Dosing - NDT vs Synthetic

[Nemi123]

Hi

My GP is not very good at this so he will probably say those results look great and leave the dosing to me.

I was using Armour 90mg (1.5grain) for 6 months but switched to synthetic as it was hard to get & expensive . My results on 90mg Armour were :

TSH 0.09 ( 0.5-4.6)

Ft3 5 (3.5-6.5)

Ft4 12 (11-23)

I’m on 10mg T3 (Thybon) and 50mg liquid T4 , feel slightly undermedicated but not very bad really. My results on synthetic:

TSH 0.88 ( 0.5-4.6)

Ft3 4.9 (3.5-6.5)

Ft4 12.5 (11-23)

I just wonder , should I try to raise my levo to 60mg or should I jump straight to 75mg? Never used synthetic before so I’m a bit unsure what’ a “normal” increase with this meds.

Thank You

[helvella Administrator Thyroid UK]

One of the benefits of levothyroxine oral solutions is the relative simplicity of making small dose adjustments.

Unless it is obvious a large change is required, such as if you were grossly under-dosed, I'd always want to do it slowly.

The larger the change you make, the more likely it is for you to go past your optimum dose.

The only reason for "normal" increases being 25 micrograms (or 12.5 if you split them or do alternate day dosing) is that is the dosage of the standard small tablet. There is absolutely no logic to it. (With T3, in the UK and Germany, dose changes are usually based on 20 micrograms - or half - or quarter - that, simply because we get 20 microgram tablets. In the USA and much of the rest of the world, they are based on 25 micrograms.)

[SlowDragon Administrator]

Suggest you increase by 12.5mcg levothyroxine ….50mcg and 75mcg alternate days

Or cut a 25mcg tablet in half to give 67.5mcg daily

Retest in 6-8 weeks

You should see increase in Ft4 and Ft3

[radd]

Nemi123,

If you were medicating 1.5 grains of Armour, then 10mcg T3 + 50mcg liquid levothyroxine risks leaving you quite under-medicated.

Literally 1.5 mcg Armour contains 57mcg T4 and 13.5mcg T3 but manufacturers claim 1 grain to be biologically equivalent to 100mcg T4, although I personally think it to be somewhere in the middle.

Now a days people new to thyroid hormone replacement meds often titivate with 12.5mcg T4 doses. However, as you are already used to medicating thyroid hormone and still quite a bit under dosed, if I were you I would increase Levo by 25mcg to 75mcg T4 asap and then retest in six weeks. Don’t forget to optimise iron & nutrients to ensure meds work best effectively.

[Nemi123 in reply to radd]

Thanks for all answers. GP was very concerned about synthetic T3, he said it would be stronger than the one I was used to from NDT but for me it feels feels a bit weaker. Strange how this works I think it's a good idea to up to 75mg T4 as well and if it feels too much then I can always drop to 60-65 after a week and retest after 6 weeks - I use liquid thyroxine (1 drop is 5mcg) so dosing is easy.