Odd blood test results - TSH normal, FT4 high. - Thyroid UK

Thyroid UK

144,294 members169,732 posts

Odd blood test results - TSH normal, FT4 high.

Bananagal profile image
6 Replies

Hi all.

Hoping for some insights on a recent set of medichecks bloods I had done. I was primarily testing for vitamin and mineral levels as I am breastfeeding at the moment, and being lactose intolerant I worry about getting enough calcium and Vitamin D (incidentally all fine bar slightly low Vit D levels). However, I also got TSH and FT4 tested as there is a strong family history of hypothyroidism (both grandmothers and my Mum) and I do suffer from fatigue and low energy (probably no surprise with 2 kids).

These were the results:

TSH 1.26 (range 0.27 - 4.2)

FT4 25.6 (range 12 - 22)

A year ago I had the same test with the same ranges, and my results were normal (TSH 1.05, FT4 20.21). Antibodies and FT3 all normal too (I didn't test those this time.)

Clearly these suggest that I may be developing hyperthyroidism if anything, but I can't find any info anywhere on what it means when your TSH is normal and FT4 high? I don't really have any symptoms bar the tiredness and being a bit warmer than usual - but I had that last time I breastfed too. Shouldn't I be anxious, slim (ha!) and full of nervous energy?!

Any ideas? My GP just said, "your TSH is normal, you're fine. I wouldn't worry unless you start feeling ill." She's probably right, but I'm curious - any ideas what could have caused this odd result? I may check again in 6 weeks or so just for peace of mind.

Thanks!

Written by
Bananagal profile image
Bananagal
To view profiles and participate in discussions please or .
Read more about...
6 Replies
greygoose profile image
greygoose

You really should have retested your FT3. That completes the picture. Your TSH is actually a long way from developing hyperthyroidism. But you can't really know anything for certain without the FT3, I'm afraid.

Bananagal profile image
Bananagal in reply togreygoose

Yes, I will get a full set again next time I think. Unfortunately the package I chose this time only included FT4 and TSH. Hopefully FT3 will offer some more insight...

greygoose profile image
greygoose in reply toBananagal

I'm sure it will. :)

jimh111 profile image
jimh111

It could suggest mildly impaired deiodinase due to e.g. selenium deficiency, this would be accompanied by a low fT3.

However, your thyroid hormones are most likely normal. These are 95% reference intervals. i.e. 95% of the healthy population with have TSH or fT4 or whatever, that falls within the intervals. So, 5% of healthy people will have a result that is outside of the interval. The most likely reason is that your fT4 just happened to be a little above the upper limit of its reference interval, you were one of the 5% on this occasion.

Hi, are you taking Biotin (vitamin b7)? Or a multivitamin with it in? If yes this can skew your results and you could stop taking it a week or so before the test. 🙂 but a full picture would only be had with having your t3 tested. Good luck with everything x

Bananagal profile image
Bananagal in reply to

Thanks - yes, I take a breastfeeding multivitamin with 150 ug of biotin in it. That may explain it, thanks!

Not what you're looking for?

You may also like...

Hashimoto's; Suddenly high TSH AND high FT4?

Hi all, it's been a while since I've been here. I've got Hashimoto disease and I've been treated...
Flower3 profile image

Low TSH Blood Test Results following changing to Armour Thyroid

Hi Guys, I was taking 100mcg levothyroxine until 20th January 2017. I managed to convince my...
Jose88 profile image

Is there Relationship between TSH, FT3, and FT4? How could I Improve my FT4 and FT3 levels?

I would appreciated member's comments on the following questions: (1) is there an accepted optimum...
Adam10 profile image

TSH, FT4 & FT3 normal! (?)

I had my first blood test 2 months ago, where my TSH was on the high side, but my FT4 and FT3 were...

Help with Blood Test Results

Good Morning, I have just been back to my endocrinologist as, after feeling really good for the...
Timmersby profile image

Moderation team

See all
PurpleNails profile image
PurpleNailsAdministrator
SlowDragon profile image
SlowDragonAdministrator
GlowCoach profile image
GlowCoachAdministrator

Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.

Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.