TSH to Free T3 ratio.

Hi,

I have a question but I'm not sure if there is an answer for it.

My labs free T3 range is 2.63-5.7 (5.7 being at the high end)

TSH is 0.3-4.94

I know the nos don't remain constant but what is the relationship between them. For example if you were halfway on the Free T3 scale would your TSH be halfway too? I've read that you should be in the upper 50% of Free T3 (which on my scale would be around 4.1+), others say you should be at 5.0-ish. What would a free T3 of 5 look like on this TSH scale?

I had a blood result and I was too high on Free T3 (5.5). Felt hyper. I was taking 2 grains and 15mg T3. I should have reduced by 5mg T3 I'm thinking (ended up reducing by too much) which would prob have moved me to around 4.5? I'm basing this because when I was on 2 grains and 20mg T3 my free T3 was 6.6. So there appears to be a drop of around 1.0 in free T3 when I drop 5mg T3?

Thanks,

The Hoggle

[Clutter]

The Hoggle, TSH and FT3 are entirely separate tests and there's no correlation between TSH and FT3 tests or ranges. Pituitary gland responds to low circulating thyroid hormone by increasing TSH. When sufficient hormone is detected TSH drops. Usually high TSH = low FT4 &/or FT3. Sometimes, high TSH and high FT3 will be seen but this isn't sustainable as there will be insufficient T4 for conversion to T3.

If your FT3 was 5.0 I would guess your FT4 to be at/near top of range and TSH to be suppressed <0.1. My understanding is that FT3 in the top third of range is desirable. Not everyone is comfortable with FT3 high in range so 4.5-5.0 may be good for you. I'm comfortable with FT3 >4.5 (3.2-6.2). I felt well with it at 8.4 but don't need it over range to feel well, besides which my hair was coming out in clumps.

We all react differently to dose adjustments which is why it is handy to to track results. I have mine on a Excel spreadsheet and can see what differences a Levothyroxine or T3 tweak has made and can project from that what difference a dose change is likely to make. It's possibly easier for me to do this as I don't have a thyroid gland.

Disclaimer: I am not medically trained. My advice is based on my personal experience &/or research and is not given in my capacity as an Admin of Thyroid UK or endorsed by TUK. Information on the forum is not intended to be a substitute for medical guidance from your own doctor.

[Hidden in reply to Clutter]

Yeah it's weird that each lab has different reference ranges! I've seen labs with 3.1 up to 7.8. Wish they would have a standard range across the board.