Low t3 levels in 3rd trimester pregnancy

Am taking synthroid only 137 and latest lab has the ft4 midrange, t4 too high and t3 too low, but think endo will just want to raise t4 med to 150 and not give t3 meds. TSH is all he cares about and it it up to 1.65. Are the t3 levels dangerously low at 18 (22-35 in range?) Should I go to another DR to get cytomel or just buy it online etc?

[TamraW]

Find a doctor who treats both FreeT3 and FreeT4. T4 and T3 are obsolete. The frees are direct measurements. TSH is a pituitary hormone, NOT A THYROID HORMONE!! I'm not yelling at you, just your endo. Sheesh!!

I found my endo off this site. http://www.thyroid-info.com/topdrs/

Call ahead and ask the endo's nurse if the doc treats the symptoms and frees, and not just a TSH.

DO NOT wait. I delivered my baby 2 months early. I now know I had Hashimoto's and probably low thyroid. She is a healthy and smart six year old now, but the first few years she had delays.I'd worried she'd never catch up.

:) Tamra

[Super_sally888]

Hi,

ft3 and ft4 are the important levels in pregnancy. T4 is not useful, it represents unavailable as well as available T4.  TSH should be ignored as you are on meds.  Target is FT3 and FT4 in upper end of the range. You need your meds increased. Ideally you would also be given a t3 drug.

Thyroid levels in pregnancy are critical to your and the baby's health. It is better to slightly overtreat than undertreat. Go find another doctor, if necessary!

best wishes

[coyle]

I think We've really messed up listening to our endo and obgyn here as everything I read says what you are saying but they keep saying the t4s are what matters. I see the logic in what you are all saying. I will try to find a dr that treats ft3 levels. Thanks

[stella5349]

don't buy anything online.

[coyle]

Well, the TSH is currently 1.65 and FT4 right in the mid range. The last t3 lab was an t3 uptake that the obgyn did and the endo says it doesn't reflect t3 levels. He did give us a lab to check ft3 levels but wants us to wait almost 2 months which is close to the time we are expecting so I have no idea right now what ft3 is. What he says is the baby uses FT4 and that the medicine is converting; the TSH of 1.65 is an ok range and that everything is fine. I see his logic even though I disagree, though I also disagree with the above reply that it's better to slightly overtreat as hyperthyroidism could cause miscarriage etc. Who knows raising it from 125 to 137 brought it way down and  I think the next dose up is 150 and we wouldn't want to be  hyper and be preterm. t3 meds can probably be hyper causing and the obgyn says the baby only uses FT4. I will be making an app't with another endo in the city just to make sure but I'm starting to think perhaps this isn't that big of a deal. I've read the levels stay pretty consistent after 20 weeks.

[stella5349]

I have to disagree strongly that the baby only uses FT4. There is nothing I have ever read the makes that worth any credibility at all. In fact it is the complete false.

The mental stability of an unborn child still in the womb is based directly off the Free T3 hormones and if those are not stable - it "can" result in a mental retardation in the brain. If the body regardless of unborn or mother expecting does not have the proper Ft3 levels in it can effect both mother and child. Plus at the time of birth when you are going through it - the heart needs to be closly monitored - (which is another FT3 link) - if you are pupming too much T3 within your body and giving birth the heart can have issues during that borth.

uptake T3 tests are useless - even worse than TT3 tests

How can your doctor "prove" the med is converting w/out the lab indicating that? That's what I'd ask..

again you say this ------ "obgyn says the baby only uses FT4" - Can this OB prove that? - -- naaaa - I'm telling you - this doctor can not produce that information ligetimatly - That statement is false.

the TSH 1.65 is within a close range of being optimal for many. If you feel well at that right now then it may be fine for you.

Can you share that reading here on the stability of those levels after 20 weeks please? - I haven't read that information. What I have on file is that in the 3rd trimester the baby is developing at a rapid level - both mentally and physical - getting ready for the birth so this is a critical time to make sure you are healthy to deliver a baby safely.

[Emmy4337]

Hypothyroidism is now linked to potential pre-eclapmpsia ( Left untreated, hypothyroidism increases the risk of miscarriage, premature delivery and preeclampsia — a condition that causes a significant rise in a woman's blood pressure during the last three months of pregnancy. It can also seriously affect the developing fetus. (source mayo clinic).  I was not tested in 2004 for thyroid problems and ended up on bed rest and emergancy 36 week induction for pre-eclampsia and HELLP.  In 2006 I finally was test and TSH was 12 and had Hashimoto's so I was probably hypo while pregnant.  Some people do not convert T4 to T3 and that is where dessicated or adding Cytomel helps.  If you are undermedicated it can affect the baby.  

I would get Frees tested and find a dr. who treat based on that.

Great article on Medscape. http://www.medscape.com/viewarticle/532173_4
Part of thel Article -
"The fetus is able to produce thyroid hormones by 8 to 10 weeks' gestation, but prior to that time, is totally dependent on maternal thyroid hormones.[14] By 12 weeks' gestation, active fetal iodide trapping by the fetal thyroid gland is detectable, and the ability to produce T4 occurs shortly afterward. The fetal thyroid gland becomes operational near midgestation.[13] There is good evidence that transfer of maternal thyroid hormones to the fetus plays a critical role both before and after fetal thyroid functionality, because 30% of T4 levels found in cord blood are of maternal origin. T4 is transferred via the placenta and has been found in the gestational fluid sac of the 4- to 6-week-old fetus. Because of the low thyroid-binding properties of fetal fluid, the fetal free T4 levels are an important source of thyroid hormone and represent one third that of maternal free T4."

I did find some mention of T3 in the cord but from what I could figures out the fetus converts the T4 into the T3 it needs from it's own thyroid and uses some maternal T4 as well.  Couldn't find a clear cut answer except this and it is from 1994. http://iodine4health.com/research/burrow_1994_maternal_fetal_thyroid.pdf
graph on page 4 of this 1994 New England  Journal shows just T4 crossing over to baby.

Good luck!