Confused over recent lab results since starting... - Thyroid UK

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Confused over recent lab results since starting Armour


Hi all,

I switched from 87.5mcg of levo last November to Armour and I am currently taking 1 grain. After a bumpy start, things really improved and I felt well over the Christmas period. My TSH in December was 3.9 (range 0.99- 4). Over the last week or so I have felt gradually worse and my latest results have come in leaving me feeling confused. My TSH is 2.0, FT4 11.8 (12-22) and FT3 3.8 (3.4-5.8) my last FT4 and FT3 was 19.1 and 4.1 respectively. I am confused as to why my TSH hasn't gone up if my T4 and T3 has dropped. Also the equivalent dose of Armour 1 grain is 75-100mcg of levo thyroxine, therefore if I increase armour I will be taking way more t4 than I could ever take previously without going hyper. Any help would be appreciated.

10 Replies

Human thyroids secrete T4:T3 in about a 10:1 ratio. Armour is about 4:1. Your low T4 reflects your new medication. The way to even things out would be to combine T4 + Armour. Your labs on 87.5 levo weren't that bad, but I'm guessing you wanted a little more T3. You could've dropped back to 75 levo, and added in 1/2 grain Armour to start instead of switching to 1 grain, which only has 38 mcg T4. Your T4 dose was dropped by more than half when you switched!

The error in thought here is thinking 1 grain Armour = x amount of levo, when there really is no such equivalency. The body uses T4 for some things and T3 for other things, so you can't make conversion equivalencies (though the medical profession has!). It's like comparing apples and oranges.

Here's an explanation of how to do the math to figure an approximate dose:

Since your T4 is below range, it would make sense to hold your 1 grain dose and add the smallest amount of T4 to start, or 25 mcg. Then titrate up slowly as future labs and symptoms suggest.

Frazzie1 in reply to HIFL

Thanks so much for getting back to me. Someone else suggested that adding in levothyroxine was not the way forward even though it does make sense in some instances. What I might do is gradually increase the armour and see how I get on with that then. I can see now that they are two different drugs and difficult to compare. Is it true that one responds quicker to armour that synthetic thyroid? I am sure I have read that somewhere. Although my numbers were reasonable on levo, I felt unwell most of the time. My hair never stopped falling out at that dose and I felt chemically driven. I actually don't think I do that well having a supressed TSH. I have a base line from years ago when I was pregnant at 1.7. Two years in I really thought I had a plan and strategy that would work..... you just have to keep at it I guess. I really appreciate your responses. Thank you

Or... :)

You could increase your Armour by another quarter to half grain. If you couldn't tolerate Levo, I'm not sure it's wise to reintroduce it.

The thing is, TSH isn't nearly as an "exquisite" or precise measurement as many doctors and lab technicians declare it to be. It can bounce around all over the place. For example, the results of a blood test taken at 8am can be very different to one taken at 3pm. About the best you can hope with with TSH is a trend. Looking at your numbers though, I'd say you've got a way to go with dosage.

As HIFL said, you can't really do equivalents with NDT, though many try. Generally you will need more Armour than you did Levo.

I will increase slowly over the next two weeks and see if I can pick things up a bit. This is the lowest my T4 has ever been even prior to being started on levo-no wonder I feel so bonkers. I feel encouraged now that I can increase the armour and have some scope to do so. talk to isn't it!At least I can write down exactly the symptoms I have and know they occur when I am hypo. I wasn't sure if I had gone the other way to be honest as the symptoms are similar. I have had 3 terrible crashes over the last week (like very low blood sugar) and I remember now that this happened to me last summer when I went hypo again on 75mcg of levo. I wonder what an average dose of Armour is?

Thanks for responding though. Its so reassuring to have someone to discuss this with.

Have a look at my most recent post. I had very similar bloods to you after 6 wks on 1 grain of Erfa. I have now increased to 1.5 grain and intend to increase to 2 grains after a month if I feel no better. Good luck

I've read somewhere - brain fog tonight, I can't remember where! - that most people end up on a dose between 2 and 3 grains.

They aren't directly comparable. Its normal to have low TSH while on NDT because you are supplementing directly with some T3. You really need to look mainly at free T3, which for most people needs to be towards the top of the range for them to feel OK.

Hi T4 does go down if treated with any T3 ie NDT. Tghe Ft3 is more important. That is lowish. I think you need more armour, 1 grain is a tiny amount. Try 2 grain and repeat test in 6 weeks.


Frazzie1 in reply to Jackie

Thanks Jackie. I have upped my dose by another 1/2 grain which I am taking in the afternoon. Haven't had a hypo today so that's an improvement!

Hi T4 does go down if treated with any T3 ie NDT. Tghe Ft3 is more important. That is lowish. I think you need more armour, 1 grain is a tiny amount. Try 2 grain and repeat test in 6 weeks.


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