What is T3 andT4 I’ve been taking Levo for 5 years and I’m currently on 175mg

[Melpool2005]

Hypothyroidism

[fuchsia-pink]

If you are on levo, you have an under-active thyroid. This is primarily detected by checking TSH - thyroid stimulating hormone - which is a message from the pituitary to the thyroid telling it, in general terms, to work harder (giving a higher TSH) if it isn't doing enough (and you are hypo or under-active).

But to tell if the thyroid (a) receives this message and (b) acts on it, it's also important to look at your actual thyroid hormones too. You thyroid produces T4 which is inactive and needs to convert into T3, the active thyroid hormone needed in every cell in your body. Free T4 and free T3 measure how much hormone is available to do this - which is why you will see so many posts setting out these results.

Generally if we're hypo, we need both of these to be nice and high in their reference range - not crawling around the bottom of the range. Your GP will often test free T4, but because some people (like me) don't convert well, it's important to test free T3 as well - but the GP or labs wont often do this, which is why you see so many posts here about private testing too.

If you're new to all this, can I recommend a good rootle around the hypo section of the main Thyroid UK site - and a look at helvella 's excellent glossary [saved in "pinned posts"]

And if you post your latest blood results (and lab ranges which vary from lab to lab) the lovely people here can help you to understand them x

[DippyDame]

Lots of valuable info here, hope it helps.

thyroiduk.org/if-you-are-hy...