TSH F4 question

[Linsue56]

I haven't had an out of range TSH. 3 years ago on testing my TSH was 1.37 and my T4 was .9 the normal range with that lab said .8 was the normal range. I don't remember what the lab used for upper reference number.

I recently saw a different doctor he checked my TSH but wouldn't check my
t3 or t4. The TSH was 1.74 still in the normal range. My question is on the T4 on previous test it was close to the bottom of the range. Does the T4 go down if the TSH goes up or are they unrelated? If they are unrelated then I am not going to push for getting my t3 and t4 checked. I am seeing a new doctor soon and thought I might bring it up depending on how the numbers work.
thanks for any information on this.

[GD Women]

Yes, in normal cases F/T-4 and F/T-3 goes in the opposite direction of TSH.

You want the FT's (Free) checked not the T's (Total).

If you do another test with a different Lab and its questionable, then recheck with another test in 6 weeks for verification. A lot can interfere with the test causing false levels.

However, if your TSH is good but there is a question about the FTs, it might not be a thyroid issue, but something else going on instead. When serum FT4is in the normal range, it is almost invariably in the lower part of the range in those with nonthyroidal illness.

TSH relates to whether a person is hypo or hyper and needs treatment.
F/T-4s test tells whether the thyroid is performing properly.
A total or free F/T-3 test determines whether the thyroid is performing properly. On how the FT's relate to each other, can relate other issues as well.

Good Luck!

[Linsue56]

Thanks for the answer. I wasn't aware T3 and T4 can be low from problems other than high or low thyroid.