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Labs: Low(ish) TSH but low(ish) FT4

2385 Views 3 Replies 4 Participants Last post by  andyb1205
Hello, folks --

Would like some feedback on my lab results, as I was only recently diagnosed as hypothyroid. I'm a 38 year-old man. When I was diagnosed about six weeks ago, my labs were as follows:

TSH: 0.745 (range: 0.270 - 4.200)

FT4: 0.92 (range: 0.93 - 1.70)

My doctor prescribed 75 mcg of Synthroid, which I have been taking for about six weeks. I feel significantly better than I did -- less cold, less sore, I can actually get out of bed in the morning, and I can work out a little. But, I feel like a lot of the symptoms are still present, just decreased.

I now have a new set of labs from a couple days ago. My TSH decreased and my FT4 increased. By the way, no, my doctor didn't run any other thyroid tests.

TSH: 0.351 (range: 0.270 - 4.200)

FT4: 1.19 (range: 0.93 - 1.70)

My doctor reluctantly, at my request, increased my Synthroid to 88 mcg, but said he was concerned about my TSH level getting too low.

Does this all seem correct to you thyroid gurus out there? I realize my TSH is on the low end, but it seems strange that my FT4 wouldn't increase more -- almost like I'm both marginally hypo and marginally hyper. Should I even be concerned about TSH if T4 could still stand some improvement? Any advice? I am very interested in any feedback or opinions on what the issue might be, or how others in a similar situation have been treated successfully.

Thanks in advance.

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FT4: 1.19 (range: 0.93 - 1.70)
Goal is to have FT-4 fall between 1/2 and 3/4 of range which for your range is (( 1.31- 1.507))

TSH is a pituitary hormone and can lag up to 6 weeks.

You might consider asking for a Free T-3 test which will confirm you are converting properly, which means your T4 hormone replacement pill is converting from Free T-4 to Free T-3. You should be pushing 3/4 range for both tests.
I would also ask for a thyroid antibody panel; usually when we see a low Free T4 we see and high TSH and yours is the opposite. Antibody activity might explain that.
I second checking antibodies, but it's also possible you have central Hypothyroidism. Check out these two peer reviewed articles, the first one is titled: Central Hypothyroidism: A Neglected Disorder, by most cited scientific journal in the world. Inappropriately low or normal TSH with below range or in bottom part of range Free T4 is indicative of this.

The TSH, which is a pituitary hormone and signal, is not working or not working properly. Hence in your case the T4 is not rising as much as it should considering your TSH.
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