High tsh but high T4. Low B12: Good Evening... - Thyroid UK

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High tsh but high T4. Low B12

pipshaw profile image

Good Evening.

Advice Please :). Had blood results today, my tsh has gone down from 10 to 7.5 since last results but T4 remains high at 11.5 (slightly above range). Doc has reduced levo to 25mcg daily from 50 as it appears thyroid is producing t4. This has confused him so has forwarded me to an Endo and said they may have to do something to my Thyroid, what would this mean? My B12 is also low at 158, he has prescribed 5 x B12 injections over 5 weeks, does this sound right? He did prescribe B12 tablet after my previous blood test but the reading of 158 was unchanged. I also have Hashimotos.

I'm Male age 55. Thanks in advance for any advice.


16 Replies

Hi Phil

What’s the laboratory reference range for that T4 result?

At first glance, it’s looking like your doctor might be a complete numpty when it comes to treating thyroid disorders but that rather depends on the answer to my question about the range.

Re the B12 - that sounds more promising (because that’s a very low result and it will be making you feel awful) but he really ought to be doing more tests first to see if you test positive for pernicious anaemia. Plus “over 5 weeks” isn’t in fact the correct protocol for treating Vit B12 deficiency.... :(

pipshaw profile image
pipshaw in reply to Jazzw

Hi Jazz,

T4 range is 4.6>10.5. I also thought it strange about the B12 routine, Maybe this is why he has referred me to an Endo not sure, what would be the usual protocol regards B12 injection. I've recently moved to Spain by the way so not sure if they do things differently here. Thanks for reply

Well, let's face it, it doesn't take much to confuse a GP. If only they would test the FT3, that would probably solve a lot of these so-called mysteries. I would imagine, for your TSH to still be that high, you're not converting that levo to T3, and your FT3 is low. Reducing the levo is also going to reduce the FT3 as well, and make you feel worse. But GPs know nothing about conversion.

Totally agree with Jazzw about the B12.

SlowDragon profile image

Previous post


Have you also had folate, vitamin D and ferritin tested yet?

These are likely low too

pipshaw profile image
pipshaw in reply to SlowDragon

Hi yes I had those done this week also and they are within range. Thanks

SlowDragon profile image
SlowDragonAdministrator in reply to pipshaw

Can you add your actual results and ranges

Within range may not be optimal

pipshaw profile image
pipshaw in reply to SlowDragon

Hi Slowdragon

Ferritin is 168.7 Range 30>300

Folic Acid 6.87 Range >4.0

Vit D 41 Range 30>100

B12 158 Range 206>678

Thanks for reply

SlowDragon profile image
SlowDragonAdministrator in reply to pipshaw

So your B12 and folate are both very low. What's GP doing?

You should have had full testing for Pernicious Anaemia before starting on loading B12 injections

folic acid supplements should not be started until 48 hours after first B12 injection

Post these results on PAS healthunlocked for specific advice. They are the PA experts. Or Gambit62 may add some advice too


You need FT3 tested along side TSH and FT4. Looks like you may not be good converter. Or low B12 is currently affecting results

Private tests are available, if you are back in UK any soon

No idea about testing options in Spain

Thousands on here forced to do this as NHS often refuses to test FT3


Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.

All thyroid tests should ideally be done as early as possible in morning and fasting. When on Levothyroxine, take last dose 24 hours prior to test, and take next dose straight after test. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, GP will be unaware)

As you have Hashimoto's are you on strictly gluten free diet? Many find it helps, sometimes significantly

Ideally ask GP for coeliac blood test first







SlowDragon profile image
SlowDragonAdministrator in reply to pipshaw

Forgot to say

Vitamin D and ferritin are fine

Your high FT4 (or is it total T4?) could be due to transient Hashimoto's flare. This is when you get temporary high levels as thyroid dumps load of hormones

pipshaw profile image
pipshaw in reply to SlowDragon

It just says ‘T4 in serum’ on the results not sure if it’s ft4 or total t4 it’s measured in mcg/dl if that helps. As I say I’m living in Spain so I expected vit D to be ok but I’ve just had appointment come through to see Endo next week which will hopefully shed some light on what’s going on

pipshaw profile image
pipshaw in reply to SlowDragon

Also gp didn’t mention anything about Folic Acid being low so I’m not supplementing at the moment

Gambit62 profile image
Gambit62 in reply to pipshaw

suggest posting on the pasoc forum - if the results were private then GP may want to run their own results but it is very unlikely that you aren't deficient with a result that low. If you have previous results showing levels in past have been significantly higher then that would be good evidence of an absorption problem.

Lot more on the pasoc forum


pipshaw profile image
pipshaw in reply to Gambit62

Hi Gambit do u mean are deficient or aren’t deficient and on which result? Thanks

Gambit62 profile image
Gambit62 in reply to pipshaw

unlikely that you aren't = almost certain that you are

You might find this old thread interesting. Not suggesting that anything in it is what’s happening to you, but your doctor should be investigating further rather than guessing what to do.


Hi all so what would be a usual B12 protocol for this. I’m reading conflicting reports after googling?

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