Hi, wonder if you guys can advise me. I posted last week saying my Endo has allowed me to go onto combination T4/T3. I am currently on 142.5 ug levothyroxine. She is proposing reducing it to 100 ug daily, and adding Liothyronine 10 ug twice daily.
I am in the process of getting blood tests from Blue Horizon. Hospital tests I have so far are
Free T4 22 pmol/L (normal range 11-27)
TSH 0.60 mU/L (0.3-5.0)
T3 1.2 nmol/L (1.3-3.1)
Endo says says when an individual cannot convert T4 to T3 the TSH is usually high. Latest TSH low at 0.23 with T4 level of 23.
Please can I have some advice about this? Many thanks.
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LFE12
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Poor conversion is indicated by low TSH, high FT4 and low FT3. High TSH indicates under medication. 100mcg Levothyroxine and 20mcg T3 is equivalent to 160mcg Levothyroxine so your endo has given you a slight dose increase.
Is there a source for this info so I can show it to the Endo please. This is interesting, presumably meaning I have poor conversion? Figures as I have no thyroid due to TT and living on Levo for the past 17 odd years!
Low TSH can actually be responsible for poor conversion. Low TSH can be caused by many things, not just too much thyroid hormone. In your case I would say you need more T3.
I'll see if I can find anything about TSH and conversion.
Sorry to ask a stupid question. I always thought if the TSH number was low TSH was high, and vice versa. Feeling thick due to a sinus infection! And many thanks for response.
It's not a stupid question at all. The thyroid system is actually quite complex and many doctors don't seem to understand it well. I also probably didn't explain myself very well
Basically TSH is a pituitary hormone which signals to the thyroid to produce more thyroid hormones. If the number is high it means there is more TSH in the system. If it is low, there is not enough. When the TSH level is high this indicates that levels of thyroid hormones (T4 - or thyroxine- and T3) are too low and the body is trying to compensate by producing more TSH to tell the thyroid to work harder.
If TSH is high (too much TSH) then thyroid function is low (hypothyroidism).
If TSH is low (not enough TSH) then thyroid function is overactive and levels of the thyroid hormones (T4 and T3) are too high.
There are exceptions to this as TSH can be affected by other things such as pituitary dysfunction, stress and certain deficiencies. This means that you can have a low TSH even if your T4 and T3 are low (hypothyroid). This is the problem I have and I became very ill due to a particular GP not understanding this.
As well as TSH signalling to the thyroid to produce T4 and T3, the level of TSH affects the rate at which T4 is converted into T3 (the active form). The higher the TSH, the quicker the conversion (within limits) and the lower the TSH, the worse the conversion (again, within limits). My TSH is very low even when my T4 and T3 are well below range. I have appalling conversion and have to take T3 instead of T4 (levothyroxine).
I hope that clarifies things a bit but do ask if I haven't explained something very well
This is a great explanation, read together with the link you sent I think I get it! Does it all apply with no thyroid? Am I simply considered to be hypo?
Thank you so much for your time, much appreciated. I'm determined to get this right and not fail, as the Endo thinks I will.... Xx
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