Thyroid UK
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Post as requested by clutter re optimal ranges of FT4/3

On 75 T4 5 times per wk +100 twice a wk. Blood test rslts:

TSH suppressed 0.04. FT4 16.4 (12-22) FT3 3.4 (4-6.8).

On these meds v tired plus bad neuropathy in feet and legs.

Endo agreed I have a conversion problem. Agreed to prescribe T3.

On 50 T4/20T3 Felt under medicated - TSH 0.03 FT4 7.9 FT3 4.9

Now on 50T4/30T3. Still tired.


Looking at thyroxine only rslts was T4 at optimal level and should thyroxine have been reduced before adding in T3.

Had blood test last wk - tk T3 18 hrs before and thyroxine 24 yrs before, Not had rslts yet.

Any help /advice gratefully received.

2 Replies

Caze, FT4 often drops when taking oral T3 because there isn't the need for higher levels to convert to T3. Your TSH and FT3 results on 50 T4 and 20 T3 looked fine. The extra 10mcg T3 should push FT3 further up the range which may improve tiredness. I found *feel good* lagged behind good blood results by about 8 weeks, so hang in there.

Are your ferritin, vitamin D, B12 and folate good? Low/deficient levels can cause musculoskeletal pain, fatigue and low mood. Has the leg and foot neuropathy subsided on T4+T3? Neuropathy can be a sign of B12 deficiency.


Hi Clutter

Neuropathy improved greatly with addition of T3. Hve posted re this to tell others. B12 above rge. Ferritin was low but is improving with supplements. Vit D good.

In the past I tk as much as 150 thyroxine and I was fine fr yrs - lots of energy.

Then gradually thgs began to go wrong. Followed yrs of extreme stress. As my health deteriorated my T4 level shot up and my TSH became suppressed.

Now my TSH is suppressed on just a low level of thyroxine when both T4 and T3 are low. That's why I am wondering if I shd be on slightly higher T4

On 50/30 I initially had bad h/aches but had fr mre energy. The improvement fell away after a cple of wks at the same time the h/aches eased. I've noticed I dream a lot on T3.

I thght my T4 both before adding T3 looked on the low side - not optimal.

Am hoping to get a cc of my latest blood tests later. I'll post.

Thks again fr yr input - much appreciated!


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