How early in the first trimester should I get my thyroid levels tested?

[theflowerbee]

Doctor,

I am hypothyroid, taking 25mcg of levothyroxine.  I am now 6 weeks pregnant and wondering at what week I should have my doctor test my dosage.  I understand that it is highly likely that my dosage level will need to be increased.  I have also read that the majority of pregnant women see a change in TSH levels at about 8 weeks, but that it takes 4-6 weeks for the dose to "kick in."  During this time, will it hurt the brain development of the baby?

Thank you

[Super_sally888]

Hi,

I will have a bit different advice from stella.

The demand for thyroid hormone increases dramatically during pregnancy.  With hypothryoid and pregnancy the approach is to very agressively treat the hypothyroid to avoid any risk of development concerns with the baby.

The practice is to test as soon as you find out your are pregnant.  You should be testing TSH and FT3 and FT4.  If your TSh is high, or if your FT4 and FT3 and not in the upper end of the reference range you should increase your meds immediately.  Depending on what your levels are the dose increase would likely be 25 or 50 mcg.  A larger dose increase would only be given if your levels were really out.

However, seeing you are on 25 mcg, the likely approach would be to double it to 50 mcg and to test after 4 weeks.  Also your thyroid is obviously producing some hormone.  So although it is very important to get your levels monitored closely and your dose adjusted your baby should be fine....

During pregnancy, the practice is to test thyroid levels every 4 weeks (and adjust every 4 weeks), not every 6 - 8 weeks.  If your levels were really out they would test more frequently just to observe things are heading in the right direction and to guide any further dose increase.

When I was pregnant we tested as soon as I knew I was pregnant and increased by 25 mcg every month for the first 6 months of the pregnancy.  After that things settled down and I didn't need to increase any further.

There is more risk in being hypo than in being slightly overdosed with thyroid meds during pregnancy.

[stella5349]

It depends... you had been given meds prior to getting pregnant right? What were your labs then and have you been retested since on them - prior to getting pregnant? -

If you just happened to get pregnant after starting Levothyroxine then stick to the schedule of getting your labs redone every 6 to 8 weeks being on this med.

Most likely through mid term on this pregnancy your treating doctor for hypothyroidism may increase your medication  up to double to what you are taking now.

With this baby - you do not want to increase medication fast that could harm things more than just the hypothyroidism. Hopefully you were tested prior to getting pregnant and your medication starting making improvements prior to all this. You are on a low dose of Thyroxine - so you should be just fine.

Go slow and test your thyroid levels every 2 months regardless of the stage you are in with the baby. It's best to keep tight track on that while you are carrying this child.