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

TSH FT4 male hypothyroid levothyroxine Synthroid low

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#1 freebooter



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Posted 11 January 2018 - 08:09 PM

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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#2 Lovlkn


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Posted 11 January 2018 - 10:06 PM



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.

Free T-4 and Free T-3 are absolutely necessary to properly dose yourself.
My experience is that 1/2 - 3/4 of range is your goal for optimal treatment

My Journey... 7 years to receive a diagnosis. TT 2004 after 4.5 years on Tapazole that had to be adjusted monthly - endo ran labs every 4 weeks. Remission was never going to happen for me so I opted for surgery to remove. Final DX by surgeon was Hashitoxicosis, TPO antibodies over 2000 and TSI 316% within the year prior to surgery. I never had a ultrasound or any lab testing to rule out cancer - pathology was negative. Post surgery I was kept hypo for many years - until I figured out how to dose my self, relying on where I fell in the FT-4 and FT-3 labs. I run TSH below range due to positive TBII antibodies. Horrible time adjusting to addition of Cytomel = patience pays off when adding this drug to the mix.

The happy ending ---> Stable dose since 1/10 Unithroid 125mcg, Cytomel 12.5mcg - labs I can live with.

None of the information on is intended to diagnose, treat, cure or prevent any disease. Information shared is based on my personal experiences and should not be considered medical advice. Please consult a physician before adjusting any medication.

#3 jenny v

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Posted 12 January 2018 - 03:52 AM

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.

Thyroid problems since 2002
Diagnosed with Graves Disease 2002 and Hashimoto's Disease April 2012
TT on October 10, 2013
Currently on 90mg Westhroid and 50mcg Cytomel

Information exchanged on these boards should not be construed as medical advice. We ARE NOT doctors. Please seek a qualified physician to answer your questions before acting on any information found here.

#4 andyb1205


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Posted 02 February 2018 - 08:42 AM

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.

Also tagged with one or more of these keywords: TSH, FT4, male, hypothyroid, levothyroxine, Synthroid, low

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