I stopped taking my NDT for 4 days before my labs just in case I was taking too much and hurting the baby.

Here were my independent lab results:

tsh: .006 (.45 - 4.5)

Free T4: 1.25 (.82 - 1.77)

Free T3: 2.7 (2.0 - 4.4)

I assumed my FT3 would be low since I hadn’t taken any T3 in 4 days.

Otherwise, how do my labs look? do you think I am okay on my current does of 4 grains? I plan to repeat labs every 4 weeks throughout the first half of pregnancy.

Thanks in advance for your help!

8 Replies


You've skewed the results by not taking NDT for 4 days prior to the blood draw. You need to leave a maximum of 12 hours between last dose and blood draw.

Hard to say whether you are overmedicated on 4 grains because FT3 will have dropped without T3 for 4 days. I think FT4 is unlikely to have dropped much in 4 days.

Yes, I was afraid of that. How does the FT4 look to you? I know it’s half life is much much longer than FT3


FT4 is just under halfway through range which is fine for someone taking NDT.

TSH is very suppressed but as far as I'm aware it is high TSH and low FT4/FT3 which are problematic during pregnancy, not low TSH.

Great. That matches up exactly to everything I have researched. I will continue on 4 grains and retest in 3 weeks or so. I’ve read that pregnancy puts more pressure on thyroid so an increase in meds is usually required at some point. Seems that FT4 is more vital to the baby than FT3, which is more vital for the mother feeling well.


Yes, the foetus is dependent on maternal hormone until 12 weeks. In the UK Levothyroxine dose is usually increased by 25-50mcg when pregnancy is confirmed. That would be roughly 1/2 to 3/4 of a grain.

Thanks for that info! It may be beneficial to raise up until my next labs and see how I feel. I’ve really always based my dose on how I’m feeling and have had great success with that but being pregnant has made me rather paranoid ha


I really wouldn't increase dose. TSH is supressed and FT4 good which indicates you are optimally dosed already.

Okay! I will just keep an eye on everything. Thank you!

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