Underactive thyroid and over medication

[Spottybluepyjamas]

Hi all,

I recently found out that I'm pregnant (very early, just 4 weeks). I have an underactive thyroid and am usually on 100mg per day levothyroxine.

In my previous pregnancies I had the dose increased by 25mg each time (no blood tests done), but unfortunately miscarried twice.

This time, the doctor spoke to an endocrinologist who recommend an increased of 50mg (150 total vs my usual 100). Again, this is without having a blood test. My blood test is due soon, but I've been advised to start the increased dose now.

I want to follow the doctor's recommendation, but I'm worried about any damage that might occur if it's an over medication.

I don't want to google, because Im sure it will terrify me, but does anyone know if the dangers of over medication are as dangerous/worse than under medication of levothyroxine during pregnancy?

Thank you so much.

It's unlikely to take you into hyper as your thyroid demands increase from week 5 and your levels are presumably stable round the 1-3 level? It's been shown to be important to keep you under 2.5 in the first trimester.

If you do notice some strange things starting, surely it's safer to titrate your medication down than have the consequences of your levels going to high (ie potential miscarriage).

I swear I read that if you were on 100 micrograms or more you should increase by 50. Unfortunately can't find the link!!!

Thank you @physicskate 😊 I just find the whole thing stressful, especially when it's a bit of trial and error to get the meds right!

I've definitely always thought I can tell if I'm over medicated (I feel jittery, can't sleep as well, etc). I've had to increase by 75mg so far (I'm 14 weeks... increased by 4 weeks, normal TSH at 8 weeks, then high again at 11 weeks and increased again by 25mg). If anything, I've felt under medicated (tired and cold). I think you'll know if you're off by a long way, either too much or too little.

When I found out I was pregnant I tested my TSH levels and they were so low that none was detected. I had to repeat the test and again, none (or rather too low to be detected, less than 0.0005 or something). I think I had been on a dosage higher than necessary at the time and I could feel it as pp said - jittery, problem sleeping, heart racing etc. But this didn't influence my pregnancy. I readjusted the dose and everything was fine. So do not worry, increase the dose as the doctor said (unless you feel the symptoms mentioned) and then wait for your test results to see if further changes are needed.

I was told earlier in the week by my GP that they increase it by 25% but honestly they didn’t increase it for me in my first pregnancy (and I didn’t know enough to question that decision), and I felt so drastically unwell until it finally got sorted. I’d rather take more than less, and like someone else said you can then titrate it down. Congratulations!