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What Do Free T3 And Free T4 Tests Mean?
Hi
I've just got my Thyroid Profile done for Hypothyrodism (suspect). Not sure why the Doctor didnt order the T3 and T4 tests instead of free T3 and Free T4.
TSH is 5.443, Free T3 is 2.58, Free T4 is 0.932
am aware that high TSH indicates hypothyroidism. However am not so clear about the the free T3 and free T4. Kindly advice.
I've just got my Thyroid Profile done for Hypothyrodism (suspect). Not sure why the Doctor didnt order the T3 and T4 tests instead of free T3 and Free T4.
TSH is 5.443, Free T3 is 2.58, Free T4 is 0.932
am aware that high TSH indicates hypothyroidism. However am not so clear about the the free T3 and free T4. Kindly advice.
Wed, 30 Jul 2014
Hello and welcome to HCM,
Total T3 and total T4 measures bound and unbound T3 and T4.
It is the free form of T3 or T4 which is active.
Rest of T3 and T4 is bound to proteins and is not active in body.
The effect of thyroid hormones is due to free T3 and free T4.
Thus, free T3 and free T4 are actual representative of thyroid functions rather than total T3 and T4.
Thanks and take care
Dr Shailja P Wahal
Total T3 and total T4 measures bound and unbound T3 and T4.
It is the free form of T3 or T4 which is active.
Rest of T3 and T4 is bound to proteins and is not active in body.
The effect of thyroid hormones is due to free T3 and free T4.
Thus, free T3 and free T4 are actual representative of thyroid functions rather than total T3 and T4.
Thanks and take care
Dr Shailja P Wahal
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