FT4/FT3 question - slightly confused!

[Nat_16]

Hi all!!!! :)
Ok so, I had more labs done and got the results from the dr today.  Results were:
TSH 8.1 (0.40 - 3.50)
FT4 12.7 (10.0 - 23.0)
FT3 5.2 (3.9 - 6.8)

Ok so now to my question.  I understand that T4 is converted into T3...so, if my T4 levels are low like they are now....how can my T3 result be so good?  If T3 is made from T4 and since my T4 result is considered low wouldnt that mean my T3 should be low or near the lower end of the range because there isnt as much T4 as I should have?????  

[Super_sally888]

Hi,

Your thyroid also produces T3, not just T4.  Also some of the T4 is converted to T3.

Your FT4 is low in range.  Your FT3 is only mid range.  So it is not 'so good', it is only just average.

Your results how you are hypothyroid and you need to be on thyroid meds.

Are  you on meds already.

[Nat_16]

Hi,
Yeah I have been on T4 meds since march this year.  There was an attempted increase maybe 8 weeks ago where my endo (who I no longer see) told me to go from 50mcg straight to 100mcg daily in one hit...that wasnt a good idea, had to go back to the original 50mcg after heart palps and high BP after taking the 100mcg for 7 days.
After I got these results today, the GP has advised me to take 50mcg one day 75mcg the next and keep alternating until the next lot of tests in 6 weeks.  I start the alternating increase as of tomorrow morning.  

The dr said the T3 was quite good because its in the higher half (as in it is closer to the upper limit than it is to the lower limit).