A very clever person on here worked out the likely mcg of T3 & T4, contained in 3.5 grains of NDT from Thailand. Unfortunately I've mislaid the post.
I'm seeing my endo on Wednesday and I want to understand why he put me on such low doses of Synthetic T3 & T4 for eight weeks. The new blood tests bear out my symptoms. New readings show T3 down at 3.1; T4 down at 8.1; TSH up at 0.05.
You might also wish to look at my world desiccated thyroid document.
helvella's medicines documents (UK and Rest of the World) can be found here:
helvella - Thyroid Hormone Medicines
helvella has created, and tries to maintain, documents containing details of all thyroid hormone medicines in the UK and, in less detail, many others around the world. There is now a specific world desiccated thyroid document.
I highly recommend viewing on a computer screen, or a decent sized tablet, rather than a phone. Even I find it less than satisfactory trying to view them on my phone.
helvella - Thyroid Hormone Medicines - UK
The UK document contains up-to-date versions of the Summary Matrixes for levothyroxine tablets, oral solutions and also liothyronine available in the UK. Includes descriptions of tablet markings which allow identification. Latest updates include all declared ingredients for all UK products and links to Patient Information Leaflets, etc.
Contains details of all levothyroxine, liothyronine and combination products - excluding desiccated thyroid products. Details available vary by country and manufacturer.
The link below takes you to a blog page which has direct links to the documents from Dropbox and QR codes to make it easy to access from phones. You will have to scroll down or up to find the link to the document you want.
NDT comes in grains. Generally, 1 grain is 60mg and contains 38mcg of T4 and 9mcg of T3. Some brands have 65mcg. Equivalence charts show that 1 grain of NDT has the approximate equivalence of taking 100mcg of levothyroxine. Ensure that you discuss dosages with your clinician.
So if you were on 3.5 grains - that’s roughly equivalent to 133mcg Levo and 31.5mcg T3
Now on 100mcg levothyroxine and 20mcg T3
Was this recent test done as recommended early morning, ideally just before 9am, only drink water between waking and test and last dose levothyroxine 24 hours before test
This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)
T3 ….day before test split T3 as 2 or 3 smaller doses spread through the day, with last dose approximately 8-12 hours before test
Maybe I'm being a bit dumb, but as I was on 3.5 grains of NDT, which was replaced with 100mcg of Levothyroxine, surely I'm considerably under-dosed in Levo (assuming 65mcg per grain)?
Doesn't the same apply for T3: if 1 grain of NDT equals about 30mcg of T3, then I am considerably under-dosed here too?
My apologies, SlowDragon. I'd overlooked the values you use in converting NDT to T3 and T4. There's such a wide range of opinion on this subject, it's easy to become confused😵💫
Beware of comparing the content of NDT and synthetic hormones. Levothyroxine absorption varies considerably but is I guess around 60%. I haven't seen any information on the absorption of T3 or T4 for NDT.The manufacturers state that one grain of NDT is equivalent to 100 mcg levothyroxine. I haven't seen any evidence for this but assume it is true as Forest Pharmaceuticals make both Armour and Synthroid.
But the equivalence used has been set in stone for decades. Many members who have switched (either way) have felt the one grain of NDT is closer to something like 65 to 75 micrograms of levothyroxine.
That isn't a big deal when changing to NDT - it would just mean starting out a bit low. But is a real concern for anyone switching from NDT to levothyroxine - when they could end up significantly over-dosed.
Opinion is certainly divided on the equivalence to Levothyroxine. T3 is more consistent. Either way, I went to an endo when on 3.5 grains of NDT, displaying quite severe symptoms of Hypothyroidism, and he gives me a lower dose of both.
Does anyone have a view regarding the other results I posted?
The manufacturers haven't referenced research for their numbers. I found this commentary from Dr Westin Childs restartmed.com/thyroid-medi... . I'm not a fan of him but a casual glance suggests it is a useful document.
I tend to agree with his eventual suggestions (not from personal experience but from what many others have posted) - but he uses an awful lot of words to get there!
And why does he (and so many others) bother with separate columns for multiple NDT products which all have the same (at least, nearly the same) hormone content?
Maybe I'm being a bit dumb, but as I was on 3.5 grains of NDT, which was replaced with 100mcg of Levothyroxine, surely I'm considerably under-dosed in Levo?
Doesn't the same apply for T3: if 1 grain of NDT equals about 30mcg of T3, then I am considerably under-dosed here too?
Although I've tended to believe the manufacturers' claims that 100 mcg levothyroxine is equivalent to 1 grain of NDT I've had a think about it. I suspect this was very roughly true and rather than bother with lots of checks and ending up with an odd dose e.g. 87 mcg or whatever, they simply decided to round it up to 100 mcg.
We have to remember that TSH testing wasn't really around in those days and NDT content was somewhat variable. So, my suspicion is they just assumed 100 mcg was a nice number and good enough. This allowed tablets to be swapped on a one for one basis. It doesn't justify not giving an accurate conversion factor nowadays.
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