Is TSH biologically inactive on non-thyroid cells? Pregnant, urgently need correct information.

[kimberlyR]

I am 6 weeks pregnant, TSH 30 (0-4), FT4 0.8 (0.9-1.7). I was flagged as high risk pregnancy with TSH 30 and sent to fetal-maternal medicine doctor for consultation. The gentleman is older and I am not convinced he is well read on new thyroid research. He basically said everything is totally fine, that my FT4 was barely low and TSH doesn't matter for baby? TSH is inert (inactive) on non-thyroid cells and only a signaling molecule for thyroid and the only number that matters is FT4? That TSH is a 'screening test' for hypo and once a person has hypo only FT4 is relevant? He claims that my pregnancy is totally fine and my increased dose will resolve the numbers. What I am reading online so far (fetal development issues with high TSH) contradicts his statements. Any thoughts much appreciated. I figure if he is correct, why is everyone on this site still discussing TSH if the only number that matters for hypo patients is FT4?

[diogenes Remembering]

Your doctor is misinformed almost beyond belief. TSH is the marker for underactive thyroids. In early pregnancy the foetus isn't making thyroid hormone eg T4 and is getting it from you. At your stage of pregnancy, the normal non pregnant FT4 range applies. Later on, the increase in oestrogen opens up your cells so that you don't need as much FT4 in your blood for adequate amounts to get in. Therefore FT4 below the normal range combined with a TSH as high as this requires urgent treatment early in pregnancy. So long as the TSH value is accurate, then you are very hypothyroid and need T4 therapy right away for both your sake and the baby.

[Kitti1]

I'm not expert particularly when it concerns hypo and pregnant but if I were you I demand a second opinion ASAP. With your TSH so high and t4 out of range your woefully under medicated. What dose were you on and have they put your dose up since those blood test ?

From the bits I have read regarding hypo & pregnancy I thought you need your T4 at the top of the range and TSH surpressed. I hope someone more knowledgeable comes along soon. And you get the right medical treatment soon too.

[Clutter]

KimberlyR,

I'd get shot of that doctor PDQ because he doesn't know what TSH and FT4 should be during pregnancy. Having TSH >3 increases the risks of miscarriage and post partum psychosis and FT4 is below the lab ref range which is not good for foetal development. Has your Levothyroxine dose been increased since your pregnancy is confirmed and TSH 30?

The British Thyroid Association recommend:

13. The serum TSH reference range in pregnancy is 0·4–2·5 mU/l in the first trimester and 0·4–3·0 mU/l in the second and third trimesters or should be based on the trimester-specific reference range for the population if available. These reference ranges should be achieved where possible with appropriate doses of L-T4 preconception and most importantly in the first trimester (1/++0). L-T4/L-T3 combination therapy is not recommended in pregnancy (1/+00).

onlinelibrary.wiley.com/doi...

You may want to read the 2017 Guidelines of the American Thyroid Association

for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum which also recommends trimester-specific reference range for the population should be achieved.

online.liebertpub.com/doi/p...

[kimberlyR in reply to Clutter]

Thank you immeasurably for this information. I wanted to believe the fetal maternal doctor but it seems too good to be true. And in his description of thyroid hormones he mixed up T4 and T3 so I was skeptical of his in depth understanding. I will read the 2017 guidelines. My dose was increased one week ago upon the TSH 30 result. Previous dose was 75 mcg NDT and current dose is 100 levo, but I do not feel well on levo (history of right-sided neuropathy that relsolved on NDT). I'm already having some nerve pain after a few days on levo but I suppose that could be from the stress of this situation.

[Clutter in reply to kimberlyR]

KimberlyR,

I'm sorry to be negative about this but I don't think a 25mcg dose is sufficient with your TSH so high. It is usual to increase Levothyroxine dose by 25-50mcg when pregnancy is confirmed and TSH is in range. I think you need to increase further.

The ATA document is very long. You may want to use the Ctrl+F function to find "trimester-specific reference range" info.

[Saggyuk]

Hi Kimberley

He is absolutely totally incorrect and you must see someone else asap as he doesn't sound that knowledgable. Your tsh is very high - this goes high when your body doesn't have enough thyroid and the higher it goes, the less it is getting. Your T4 is low also and needs to be much higher. This means your thyroid is struggling to produce what it is producing which is far far too low especially for pregnancy and this is very likely to get worse during the pregnancy. My endo increased my T4 by 50mcg just at the mention of pregnancy and my results remained stable on this throughout. What dose are you on at the mo and how much did he increase it by?

Ah sorry about the edit, just realised you're on meds and they increased - had thought you were completely unmedicated. However, you really need to be referred to endocrinologist and you need to retest on the higher dose and have additional monitoring by the endo throughout your pregnancy. You should really be referred to an endo anyway.

[Saggyuk in reply to Saggyuk]

I had additional more regular scans and monthly blood tests if that helps and the endo was adamant on keeping my tsh at 1 or below

[kimberlyR in reply to Saggyuk]

Thank you for your response. I was on 75 mcg NDT. They now have switched me to levo 100 mcg. I never felt well on levo before but I have one child and that was my brand / dose 4 years ago when I was pregnant with her so they insisted on that brand and dose for now.

[Saggyuk in reply to kimberlyR]

Yes, but unfortunately, most people require more and more as the years go by until fully replaced so what you had four years ago will likely not apply now. They really really shouldn't have quickly changed your meds from one to the other like that while you are pregnant either as this could have caused issues in itself as would have been quite a shock to the system. An endo will also check your T3 levels which might be a bit off coming off the ndt.

Try and get a referral to endo in the next few weeks as advised by NICE - guidelines they have to follow - it states categorically that any pregnant female should be referred to endocrinology specialist. You should get follow up tests soon as you are likely to need another increase of 25mcg.

See link below

cks.nice.org.uk/hypothyroid...

Show this to your GP. It also states that any changes to meds upon confirmation of pregnancy should have been discussed urgently with an endocrinologist and not decided upon themselves!!!

[SilverAvocado in reply to kimberlyR]

KimberleyR, I just noticed you have changed over from being on NDT to being on Levothyroxine. If this is true you haven't had a straightforward increase of 25mcg, but a switch to a totally different medication, which is not so straightforward.

NDT is usually measured in Milligrams, and Levothyroxine in Micrograms. They mean completely different things, the NDT contains T4 and T3 and these are measured in Micrograms just like the synthetics.

I'm more familiar with measuring NDT in grains, but I think 75mg is a bit over 1 grain, maybe 1 and a quarter?

1 grain is equivalent to about 73mcg of Levo. So the quarter would be 18.25, for a total of 91.25mcg.

But this comparison is not at all exact, it's something that needs to be worked out by trial and error. This comparison assumes the T3 in the NDT is 4x as potent as T4, but some people say it's only 3x as potent, and others say as much 10x.

And none of those comparisons really work, because it depends how good your body is at utilising these hormones. If you struggle to use T4 only it doesn't matter what the comparison is. Personally I have been much better on NDT, far better than synthetics including T3.

But it's also important that you may not have had a meaningful increase at all, and it can be shaky changing from NDT to Levothyroxine. Ideally you need a doctor that knows what they're doing, but you definitely need a proper increase.