Thyroid UK
82,993 members98,025 posts

Blood test for T3

Hi all

Just registered with a new GP. Not got much hope though as he won't discuss anything until I've had blood tests done and would only test for TSH and T4!!!! Feel like banging my head against a brick wall already.

I have so many symptoms weight gain even with calorie counting and gentle exercise. Extreme tiredness, hair loss, dry skin, heavy tired weak arms, moody, too name a few. My allergies are now bad since my TT. Interestly I didn't suffer with allergies before and now take allergy meds every day and had to rehome my dog as I couldn't cope with the fur, I'm sure its connected but he brushed that straight off.

Thinking of getting my own T3 test done as I'm sure I'm not converting my T4to T3. However what blood test do I need? T3 or T3RU?

Any help would be great before I go back to him. On a positive he said he would treat me and my symptoms not just my test results. Believe that when I see it though.

many thanks

6 Replies

Hello keb5332,

Sorry you are still not well. Are you still on Levothroxine?

Your doctor is right not to adjust dose without thyroid hormone blood test results but a shame she couldn't test T3.

I would say it would be well worth you getting T3 tested privately as together with your doctors tests you will get a clearer picure. Especially if you are concerned about a conversion problem.

Don't forget thyroid meds might not be absorbed properly if you have gut issues or vitamin deficiencies. Also it is very important to take pill first thing in morning on empty stomach with water, 1 hour before food, 2 hours before sups and 4 hours before iron and calcium.

Hope you feel better soon



He wouldn't test vitamins either so no idea how I'm doing on that front. I've been been range for ferritin before but he wasn't interested in testing that either!!! I have swapped my meds to the evening and I am finding that helps a little. Although lately I am struggling at around 3 in the afternoon and could easily sleep - which I do at the weekends but can't at work!!


Keb5332, you can order private FT3 tests from Blue Horizon and Genova via

I recommend waiting until you have your FT4 and TSH results because if TSH is high and FT4 is low FT3 will almost certainly be low too which would be due to undermedication rather than a conversion issue.

Thyroidless patients don't always do well on Levothyroxine only and if you do have a conversion issue the addition of some Liothyronine (T3) to Levothyroxine can be very helpful. Not all GPs can/will prescribe T3 without recommendation from an endo.

1 like

I'm pretty sure I am not converting well. I recently read that exercising uses up T3 from within the body. I started exercising gently but after a few weeks had to stop as I was absolutely shattered and it's taken me a few weeks to feel a bit better again. I do feel that I want to try something other than just T4 so let's see what the doctor says after the test results


Low calories also affects conversion. Not good for hypos! And in no way will it help you lose weight, because your weight gain has nothing to do with calories.



Have you considered adrenal fatigue?

The adrenal glands produce cortisol hormone inresponse to stress

(any stress, not just mental stress). So all of the above symptoms probably caused by an under medicated thyroid problem are causing mental and physical stress which inturn ups your cortisol production. Done over several years the cortisol looses to ability to turn off (high levels ) or runs low or reserves (low levels). Either will cause more problems with all your symptoms above and can even interfere with thyroid meds working.

Remember all hormones work in synergy.



You may also like...