Levothyroxine in pregnancy

[maggie herd]

I had my Levothyroxine increased in March from 75 to 100 but found out in May that I was pregnant again. I had a consultation 3 weeks ago and they've increased my level to 150 without checking my blood and said that it was normal in pregnancy to have this medication increased.
I've been on Levothyroxine for about 6 years now, and I didn't have any increase in my second pregnancy 4 years ago and my blood levels were all within the normal range. However, this pregnancy is the worst yet. I'm tired all the time, extremely grumpy, not sleeping, and I'm getting headaches every day. My midwife appointments all show my blood pressure is fine and they're happy with my progress.
I don't know what to think, just normal pregnancy symptoms or something to do with the extra Levothyroxine. Also, I don't know if this is a coincidence but I've had a sore throat for the last 2 weeks, like there's something stuck just at the back of my tongue but I can't see anything. Anybody got any opinions?
Thanks

[Jen!]

Hi Maggie,
I have also read (in midwifery texts-I'm in a medical field) that levothyroxine requirements are increased during pregnancy. TSH can elevate (due supply not meeting demand for thyroid hormone) as early as 4 weeks into pregnancy when there is a deficiency such as hypothyroidism which was stable due to adequate medication prior to pregnancy.

It is really important for the health of your pregancy and for your health that you continue on the higher dose. It is normal for the levothyroxine dose to be increased by as much as 50% of previous non-pregnant dose.

You'd know that thyroid hormone has a lot to do with metabolism rates - well your metabolism work's overtime when pregnant. While trying to support your own metabolic needs, the body is also doing the mammoth task of constructing a baby and supplying the babies thyroid hormone requirements until it's own thyroid gland has developed and starts functioning.

I can't understand or explain why 4 years ago that your levothyroxine was not increased during pregnancy. Would it be because your blood levels were all within normal range? My only thought is that maybe then your thyroid gland (presuming it is intact) still had a little bit of function left. When taking levothyroxine over the long term the little bit of function that may be left in the thyroid gland is known to decrease over time.

I'm NO expert in this area although I wouldn't think the levothyroxine dose has anything to do with the your different experience with this pregnancy - BUT that said, please keep your midwife and OB involved especially if anything changes and causes you concern. Remember each and every pregancy can be very different.

My advice is if that feeling in your throat persists to get it checked out by a doctor to be sure there's nothing to worry about.
Best wishes with your pregnancy! Congratulations!
~Jen

[maggie herd]

Thanks for the info, I really should ask my doctor more questions at the time!
Maggie xx