TSH in pregnancy

[Nikki156]

Hello all, hoping someone can help! I’m 10 weeks pregnant and have never had a thyroid problem before. Around 5 weeks ago I found out my TSH was slightly elevated (2.9) - this is OK for normal life but above where they like it to be in early pregnancy (below 2). My T4 and T3 were both normal but I was put on 50mcg of Levothyroxine to try to bring the TSH down slightly. However, I have just had the results of a repeat blood test and my TSH is now 0.1. T3 and T4 are both still normal (T3 is 6 and T4 17.something I think he said). I am going to reduce my dose but seem to have swapped one issue for another and am now worried about what this could mean for the pregnancy. Can anyone offer any advice? Thanks in advance

[Den1987UK]

Hello Nikki156 I don’t know much as a guy about hypothyroidism and pregnancy but I would say to make sure your vitamins levels are optimal and very good. Also that making your diet optimal is very good will help also . TSH is low but at least you’re FT4 and FT3 are very good but depending on acual results could be better but I would not drop the levothyroxine dose at all or too low . if you can get the full results that would help . . Also getting a blood test for vitamin B12 D3 Folate and Ferritin would be good if you have not already . Also congratulations by the way.

[greygoose]

Low TSH is not an issue. It's low because the pituitary (TSH is not a thyroid hormone) has recognised that there's enough thyroid hormone in the blood and has reduced its output of TSH. You seem to have a good level of FT3 -although you haven't given the range so hard to say - so I wouldn't worry about it, if I were you. If you feel well, don't reduce your dose.

The TSH itself has no direct effect on the baby, or anything much else. It's two jobs are to stimulate the thyroid to produce more hormone - which is why it's high when you're hypo - and to stimulate conversion. You don't need either of those functions at the moment, by the look of it.

[Zebra5 in reply to greygoose]

Hi Nikki156 I apologise for coming onto your thread but something caught my eye that greygoose mentioned in her reply to you and I wanted to ask her more about it (not related to your pregnancy query though). It's about TSH's role in conversion. Greygoose mentions: "Its (TSH's) two jobs are to stimulate the thyroid to produce more hormone - which is why it's high when you're hypo - and to stimulate conversion." Please could you tell me more about this? What if your TSH is low or suppressed when you are on T4 - does that have an impact on the efficiency/rate of conversion? Many thanks!

[greygoose in reply to Zebra5]

It certainly can have an affect, but doesn't always, judging by what I've seen on here. But, going by the results you've just posted, conversion is not your problem, and your TSH is not suppressed.

[Zebra5 in reply to greygoose]

Hi greygoose - it was me, Zebra5, that asked the question about TSH's role in conversion, not Nikki156. Thanks for your response and sorry for the confusion. My TSH is suppressed and I do not convert as well as I would like to - which is why I was asking the question. Could you tell me more? Many thanks.

[greygoose in reply to Zebra5]

Hmm… I must be halucinating! lol

Well, there's not much else I can tell you, really. There's not much you can do about your TSH level. The only way to raise it is to reduce your levo, or whatever, and that is rarely a good idea. Besides, there are so many reasons why people are poor converters that it might not be due to the low TSH. I've seen some people on here with low TSH that convert perfectly well. It's not always possible to work out why you don't convert well. Sub-optimal nutrients can be one reason, so it's always a good idea to get those checked.

[Zebra5 in reply to greygoose]

Brilliant! Thank you very much!

[greygoose in reply to Zebra5]

You're welcome.

[diogenes Remembering]

This is OK in the first trimester, but if it continues ie TSH level in the second and later there is some cause for concern. I would ask for continual monitoring to be sure that all proceeds well. From what you say the FT4/3 is fine now. But do not let them write you off as a normal - it may or may not be true but any problem will show itself later on.

[Nikki156]

Thanks all, that’s really helpful. I’ve found something on ThyroidUK’s website which says T4 should be 10-18 in the first trimester and 9-16 in the second. T3 should be 3.4-6.6 in the first and 3.2-6.2 in the second. So, as I’m going into my second trimester, I’m thinking my TSH is too low and my T3 and T4 are at the upper end of where they should be. Forgive my ignorance here, but does anyone know the correlation between TSH and T3/4? I.e. If I reduce my Levothyroxine dose to 25mcg and get my TSH up a bit, should that bring down my T3 and 4 slightly too? Or does it not work like that?!

[SilverAvocado in reply to Nikki156]

Nikki156, Most of us would prefer to be at the upper ends of the ranges. Personally I think the numbers you quote from the website tend a bit low, most people will feel well with freeT3 in the top third or so of the range. It's okay to go all the way to the top of the range if necessary to resolve symptoms.

I would not recommend going all the way down to 25mcg of Levothyroxine, as at levels below about 50mcg you will start getting the problem that very low doses of Levo often cause more harm than good. They are enough to disrupt your body's own thyroid hormone regulation, but not enough to supplement it. Some people have those problems on 50mcg, too, so keep an eye out for symptoms feeling worse after a few weeks.

In general doctors tend towards too low doses, so it's quite unlikely you will end up overdosed, and much more likely to be under dosed. Doctors can often be quite negligent about monitoring thyroid health during pregnancy so it is really good yours has been spotted, and also really good that you're here doing your own research. Its important to double check everything doctors tell you about your thyoid and dose.

During and after pregnancy is a common time to develop thyroid illness. Sometimes it will return to normal when the pregnancy is over, or sometimes it lasts forever.

[SlowDragon Administrator]

Welcome to the forum

Congratulations on your pregnancy

Do you know if you have had thyroid antibodies tested? Most hypothyroidism is due to autoimmune thyroid disease also called Hashimoto's diagnosed by high thyroid antibodies

Also has GP tested vitamin D, folate, B12 and ferritin.

[Jasma]

Hi Nikki. Please don't worry about TSH, it's FT3 and FT4 that matter and it's not only fine but good to have these in the upper end of the ranges. Dana Trentini, aka Hypothyroid Mom has a good website with information you might find useful as well as a book about hypothyroidism and pregnancy. If you're feeling well you sound good. Good luck with the rest of your pregnancy and enjoy it.

[humanbean]

Having low levels of nutrients is a possible effect of non-optimal thyroid hormone levels, and is (obviously) undesirable in pregnancy.

It would be a good idea for you to ask for folate, vitamin B12, vitamin D, iron and ferritin levels to be measured, if these are not done automatically. If you can't get them all done then you can pay for private testing with finger-prick testing. Tests have to be ordered online and it isn't necessary to see a doctor.

[humanbean]

Some links you might find of use or interest :

patient.info/doctor/thyroid...

apps.nhslothian.scot/refhel...

academic.oup.com/jcem/artic...

[Nikki156]

Thanks all! So glad I found you. I have a couple of further Qs if that’s ok - my GP has suggested either going down to 25mg and 50mg on alternate days or just reducing straight to 25mg. I’m inclined to the first option after seeing your comments. Is it normal to take different doses on alternate days? Also I now have some 25mg tablets but they seem to be different to my others (made by Mercury Pharma instead of Teva). I’m assuming it’s basically the same thing? Don’t really want to alternate brands as well as doses so I might take 2 x the 25mg one day then 1 the next.

[humanbean in reply to Nikki156]

People can and do take different doses on different days. I must admit though your results don't seem to justify a reduction.

If you really, really want to lower your dose, perhaps you could reduce it on just a couple of days a week, say Monday and Thursday rather than on two consecutive days.

[Nikki156 in reply to humanbean]

Thanks humanbean. Interesting - I wonder if I should forget the GP and go see an endocrinologist. The GP seems concerned my TSH is so low.

I was wrong about my T3 above if that makes any difference? Have the written results now and it is actually 4.5. Then T4 is 17.

[humanbean in reply to Nikki156]

I wouldn't reduce with a T3 of 4.5.

[humanbean in reply to Nikki156]

If you have your results adding the reference ranges would be useful e.g.

Free T4 17.x Range (12 - 22)

Free T3 4.5 Range (3.1 - 6.8)

or whatever the ranges are for your results - different labs have different ranges.

[Nikki156 in reply to humanbean]

Ahhh. Is 4.5 low then?

The results are:

TSH 0.1 mU/L (0.27-4.20)

Free T4 17.0 pmol/L (12.0-22.0)

Free T3 4.5 pmol/L (3.1-6.8)

My results prior to going on the Levothyroxine were TSH 2.91, T4 14.9 and T3 5.6. So all fine but they were concerned about the TSH being on the high side for pregnancy. I’m now pretty confused!

[humanbean in reply to Nikki156]

There is another way of looking at results and reference ranges that can sometimes "feel" more informative - use percentages through the range.

Free T4 17.0 pmol/L (12.0-22.0) Your result is 50% of the way through the range

Free T3 4.5 pmol/L (3.1-6.8) Your result is 38% of the way through the range

Most people with under-performing thyroids feel better with a Free T4 around 60% - 70% of the way through the range and a Free T3 around 50% - 60% of the way through the range.

(Different people quote different percentages as being optimal but there is general agreement that most people feel better with thyroid hormone levels in the upper half of the range, but not too high in range.)

If you were to reduce your Levo dosage it might make your TSH rise a little bit. But it will probably lower your Free T4 and may affect your Free T3. TSH is a pituitary hormone, and I've never heard of it being of direct importance to a foetus. (I'm not a doctor so I could be wrong on that.)

But your Free T4 and Free T3, which are both produced by your thyroid, are both extremely important to a foetus before they've grown their own thyroid and it has started working. Since your Free T4 and Free T3 couldn't be considered even slightly high as they are at the moment, they don't constitute a danger to you or your offspring.

(I'm assuming you already know that as a general rule the higher your TSH the lower your thyroid hormone levels are. And the lower your TSH the higher your thyroid hormone levels are.)

Doctors have been taught that TSH is king and the actual levels of thyroid hormones are unimportant because TSH production is assumed to be perfect. The assumption is that the pituitary (and the hypothalamus, which produces a hormone the pituitary pays attention to) works perfectly in everybody. This is clearly nonsense.

Another thing that doctors get wrong is that they often assume the thyroid produces T3 by conversion from T4, they don't believe that the thyroid produces T3 directly at all. (I only read this very recently and it was news to me, so take it with a pinch of salt.)

Other organs in the body which DO produce T3 by conversion from T4 are the liver, the gut, the skin and some others. And doctors assume that conversion also works perfectly in everyone. This is so incredibly unlikely that many of us on this forum just ignore TSH unless it is high and indicates the person is hypothyroid and under-medicated. We prefer to go by the actual real thyroid hormone levels - the Free T4 and Free T3.

Whatever you decide to do, I just want to wish you good luck for a healthy pregnancy and a trouble-free birth.

Oh - another thing... You might like to see a graph of what TSH looks like in people with healthy thyroids. It makes your result of 0.1 look more normal than your doctor might suggest it is :

healthunlocked.com/thyroidu...