Underactive thyroid- third trimester- TSH 3.6

[katpw]

Hello,

I’m 37 weeks pregnant and my TSH result came back at 3.6 following a blood test last week.

My result in January was 1.63.

I called the endocrinologist who said ‘normal’ is up to 5 and wasn’t concerned whereas google tells me otherwise and that a max of 2.5 is suggested.

Should I be worried? Petrified for my baby and what it means for them?

The only other thing I can think of is I took my Levothyroxine a few hours before the blood test (baby brain!) whereas I normally take it after- could that have majorly skewed the result?

Thank you so much.

Now worrying even more so as taking Levothyroxine before would actually make the result lower if anything, not higher..

The effect of Levothyroxine is cumulative and usually takes about 4-6 weeks to make a difference to your TSH. You should be taking it in the morning at least 30 mins before food or drink (especially caffeine), an hour is better.

were you on Levothyroxine before your pregnancy? What dosage are you taking? Was your dosage increased?

I have hypothyroidism and my midwife is aiming to keep my TSH at 2.0 or below (previous pregnancy was 2.5). Unfortunately TSH up to 5 (and above in some cases) is considered “normal”. I would contact your midwife and ask if they are ok with your TSH being above 2.5. I’m not sure at 37 weeks they would change your dosage as it takes weeks to take effect and I suspect you’ve been told to lower/ stop taking it after birth?

Thanks @Happycroc

Yes have been on Levothyroxine for a number of years. Was on 75mg before pregnancy and for majority of pregnancy have been on 75mg for 5 days a week and 100mg the remaining 2 days.

I spoke to my midwife as said I was concerned but she suggested speaking with endocrinology- who said up to 5 is normal..

As a first time mum and generally anxious person, I am so worried and not sure whether to trust their reassurance? So much research online makes me feel 3.6 is too high.

I don’t want it to be risking the health of our baby but not sure what I can do?!

Thank you.

Don’t quote me on it but I think that elevated (above 2.5) TSH is more of a concern in early pregnancy. Mine has steadily increased during this pregnancy, last blood test came back at 2.0 whereas it was about 1.1 at 12 weeks, I don’t have any more blood tests booked. TSH does naturally increase with pregnancy and I suspect that the large majority of woman would not know what their TSH is and many would be unknowingly above 2.5.

I might be tempted in your situation to just increase my Levothyroxine to 100 a day for the last few weeks but remember to drop to your pre pregnancy dosage after delivery and make sure they do your bloods at your 6 week check up, I wasn’t told to do this in my last pregnancy and ended up with a TSH of 0!

www.markvanderpump.co.uk/blog/posts/what-do-the-results-of-my-thyroid-test-mean

This is taken from the website of a private endocrinologist in London specialising in thyroid disorders. It has a section about normal ranges in pregnancy- for a woman in 3rd trimester it is normal up to 5. X

@katpw just had a thought, you’re not taking your levo at the same time as a pregnancy vitamin are you? I believe that it can also hinder absorption so I take each at either end of the day