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Thyroid UK
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help to interpret lab results, please

I have had labs on both Armour Thyroid (5 grains daily) and Erfa Thyroid (5 grains daily). I had been on both drugs for three months before going to the lab (in June and September 2015 respectively). These are the results:

Armour (5 grains):

TSH <0.01 (ref 0.2-4.0)

FT4 1.1 (0.8-1.8)

FT3 2.9 (2.2-4.2)

Erfa (5 grains):

TSH <0.01 (same ref ranges)

FT4 1.1

FT3 4.1

I always go to the lab 24 hours after taking NDT.

My FT3 levels were at the upper normal range 24 h after taking Erfa, but barely midrange 24 h after taking Armour. Should I interpret this to mean that Armour does not work optimally for me, or that I am overmedicated on Erfa? I guess those results mean that my FT3 levels are twice the upper normal range right after taking Erfa...

Would it be a good idea to have labs right after taking Armour Thyroid, instead of waiting 24 hours? Or should I raise the dose? Or just forget about Armour, and go for Erfa instead?

5 Replies

Erfa is the one that appears to be giving you a higher FT3 at the top of the range and it is FT3 which is the most important range.


OK, thank you!


Anna69, FT3 was much better on Erfa which is surprising because there is slightly less T4 and T3 in Erfa than in Armour. Anyone taking T3 is temporarily overmedicated for a few hours as the T3 dose peaks, that's the way T3 works. I was told +20% after 24 hours which would make your estimated circulating FT3 4.92 max, and lower in between doses as T3 leaves the blood stream. If you measure thyroid levels within a couple of hours of taking NDT you will see high FT3, and possibly high FT4, as the T4 and T3 peak in serum. A member's FT3 was 15 a couple of hours after taking 2.5 grains and 5 after leaving 24 hours.

You should choose the brand you felt best on. If that's Erfa and you feel overmedicated with FT3 4.1 reduce dose.


I am not a medical professional and this information is not intended to be a substitute for medical guidance from your own doctor. Please check with your personal physician before applying any of these suggestions.


OK, thank you! No, I actually feel very well on my current dose of Erfa. Armour has not worked for me, unfortunately, as that is the brand favoured by my hormone doctor. Luckily, Erfa is readily available in several Belgian pharmacies. I understand that is also the brand prescribed by the doctors in Thierry Hertoghe's Brussels clinic...


Anna69, flipping doctors with their 'preferred' brands :x What best suits the patient should be the preference.


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