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Advice please on T3 dose (with T4) and blood test

I am currently taking 20mcg T3 with 150mcg T4. I started adding T3 8 weeks ago and increased weekly up to my prescribed dose of 20mcg which I have now been on for 5 weeks. I found a split dose during the day was leaving me exhausted so tried taking half my T3 before going to sleep at night. That didn’t really help so for the last 10 days I have been taking all of my T3 at night with my Levo. I still sleep ok, though have woken during the night for the last 3 nights, and don’t generally feel quite as tired during the day, compared to when I was taking T3 during the day, but still feel hypo and need to sleep in the afternoon.

2 days ago my GP decided to give me a blood test, with no prior warning. The test was at 9.30am and I had taken my T3 at 12.00am the night before and Levo at 10.30pm.

The blood results were as follows:

TSH 0.04 0.35 - 4.50 mIU/L

Free T4 13.90 11 - 22 pmol/L

Free T3 5.4 3.9 - 6.8 pmol/L

Blood results prior to addition of T3:

TSH 0.13 0.35 - 4.50 mIU/L

Free T4 18.6 11 - 26 pmol/L

Free T3 5.2 3.9 - 6.8 pmol/L

I am waiting for a follow-up appointment to see my endocrinologist and have been told it will likely be in 6-8 weeks time.

So, do I leave things as they are?

Is the latest blood test too early to make a decision?

Or should the blood test be a slight concern seeing as I had taken my medication less than 12 hours beforehand?

19 Replies

9 1/2 hours is OK for T3, and the T4 doesn't really matter. Your FT4 will be lower, anyway, now that you're taking T3. I would leave things as they are.

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I assumed one of the reasons for adding T3 was that FT3 levels would be higher than when on just Levo?

To save looking for one of my previous posts, FT3 levels on Levo only were as follows:

August 2017 - 175mcg Levothyroxine

Free T3 5.7 3.1 - 6.8 pmol/L

November 2017 - 200mcg Levothyroxine

Free T3 6.38 3.1 - 6.8 pmol/L

February 2018 - 200mcg Levothyroxine

Free T3 5.73 3.1 - 6.8 pmol/L


Normally, yes, they would. I don't know why yours isn't. Were both tests done at the same time of day? Because T3 has a circadian rhythm, too.

I take it you had poor conversion, and that was the reason you added T3?

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All of the tests prior to the latest were done at 8.00am with no meds for 24 hours.

No, the endo said it was cortisol related - we have had this discussion on another post - and the endo felt that because FT3 levels were dropping despite a constant dose of Levo there was no point in raising further.


Sorry, I don't remember the previous conversation, but I probably said 'so what is he doing about the cortisol?' Question still stands. :)

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I wouldn't expect you to but that's exactly what you said :)

The endo is doing nothing with regards to cortisol, however I take B vits, use good quality sea salt and have eggs most mornings but can’t supplement vit C as I have testosterone injections which cause above range haemoglobin and haematocrit plus high iron.


I'm so predictable! lol I do vaguely recall the conversation, now. If it were me, I would be taking him to task over his cortisol remarks, and demanding he does something about it!

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Reassuringly consistent is probably more approporiate!

So you think sit tight, wait 6-8 weeks and the lack of improvement in symptoms/FT3 levels will indicate cortisol levels need to be addressed or do I need to properly kick ass (bearing in mind he is NHS)?

Just out of interest could aching pain on both sides of my lower back be related to this?


I've not idea about the pain, I'm afraid. I didn't have any pain when my cortisol was low. But, I think your endo is stringing you a line with this cortisol business, it's just and excuse not to do anything, which is why I would take him to task. I'm not convinced that your cortisol has anything to do with it, one way or another.

However, I do think you should wait, because even with T3, it does take time to reduce symptoms - despite it's quick-acting reputation. You could feel a lot better in 6 weeks. Let's hope so, anyway! :)

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Do you fell you have more energy/better since T3 added?

Or no different?

Would agree with greygoose that you leave dose as is and wait to retest and see endo


I would say I sleep better but generally feel more tired. Brain fog, aches and pains, tight hands, clumsiness, low body temperature (average 36.1) are all still the same if not slightly worse.


As my FT3 level has not increased, even though bloods were taken quite soon after my last dose of meds, and symptoms are persisting, it seems a waste of my life to wait 6-8 weeks to potentially be told to increase meds or try something else. I would have thought any benefits of adding this dose of T3 would have materialised before now?


Your last tests luckily would not really be affected much by the 9.5 hours plus since you took the T3. Curious that your FT3 result is only 0.2 higher after being on full 20 mcg T3 for 5 weeks, did you get your levothyroxin reduced to 150 mcg, if so from what? I'm adding T3 to my T4 too but DIY, got to 25 mcg T3, but not sure if my levothyroxin was reduced enough so playing around with 100 and 75 mcg, to see which feels better, before testing bloods in c. 4 weeks. Why did the doctor add T3 as your previous results looked good on levothyroxin only?


I was on 200mcg Levo only.

FT3 levels were dropping and symptoms didn't improve.


What are your vitamin D, folate, ferritin and B12 levels like?

Has TT4 and FT4 dropped since dose of Levothyroxine was reduced?

You will need full Thyroid and vitamin tests really before deciding on next step.

Often seems Endo's are keen to reduce dose of Levothyroxine by too much.


Ferritin is low - 42 ug/L - but Iron, UBC, TIBC and Saturation are all optimal.

When last tested, Total vitamin D was 109.4 >49.9

B12 1128 ng/L

Folate 14.9 ug/L

TT4 has never been tested so if it was tested now I have nothing to compare.

FT4 has dropped

What other vitamin tests are required?


Ferritin must be higher for T3 or T4 to work

Folate looks low - do you have the range?

When were folate, B12, vitamin D last tested. They may be lower now due to reduced Levo

How low was FT4 (include ranges please )


Have you read my post?


Sorry forgot you had results of FT4 at start of post

Considering you took Levo the night before test (normally would delay until after test), yet your FT4 is still right at bottom of range

Suggests you might be better on slightly higher dose of Levothyroxine. Perhaps could try increase in Levo back up by 25mcg.


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