How long do I need to wait in between blood tes... - Thyroid UK

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How long do I need to wait in between blood tests after dose increase

hashihol profile image
11 Replies

Just had my Levo increased to 125mcg. Last test results on 16/11/21, TSH: 4.31, fT4:15.5. Trying to get pregnant and wondering how long I can wait to get my bloods re-tested. NHS say they won't test me for at least 6 weeks after dose increase and I want to know if it's worth me getting a medichecks test or trying to see a private endo in the mean time? I've only been on the increased dose for 2 days so far, so I know i can't be tested for a few weeks yet anyway, but does anyone know how long? It's pretty stressful trying to get my TSH levels in the right place in time for my next fertile window, but am working on reducing the stress too!

11 Replies
SlowDragon profile image

TSH is slow to respond to any dose change

6-8 weeks minimum before testing is general recommended time

Meanwhile you can be working on vitamin levels if necessary

When were vitamin D, folate, ferritin and B12 last tested

What are your most recent vitamin results and ranges

hashihol profile image
hashihol in reply to SlowDragon

The thyroid results shown here are from september as they wouldn't retest when I got my FBC tested as it was too soon after the last test. I don't believe I've had my vitamin D tested recently, however I spent all summer in the sun and have been taking 4000IU a day sublingually since october.

Bloods from october which is the last time I had my vitamin levels checked
SlowDragon profile image
SlowDragonAdministrator in reply to hashihol

Test vitamin D twice year when supplementing

NHS easy postal kit vitamin D test £29 via

It’s trial and error what dose we need, with hashimoto’s we frequently need higher dose than average

Vitamin D and thyroid disease

Stevie profile image

I wouldn’t try yet to get pregnant yet, your TSH isn’t good. I was under a professor, he said for a true result, it’s 3 mths Do check your vitamins so important Ferritin B12 folate

Get pregnacare and build yourself up while your waiting

The day you know your pregnant you take another 25mcg for the pregnancy & stop the day you give birth

My daughter has had 2 successful pregnancy & I’m from. Family of 10 all hypothyroid. Wishing good luck, I’m sure you’ll be fine

hashihol profile image
hashihol in reply to Stevie

Thanks for your message. My vitamin levels are good and I've been on all the supplements for over a year now. I will wait until my thyroid is stable. I read about the taking the extra 25 on result of a positive pregnancy test, but of course if I got pregnant now having only just increased my dose, I imagine that wouldn't be too clever of me! I'll wait til the blood results are fine and stable. I think I'm scared I'm getting too old, but you're right, rushing it isn't the way forward. Thanks for your help :)

tattybogle profile image

"Tested on 2nd July TSH was 15.09, then for some reason I was tested only a week later, 9th July, TSH was 11.4. I conceived on 23rd July (I know the exact date, hehe). On 12th August TSH was 10.5 and I increased the dose then from 75mcg to 100mcg but it was obviously too late 😔"

"Just had my Levo increased to 125mcg. Last test results on 16/11/21, TSH: 4.31, fT4:15.5"

" I've only been on the increased dose for 2 days so far, so I know i can't be tested for a few weeks yet anyway, but does anyone know how long? It's pretty stressful trying to get my TSH levels in the right place in time for my next fertile window"

I'm really concerned that you are rushing things for your next pregnancy.

It's not so much about 'getting the TSH into the right number before conceiving' ... it's more about getting 'your dose (and thus the TSH) to be stable at the right level before you conceive.'

To minimise the risk of miscarriage you want optimum AND stable thyroid hormone levels before you conceive.... and you are a few months away from achieving that.

You need to do 6 weeks (at least) on 125mcg .

then see what bloods say ... you may still need another increase / or not.

And given your previous experience , i'd strongly suggest you then wait (at least) another 6 weeks (even if TSH is under 2 and dose is kept at 125mcg) and then repeat bloods again to see if bloods really are stable on 125mcg or if dose needs adjusting again (if TSH has started to rise again.)

This is because 6 weeks is the earliest you can test blood to see how TSH has responded to a dose change... it may well change again on the same dose as the body slowly accommodates itself to all the changes the increase brings.

The fact that your TSH rose to 15 in july on 75mcg Levo is a sure sign that you are quite along way off being stable on a dose yet.

Pregnancy itself will induce a big swing in levels .. which is normal , but i think you want to be SURE that your own levels aren't still swinging around wildly before you try and support another pregnancy.

I'm sorry xx , i do realise this is all very upsetting to think about , but i think it needs saying.

hashihol profile image
hashihol in reply to tattybogle

Thanks so much for the kind reply. Judging by my ovulation tests I am due to ovulate tomorrow and having read your reply I've decided I will definitely wait now.

Thanks also for referring back to my previous post. It's all very long and complicated. I think the reason I'm rushing is because I'm a 'geriatric' when it comes to pregnancy and I'm scared I've left it too late. We'd been trying for a year, then I finally got pregnant and as you know it didn't work out.

Do you have any idea why my results seem to be swinging about so much in the last year? I started on only 25mcg in July 2018 and felt fine on that until January this year when I slowly but surely started needing the increased dosage, til I got to where I am now at 125mcg. It seems so strange because I really do keep an eye on all my vitamin levels (I am studying naturopathic nutrition so have learnt a lot about these things) and I'm the healthiest I've ever been, especially where my diet is concerned. I can't seem to find a reason for my thyroid to have suddenly got so much worse. I imagine there is no reason that we know of... maybe stress adding to things?

tattybogle profile image
tattybogle in reply to hashihol

Your immune system attacked a bit of your thyroid, but not too much of it ,, so you were ok on 25mcg for a while. (or perhaps they should really have increased you to a full dose at this point ? .... 25mcg isn't really much use to anyone, NHS guidelines tell then to start at 50mcg for a start)

Then it attacked a bit more (as evidenced by the antibodies going higher, showing another attack had happened and they came along to clean it up) meaning you needed to replace more T4 to compensate.

So your dose had to be increased,, and it seems it definitely needed to be increased to the full amount at this point , because despite an increase to 50mcg, your TSH still went up to 15 saying "we really need more T4/3 please"

So you clearly now need a full replacement dose , which is usually somewhere between 100-150mcg for most of us.

It's just what happens .

Autoimmune Thyroid Disease is a slow degenerative stop /start process, that no one really knows how to control.

We know that once we see raised TPOab in someone who has a slightly raised TSH, there is a big chance they will eventually end up needing to replace the full amount of hormone because the thyroid will eventually become so damaged it can't keep up.

This is why the NHS will give you Levo before you become 'totally' hypothyroid, once they see raised TPOab .. because they accept that this means you are probably going to end up there anyway at some point in the future .... it may take several years, or just a few months to get there , nobody can predict the speed , but that's where it's going once it starts.... a defunct thyroid gland.

You job now is to get settled on the correct full replacement dose, as efficiently as possible without rushing so fast you overshoot the goalposts.

And THEN get pregnant :)

hashihol profile image
hashihol in reply to tattybogle

Thank you so much for this. It does feel good to know that someone knows and cares about what's going on. My friends are sick of hearing about all this. Thanks for laying it all out for me and I hope you are somewhere that's ok/acceptable in your own thyroid journey!😊

tattybogle profile image
tattybogle in reply to hashihol

Thankyou. yes i'm ok. Being able to talk to people dealing with the same thyroid issues is a real improvement on how i felt before i found my way here.

And it's a nice feeling to be able to share what i've learned to help people understand how it actually works,

People who haven't had to deal with it (including GP's) think it's such a simple thing that's so quick to fix, which makes it very hard to talk to anyone about it without coming across as an obsessive hypochondriac.

Try and trust your body to know what it's doing here ... when your thyroid levels are good enough and its monitoring system senses that levels are stable enough.. then it will enable you to get pregnant and carry a baby to you.


Greeneyes14 profile image

Hi, I have been on 125mcg for 4 weeks after a persistent high TSH. GPs wouldn't touch me for 8 weeks for bloods, so I did a private test after 4 weeks on this dose (6 weeks since my last NHS blood test), and like you, I'm trying to get it in range before TTC. Finally, my TSH has dropped to below the target 2.5! I'm having another blood test before my expected ovulation window so 🤞 my TSH remains where it needs to be.

If I was you I would do another medicheck after 4 weeks, it will be worth it. Goodluck!

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