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Thyroid UK
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Optimal TSH and T4 levels?

What are considered optimal TSH and T4 results in the UK for someone with Hashimoto's diagnosed based on family history, raised antibodies but normal levels for everything else, and symptoms of anxiety, depression, poor concentration and memory?

Despite a trial of 25mcg of thyroxine I still feel terrible. I know this is too low from previous posts and responses but the GP has recently upped my antidepressant and said to wait before upping thyroxine as otherwise it would be hard to know what helped. I agree with this.

In two weeks I am due back at the endo and if I am not feeling better I want to push for a higher dose of thyroxine or NDT. It will have been 4 weeks since increasing the antidepressant so I'll know if that has helped or not.

13 Replies

Halinka, Generally, thyroid levels are optimal with TSH around 1.0, FT4 in the upper range and FT3 in, or towards, the top third of range. I think your GP could have tried upping the thyroxine to see whether you feel better before upping the ADs.


Thanks Clutter. Had to have a routine blood test last week (not for thyroid) but I noticed they tested TSH and Ft4. TSH was 1.48 and T4 was 14. Ferritin was borderline. Folate fine. B12 also at 500.


Halinka, there scope for a dose increase to 37.50 to 50mcg depending how low a TSH your GP is prepared sanction. FT4 14 is on the low side, a dose increase will improve it.

B12 500 is unlikely to be deficient but it may improve energy and mood if you supplement to boost it higher. PA Soc say 1,000 is optimal.

Ferritin is borderline for what? Optimal is half way through range.


Ferritin range was 20-300 and I was 25.


Halinka, that's borderline deficient. You need to supplement Ferrous Fumarate 210mg and take each tablet with 500-1,000mg vitamin C to aid absorption and minimise constipation. You need it between 100-150 which will take a while. Retest in 6 months and take iron 4 hours away from Levothyroxine.


Hi, I was taking ferrous fumerate but found it too constipating even with vitamin C so I now take 'Floradix' on the advice of the health food shop owner locally to me. His opinion on the prescription stuff is that you may as well take iron filings! Suffice to say, I have been on the floradix for three weeks and my iron levels are back to a healthy level. Am still terribly tired but at least am not anaemic now!



There is so little elemental iron in Floradix that it will take years for most people to improve their iron levels.

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Thanks Clutter. Does low ferritin effect the thyroid in any way?


Halinka, yes, good levels aid absorption of thyroid replacement and conversion, while low levels can make it difficult to tolerate dose increases without feeling hyper. Low levels cause fatigue and may cause hair loss too.


Once again thank you Clutter. Is it easy to explain why low ferritin levels lead to feelings of being hyper on dose increases? Also, what does hyper feel like?

My GP will be fine with a dose increase as long as my endo sanctions it.

I'm startled at how little GPs know about thyroid disease. My dad who has Hashimoto's and is on 100mcg thyroxine just had results back from the GP. Apparently they were fine even though his TSH is 0.2 and he had taken his thyroxine before hand. I think that is too low no? T4 was 14. Of course they don't even check T3.


A TSH of 0.2 is not a problem so long as FT4 and FT3 are in range. If he took his thyroxine before the test then the 'real' TSH reading would have been much higher. You don't state the range for the T4 reading but normally t4=14 is below half way, not in the top quartile where it should be.


Halinka, If you were feeling hyper you could be feeling 'wired and tired', agitated, restless, have a racing pulse and heart rate, feel hot, maybe sweaty, might have diarrhoea.



GPs are generalists, not specialists. They have a broad, but not in depth, knowledge of most conditions and refer to specialists when greater knowledge and expertise is required. Some GPs understanding of thyroid does seem to be minimal.

Why do you think your father's TSH is too low? If FT4 14 is within range he isn't overmedicated.


Hi Clutter, I can't recall which thread it was on but I read it somewhere on here. Thanks, Halinka


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