Hashimotos in pregnancy - reducing thyroxine?!

[FolkSongSweet]

I’ve had hashimotos since a teenager. In my first pregnancy my dose was 175mcg (increased from 150mcg) throughout. In this one it has been all over the place 150-175-200-175-150 and now TSH is still too low so I’ve been advised to drop to 125mcg. I haven’t been on that dose since I was a teenager - it’s been stable on 150 for over 15 years. Obviously going to do it but it seems odd. Has anyone else had this?

Hmm that is odd, though would fit with roughly what I've experienced when it's well managed; bar the last drop. Usually you go back to the previous dose however from experience I actually think that if you have lactational amenorrhea you sometimes don't need as much (I've needed more when periods returned.)

When you say Hashimotos, do you mean your thyroid doesn't now work so you're entirely reliant on thyroxine or has it varied on and off?

What stage of pregnancy are you?

Are you taking any pregnancy supplements with biotin?

Are your tests at the same time each day?

What are your results each time?

Baby starts to make own thyroid hormones in the second trimester and is pretty much self sufficient by the third; you may need more because you have more blood volume; but everyone is different.

Tsh needs to be below 2.5 in first trimester but can be up to 3 in last two.

I can reassure you that baby will be absolutely fine as I had a nightmare with my first and he's now happily running around at school.

If you're normally on 150 and they want you to go to 125; that's what I'd query.

Thanks so much for the reply @NeurotrashWarrior.

I was diagnosed with Hashimotos at 16 and haven’t actually seen a consultant since then - just managed it through my GP and apart from in my last pregnancy (when I increased to 175 in the first trimester and stayed there til about 3 months post partum) I’ve been on 150mcg the entire time - 17 years now! No idea whether my thyroid has totally packed in or just has remained stable at lower levels.

I’m now 33 weeks. At 20 weeks I was on 200mcg and TSH was too low (can’t remember exactly but under 0.3), so I reduced to 175. At 28 weeks I was retested and it was 0.13 so reduced again to 150 (my pre-pregnancy dose). At 32 weeks TSH was 0.22 so still too low, so I’m being advised to drop to 125, which I haven’t been on since first diagnosed. It’s very odd!

Tests have been in the morning each time - usually see the midwife between 10 and 12.

Oh and I’m not taking any supplements other than vitamin D, and need to take iron tablets soon as also anaemic.

Ok that's fine, you are actually being well managed. It's very hard to know with thyroids; it's very possible you have some tiny bit of residual function that's kicked in during pregnancy; who knows!

In "normal" women the thyroid swells in response to hormones to accommodate the extra needs of the pregnancy, and naturally reduces as necessary. Apparently that's how ancient Egyptians knew they were pregnant; when a band around their necks became tighter (you'd have thought the puking be a clue though!)

So who knows if that's what has happened, or something to to with less anntibodies?? Thyroid stuff can be a mystery!

You could ask for a repeat test at 36/38 weeks or suggest that you do 3 150s and 4 125s a week? Or both? Tsh around 1 would be great but ok up to 3 (you just may feel a bit tired.)

It's wise to get a test around 6 weeks after birth (check the btf website, really comprehensive info.)

Biotin (a b vitamin) can interfere with results so you tend to have to stop taking it for a week before a test.

www.btf-thyroid.org/thyroid-disorders-and-pregnancy

And good luck with the rest of your pregnancy!

Thanks so much @NeurotrashWarrior - very reassuring! I know some hospitals treat pregnant women with thyroid issues as high risk/consultant led, but mine doesn’t. I think my midwife has emailed the consultant endocrinologist though so will see what they say.