Pregnant and need thyroid tested again - Thyroid UK

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Pregnant and need thyroid tested again

Ariemai6 profile image

Hey everyone, I’ve recently found out I’m pregnant :). So I’m getting my bloods taken at the GP’s once more, I have two problems however. The only possible appointment I can go to is late in the afternoon after work which means no fasting from food and levothyroxine before blood draw. Is there anything I can do to improve the accuracy of the test?

As well as this I have been taking an extra 25 mcg of levothyroxine since I found out as advised by the British Thyroid Organisation. This was before I spoke to the GP who said they do not wish to increase from my usual dose of 100 mcg until they have these results back, should I stop taking the extra 25 mcg until I get my bloods retested to give a more accurate result? (and therefore get an actual prescription for 25 mcg, as right now I’m using a pill cutter on my leftover 50 mcg tablets,....not ideal).

Fortunately I quickly sent my fasting bloods to medichecks to see what the real picture is as I know from previous occasions that fasting bloods really do differ from non fasting. I’m prepared at this stage to monitor my own bloods privately as my GP is more than a little confused. After asking about my thyroid problem I had to explain that I had Hashimoto’s and how I had found out which prompted the GP to ask when I last had it.....I then had to explain Hashi’s is an autoimmune condition. They looked a little perplexed...That was a bit awkward 🤔😆.

10 Replies
SeasideSusie profile image


As TSH below 2.5 is crucial to a successful pregnancy in the early stages (not sure of level later on) and as TSH is highest in the morning and lowest in the afternoon then you really should arrange your blood tests early morning. Why can't you go before work or arrange with your employer for you to attend a GP appointment for the appropriate time?

If a prescription for 25mcg Levo means a different brand, then I would avoid that at all costs and stick to cutting your 50mcg tablets.

shaws profile image

I agree with SeasideSusie an early a.m. appointment is vital. TSH is highest early a.m. and drops throughout the day. So even fasting all day wont make much of a difference as your TSH will be lower p.m.

Phone up to see if there are any calcellations early a.m.

Hey ya seasidesusie, unfortunately I’m just about to start a new job (within the same organisation) that is Monday to Friday and starts at 07:30 in the morning. Haven’t disclosed to my manager that I’m pregnant as I haven’t even met her yet. I used to do 13 hours shifts which meant I had whole days off during the week, handier for early morning appointments but very hard physically over time.

Ariemai6 profile image
Ariemai6 in reply to Ariemai6

I feel it’s far too soon to ask my manager to come in a little late so that I can make a morning appointment, so I really am in a pickle 😟

SlowDragon profile image
SlowDragonAdministrator in reply to Ariemai6

Can GP surgery offer a Saturday morning appointment, or the local hospital perhaps

Ariemai6 profile image
Ariemai6 in reply to SlowDragon

Unfortunately the GP surgery doesn't open on Saturdays, not sure of the hospital being an option, however this might be available to me once I start being seen by a midwife perhaps. The GP has also referred me to an endocrinologist so that might give me more options hopefully, but only as the pregnancy goes on.

In comparison to Free T4 and Free T3, TSH changes relatively slowly. If you change your dose and then test your TSH a few days later it probably won't have settled down completely and won't tell you anything you can rely on.

If you're taking a higher dose of Levo than your doctor is aware of, and you are going to be tested in the afternoon, then your TSH could be a lot lower than your GP likes. I think there might even be a risk of you getting your dose reduced.

I don't know a way of quickly over-riding the circadian rhythm that is one of the factors affecting your TSH. If such a method had been discovered we'd all be doing it before testing.

This may be of some help - see the graphs on page 2. Note that "TSH" and "Thyrotropin" are two names for the same thing :

But you should decide for yourself if your doctor will be convinced by it. It might be wise to buy your own levothyroxine so you can treat yourself at a level suitable for you, but I don't know of any reliable sources of levothyroxine. You could write a new post and ask.

Once you have your Medichecks results it would be worth posting a new post and asking for feedback.

humanbean profile image
humanbean in reply to humanbean

This might help - print it out and take it with you to the doctor's appointment :

This is the link to the full paper :

Ariemai6 profile image
Ariemai6 in reply to humanbean

Thanks Human bean for that information. Its a tricky one because I want to be upfront with my GP but unfortunately I don't trust their judgement on correct dosage and so it leaves me to go it alone somewhat and that is also frightening. What I could do is provide my medichecks results to the GP and hope they accept them and be honest that I am now taking the extra 25 mcg in the hopes that they will review their own tests with that in mind.

I'm 5 1/2 weeks, so still very early days. I last had thyroid tests done at the GP practice in late June but I foolishly forgot to fast and leave off levothyroxine and my T4 was sitting high at 24 (range 12-22), TSH 0.62 (0.27-4.2). In a complete turnaround to their usual doctrine and to my great relief my GP agreed to keep me at the same dosage despite being slightly raised.

Because I wanted a true indication of my thyroid status I then performed a fasting medichecks test a few days later and T4 was 20.9 (12-22), T3 4.09 (3.10-6.80) and TSH 0.76 (0.27-4.2). My TSH in these results was sitting lower than it ever had before so perhaps my dosage was as optimal as it was ever gonna get on levothyroxine only treatment.

humanbean profile image
humanbean in reply to Ariemai6

I hope it all goes well for you, and good luck with your doctor.

Having the correct levels of thyroid hormone is actually more important in the first trimester because it takes a while for a foetus to grow a functioning thyroid. Once they have grown a thyroid they are less reliant on the mother's thyroid hormone levels.

It is also important to have good levels of nutrients during pregnancy. Do a search for "low iron in pregnancy", "low vitamin D in pregnancy", and the same for vitamin B12 and folate, plus any other common nutrients e.g. other B vitamins and zinc.

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