Hi, I was looking for some advice. I am 7 weeks pregnant through IVF, and I am hypothyroid. In July my TSH was 0.67, yesterday my TSH result was 4.19 with a T4 reading of 22 (which was within range)
I have read all the pregnancy advice re: upping dose when pregnancy confirmed but was advised by clinic to wait for blood test at first scan. I have now been advised to up my meds from 100mcg to 125mcg, does this sound right and how long does it take to lower levels ?
I plan to have a private test for vitamins and full thyroid results including antibodies
Ah, I see. Answering that with any reliability is going to be difficult. TSH rarely moves quickly.
But...
1) TSH isn't the thing that a baby needs in the early days of pregnancy and before it grows a thyroid.
2) What it needs is adequate levels of Free T4 and Free T3. Free T3 is the active thyroid hormone.
3) The reason that TSH is measured and used as a yardstick for thyroid hormone levels in pregnant women is because doctors think that the levels of the actual thyroid hormones are irrelevant and only TSH counts. And that is true for all of us - male, female, pregnant, not pregnant.
4) Note that doctors think that T3 is actually dangerous for growing babies, which is the most absurd tripe I've heard in this context.
5) TSH might or might not move quickly. But thyroid hormone levels do move quite quickly, so if you have raised dose that is probably the most important thing.
I agree with humanbean , 2.5 is the maximum, not the recommended level. Some people are still quite ill with a TSH of 2.5. Although, it's not the TSH that causes the symptoms, that's down to low T3. But, it's T4 that crosses the blood/placenta barrier, and you appear to have plenty of that, so that's good. You're probably a poor converter, and that's why your TSH is high, but you won't know without having your FT4 and FT3 tested at the same time and comparing them.
Generally the higher the TSH the quicker the response to added thyroxine and usually a 6 week wait is seen as adeqaute for levels to restabalise before testing. However, because you are pregaant you are not waiting for the total cell saturation that the usual recommended six week blood test determines but an immediate TSH blood serum level of low-normal range (0.4–2.0 mU/L) and an FT4 concentration in the upper reference range which you already have but must be maintained.
Women with known thyroid dysfunction who are taking levothyroxine may need the dose increased by 30–50% from as early as 4–6 weeks gestation. [De Groot et al, 2012].
Your FT4 levels are fine as although high will be needed for supporting baby who has no thyroid gland of his own for about 12 weeks. Ensure your GP doses you on TSH which must be kept low to ensure no early rising of prolactin that can encourage pregnancy complications.
NICE states that your doctor must discuss urgently with an endocrinologist regarding initiation of or changes to dosage of Levo while waiting for a review. Blood tests should be performed every four weeks during the first trimester, then 16 and 28 weeks of gestation, or more frequent if needed.
Ignore the 'T3 debacle' below as you are only medicating Levothyroxine (& not T3), so as such during pregnancy only TSH & FT4 became the main perimeters for dosing.
The recommendation is TSH below 2.5 in the first trimester and below 3.0 in the second and third trimester. Little T3 crosses the placenta so T4 levels are more important. BUT. Patients who are on high doses of L-T3 have very low fT4 but usually have normal pregnancies. This is an enigma, the two facts seem to be in conflict.
The recommendation re TSH is because studies compared pregnancy outcomes against TSH.
You may find your TSH goes too low on 125 mcg but it will be easy to adjust your dose if this happens. I’m not a doctor but I think you are well clear of levels that might cause concern.
BUT. Patients who are on high doses of L-T3 have very low fT4 but usually have normal pregnancies. This is an enigma, the two facts seem to be in conflict.
Couldn't that possibly be because women on high doses of L-T3 don't need the T4 for conversion, so it all goes to the baby?
Yes, but research shows that very little T3 crosses the placenta, it is converted to T2 by type-3 deiodinase. This leads many endocrinologists to state that T3 cannot cross the placenta but this is clearly not true because millions of healthy babies have been born with low T4 levels. This was the norm before levothyroxine was was manufactured and patients were on natural dessicated thyroid.
Apologies, I’m leading us into a technical discussion which may confuse. The bottom line is T4 is believed to be important for the early stages of pregnancy but for reasons we don’t understand many mothers and babies do well with low T4 provided there are high levels of T3.
Feel free to ignore this if it’s confusing or you’re not interested!
Well, yes, we know all that - at least, we've heard it. It's like the theory that T3 doesn't cross the blood/brain barrier but obviously does. Could be it's more a question of preference rather than a hard and fast requirement. But, you completely side-stepped my suggestion. Never mind...
Sorry, didn't mean to side-step you suggestion, was just a bit dozy! I feel pretty sure that the T4 isn't diverted to the baby because when we measure the T4 or fT4 in the blood it is very low and these low doses cause cretinism - except when fT3 is high.
The brain gets about 80% T3 from converting T4 and 20% T3 from the blood. (this is based on animal experiments). So, T3 does cross the blood brain barrier but is transported to a lesser extent than T4. This is why I argue that if someone has impaired conversion as evidenced by low normal fT3 it will not be sufficient to just restore normal fT3 levels with a little liothyronine, this just restores the 20% T3 that is coming from the blood.
Trouble30 please excuse us, this is how we learn. You TSH is a little high but you have plenty fT4 and as I noted earlier this is fine tuning and things should settle down in a few weeks.
The advice about increasing levothyroxine by 30% or by 25 - 50 mcg should be viewed in context, some ladies will start with e.g TSH 3.0, fT4 13.5 and others with TSH 0.5 fT4 19.5. The aim is to get TSH below 2.5 which usually means an fT4 in the upper half of its reference interval. So, sometimes there will be a need for a 50 mcg increase and in other cases (not very often) no increase will be needed.
I was told that it depends on the lab whether it's max 2/2.5 for TSH but overall the recommendation I've had and read is to increase by 50mcg per day for pregnancy and retest after 6 weeks. This is what I've done in both pregnancies- whether that's correct or not I can't say. You should also be referred to an endocrinologist if you're not already under one.
Congratulations! I went through a very similar experience with my first. What really helped us have a very healthy son was not my thyroid, It was what I read here progesterone.com/progestero... Hope this helps you too!
I can't add anything advice wise but I just wanted to say congratulations. What a very special and precious time for you. Onwards and upwards for 2022. Blessings x
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