Free t4 or free t3?

[sunsetalley]

Which one is more important? I mean Levels of which one can affect overall health more?

Thanks in advance...

[Nanaedake]

T4 is a pro-hormone and without enough you can't produce enough T3 so both are important.

If a person is taking thyroid hormone medication then the levels of hormones expected or required will vary dependent on the type of thyroid hormone the person is taking. So the answer to your question could vary in any given situation.

[sunsetalley in reply to Nanaedake]

Thank you for replying.

So for someone taking t4 without conversion problem maitaining sufficient levels of free t4 is as important as free t3?

[Nanaedake in reply to sunsetalley]

Yes, when taking only levothyroxine, you need enough LT4 (thyroid hormone) to produce enough active T3. Sufficiency of thyroid hormone medication is indicated by TSH, FT4 and FT3 measurements. I'm not medically qualified or a scientist, so this is my understanding as someone with a thyroid condition.

As SlowDragon says, there can be factors that affect thyroid hormone utilisation, absorption or conversion. If you're having problems, you need to rule out these factors.

[SlowDragon Administrator]

Essential to test vitamin D, folate, ferritin and b12. If any of these are too low we can't utilise FT4 or FT3

Very important to test both TPO and TG thyroid antibodies at least once

If antibodies are high this is Hashimoto's, (also known by medics here in UK more commonly as autoimmune thyroid disease).

About 90% of all hypothyroidism in Uk is due to Hashimoto's.

Low vitamins are especially common with Hashimoto's. Food intolerances are very common too, especially gluten.

Link about thyroid blood tests

thyroiduk.org/tuk/testing/t...

Link about antibodies and Hashimoto's

thyroiduk.org.uk/tuk/about_...

thyroiduk.org.uk/tuk/about_...

Understanding Hashimoto's

hashimotoshealing.com/under...

List of hypothyroid symptoms

thyroiduk.org.uk/tuk/about_...

[RealEyes in reply to SlowDragon]

Thanks for the info SlowDragon

[Angel_of_the_North]

You need to know both, but FT3 will have more effect on overall health

[sunsetalley in reply to Angel_of_the_North]

T3 is more potent than t4 but I think at the end it's t4 that manages everything when there's no conversion problem. I suppose having normal levels of free t3 with low levels of free t4 leads to low levels of free t3 after awhile and brings back all symptoms of hypothyroidism.

[jgelliss]

@ sunsetalley , FT4 FT3 are both very essential markers for us . Some of us manually need to add some T3/NDT if we don't convert well T4 to T3 . Some T3 is also converted from T4 . We have receptor sights in our bodies that use both T3 and T4 . The receptor sights take what each one needs . Most of our T3 comes from T4 conversions . Nutrients are very vital for our thyroid meds to work well for us .

SeasideSusie has *Excellent* posts that are very valuable you may want to read .

SlowDragon has *Great* posts that are very valuable too .

[sunsetalley in reply to jgelliss]

Thanks for your reply🙂

[jgelliss in reply to sunsetalley]

Your most very welcome .