Thyroid UK
87,516 members102,230 posts

What does it mean when TSH and T3 are OK but T4 is high?

Hello. I am new to this site and am wondering if anyone can help please? I am on 150mg of Eltroxin and have been for 6 years, and have Hashimoto's (although doctor said Graves). I feel unwell nearly all the time and am trying to find a way to help myself feel better. I have an appointment with the doctor later this week. I have recently had more blood tests which show TSH 0.13 (0.35 - 5.5), FT3 4.60 (3.5 - 6.5), FT4 20.10 (10.5 - 20)?

Can anyone explain to me what this means please? Thank you.

8 Replies

It looks to me like you are on a good dose of Eltroxin. Most people feel best when their TSH is below 1 or even below range and with their FT4 at the top of the range or maybe slightly over (like yours). However, your FT3 (which most doctors don't test) is lowish in the range and this may be the problem. It could be that you are not converting the T4 (Eltroxin) to T3 very well.

It may be that you would be better on T3 (liothyronine or cytomel) or a natural dessicated thyroid such as Armour.

It could also be because of vitamin/mineral deficiencies. It is a good idea to get serum iron, ferritin (stored iron), vitamin B12, folate and vitamin D checked as they can cause symptoms in their own right and also affect how well your cells can use the thyroid hormones.

Check this page for more information on supplements on the main Thyroid UK website

Another issue could be low cortisol levels. If your cortisol levels aren't idea you won't be converting the T4 to the active T3 nearly as well as you should be, which would explain why you still have symptoms.

There is also the possibility that you are taking too much Eltroxin but you would feel better if you reduced the dose and pretty much straight away. You will likely know if it's because you are taking too much, too little or it is something else.

The main Thyroid UK website has loads of information about thyroid disease and treatments etc.

I hope that helps a little

Carolyn x


Thank you Carolyn. This is helpful I have had vitamin/minerals tested also. They were

Serum ferritin38.40 microg/L

Serum Iron13.40 units

Serum vitamin B12321ng/L

Transferrin saturation index25%

Plasma albumin level45 g/l

Plasma alk phosphatise level174 iu/L

Glucose level5.40 mmol/L

Magnesium0.81 mmol/L

Plasma C reactive protein 7.50 mg/L

Vitamin D 29.7 (30 - 79)

Cortisol (only taken once at (fasting) 248 nmol/L

Thyroid peroxidase anitibodies 195IU/ml

TSH receptor antibod level 0.42 U/L

TSHR antibody - borderline positive

I am taking 4000 iu a day of Vit D and am at the point where the doctor has said that the Endocrinologist has said (whom I have never seen) that I do not need T3. However, I struggle each day to keep going - am so tired, aching joints etc etc

I just wonder if you think that maybe I should ask again for T3? Any suggestions would be welcome.


Your ferritin is low. I can see that even without reference ranges. I think your serum iron is within range but I'm not sure as there is no reference range. You may benefit from iron supplements, making sure to also get enough vitamins C and B2 (riboflavin).

Your B12, although in range, could be higher. This would probably improve how you are feeling too.

Your vitamin D is also low. You need to keep taking the supplements. This could be contributing to your pain and fatigue and other symptoms. It did with me and I saw a big improvement once my level was higher.

I believe your cortisol is towards the bottom of the reference range for morning draw. I think it is best near the top of the range, but you will need to clarify that with someone who knows more about it. It is also difficult to tell without the actual reference ranges for this lab.

I'm afraid I can't comment on the others because there are no reference ranges and I don't know enough about them, but there is enough to be going on with; your iron, possibly B12 (and maybe folic acid) and your vitamin D.

I don't know about the cortisol. You may want to consult someone like Dr P or perhaps someone else here knows more. You might want to look on the internet about how to regulate your cortisol levels. There is a lot out there if you search "adrenal fatigue" or "adrenal insufficiency".

It might be that you do need T3 or NDT. It could help with the cortisol levels (adequate T3 is apparently needed for manufacturing cortisol). You do need to sort out the other things too though.

I hope you feel better soon

Carolyn x


Thank you so much Carolyn. That is very helpful. I will seriously consider seeing Dr P I think. I will see how it goes with my doctor on Friday.

Kathy x


Good idea. Please do let us know how you get on :)

Carolyn x


One other question please, as I have already had FT3 tested, is there a test to tell if I am not converting T4 to T3 very well?


There's tests for T3:reverseT3 ratio but I don't think it's usually available on the NHS. You may have to get it done privately if you want to know.


Yes, unfortunately it is not available on the NHS. If you want details of private tests, if that's an option for you, have a look here on the main Thyroid UK website

Carolyn x


You may also like...