What does FT3 blood test result show?

I have just got back from my GP. My TSH, FT4 and FT3 are all low. He has just told me the reason why my TSH is low is because I am taking too much T3 (40mcg).

When I pointed out that surely if I were taking too much T3 my FT3 results would be high instead of low, he replied that the FT3 results only show how much is in my body naturally. In other words, what my body is making. The 40mcg that I am taking daily is an artificial dose and will NOT come out in the blood tests.

I am baffled!!!

9 Replies

Ha ha ha ha ha .... HeS having a laugh and talking rubbish. In fact it's so rubbish that you should report him for incompetence.

Basically, I think he doesn;t know why my TSH is low but my FT3 and 4 are also low. It doesn't make sense but he doesn;t seem to want to find out either!

This is a link which you may find helpful. If you want to reply to a comment you have to press the blue Reply to this otherwise the person is emailed.

Your TSH is low BECAUSE you are taking T3, it doesn't matter how much. Taking T3 lowers the TSH out of proportion and it no-longer reflects thyroid status. That's why we say it is a useless test and shouldn't be used to dose by. If your frees are low, you need an increase. He is an idiot. change doctors, quick!


How come he has the only blood test that easily distinguishes between the thyroid hormone you make and the thyroid hormone you take? The only one on the whole universe!


Is there an article I can take to him to show him he is wrong?

An article to show him that he's wrong about blood tests not measuring the 'artificial dose'? I very much doubt it! Frankly, this GP sounds as if he's going to need re-training before he's of any use to you. In fact, I'd be questioning whether he really does have any medical qualification at all!

Please either see a different GP or tell him to refer you (back?) to a specialist.

I don't suppose anyone's ever thought about such a thing before, so they wouldn't have written about it. He must be making it up as he goes along. But at least he gets 10/10 for originallity!!! lol

I generally try not to be toooo harsh on GPs when it comes to thyroid issues, because they don't have the in depth training that a supposed specialist has. This GP however is obviously not simply inadequately trained in the complexities of thyroid, but is a complete idiot from the ground up. If the blood test doesn't measure the amount of exogenous thyroid hormone, then what on earth would be the point in doing the tests at all!

Your GP either needs to offer you an increase in your thyroid medication, or refer you back to a specialist... preferably one that understands how to interpret thyroid blood tests :)

You may also like...