Is Free T3 A Good Measure Of Thyroid Function When Taking NDT?

[Connor888]

Just wondering because i'm sure the blood tests were made for T4 medication only. I'm not sure if I should wait to do another blood test before upping my dose or not, I feel a lot better but not quite there yet and my hands and feet still get cold. What would you guys do??

 

[wintagal]

Has it been 6 weeks since a change in your medication? It takes a while to build up in your bloodstream.

 

[Connor888]

Has it been 6 weeks since a change in your medication? It takes a while to build up in your bloodstream.

I've been upping it by 1/4 grain per week, although i haven't upped it this week in case i got a blood test

 

[wintagal]

Way too fast. You're using one of the most powerful and complex hormones in the body. How many micrograms in 1/4 tablet? What are the half-lives of t3 and t4? Are you tracking your temps and pulse 3x per day? My naturopath requires these things.
You're evaluating your subjective symptoms daily, when the dose won't be fully effective for weeks. Like driving 100 mph while steering using the rear view mirror.

 

[Connor888]

Way too fast. You're using one of the most powerful and complex hormones in the body. How many micrograms in 1/4 tablet? What are the half-lives of t3 and t4? Are you tracking your temps and pulse 3x per day? My naturopath requires these things.
You're evaluating your subjective symptoms daily, when the dose won't be fully effective for weeks. Like driving 100 mph while steering using the rear view mirror.

I'm increasing it by 9.5 mcg T4, 2.25 mcg T3 per week. It's your standard porcine derived NDT. Yeah I track my waking temperatures, but not my temps through the day very much. My temps through the day are usually normal so I don't bother, its just my waking temps that are low

 

[wintagal]

And back to your question - you're taking both t3 and t4 so you want to test free t3? Free t3 is very difficult to test when you're taking t3. It varies by the hour, depending on when your last dose was. It's more useful for someone taking no thyroid or only t4.

 

[Connor888]

And back to your question - you're taking both t3 and t4 so you want to test free t3? Free t3 is very difficult to test when you're taking t3. It varies by the hour, depending on when your last dose was. It's more useful for someone taking no thyroid or only t4.

I always left 12 hrs between my last dose of T3 & my blood test; but do you suggest temps and symptoms as a means of navigating dosages for someone on NDT then? Are you on t4 only?

 

[orewashin]

I took 30 mcg of T3 alone and my TSH was 9. I'm currently on NDT. A lower dose, I think. 15mg. I immediately felt brain fog from the very first dose. I currently need to take it for a comprehensive blood test for why I get brain fog, etc from T4. It's been almost 3 weeks and I have horrible brainfog. So I'm wondering, what did you feel from it at first, and what did you feel later?

As for the question, I wouldn't count on it. It's more obvious if you have issues on T4 alone, since T3 would be low, but NDT has small amounts of T3 that could mask issues on a blood test. If the T4 is getting converted into rT3 then you could still be hypothyroid despite T3 appearing normal.

 

[Connor888]

I took 30 mcg of T3 alone and my TSH was 9. I'm currently on NDT. A lower dose, I think. 15mg. I immediately felt brain fog from the very first dose. I currently need to take it for a comprehensive blood test for why I get brain fog, etc from T4. It's been almost 3 weeks and I have horrible brainfog. So I'm wondering, what did you feel from it at first, and what did you feel later?

As for the question, I wouldn't count on it. It's more obvious if you have issues on T4 alone, since T3 would be low, but NDT has small amounts of T3 that could mask issues on a blood test. If the T4 is getting converted into rT3 then you could still be hypothyroid despite T3 appearing normal.

Thanks

It varies from day to day, but when I first started my temperatures took a nose dive and I felt pretty awful. My temps returned to my pre-ndt temps after about a week and have stayed the same since (36.0 - 36.2). I don't seem to drop below 36 anymore which has been good,

Still have some brainfog & fatigue, but much improved; on 2.5 grains so far after 2 months, and I seem to be spending less time in bed

You took 30mcg of t3 at once? Is that safe? Thats an awful lot of t3

 

[orewashin]

Thanks

It varies from day to day, but when I first started my temperatures took a nose dive and I felt pretty awful. My temps returned to my pre-ndt temps after about a week and have stayed the same since (36.0 - 36.2). I don't seem to drop below 36 anymore which has been good,

Still have some brainfog & fatigue, but much improved; on 2.5 grains so far after 2 months, and I seem to be spending less time in bed

You took 30mcg of t3 at once? Is that safe? Thats an awful lot of t3

30 mcg per day. Which isn't a lot.

 

[wintagal]

You asked how to navigate NDT doses. The endocrinologists like to see TSH in normal range - .4 to 4.0 depending on the lab (US). That's regarding patients taking NDT or T4. The thyroid's TSH is very sensitive to exogenous T3 so your NDT dose may put it below range.
Your cold hands and feet could be due to anemia, low cortisol (which should always be tested when starting thyroid as the symptoms mimic thyroid), and many other things. It would be good if you stabilized your dose for a couple of months and evaluated pulse and temps. The body adjusts over time with changes and stability is important.

 

[Connor888]

Your cold hands and feet could be due to anemia, low cortisol (which should always be tested when starting thyroid as the symptoms mimic thyroid)

Yeah I had my cortisol, iron levels, vitamin D checked* and they all came back ok. My TSH was 3.3 pre-ndt, and while that's in the 'normal' range, I was in bed most of the day with those levels and felt pretty awful.

It would be good if you stabilized your dose for a couple of months and evaluated pulse and temps. The body adjusts over time with changes and stability is important.

Yeah, I definitely might start adding 1/4 grain every two weeks as opposed to every week. I've been taking my waking temps every day so I guess I will see when (if) my temps start rising :)

 

[wintagal]

3.3 is miserable. The ranges are too wide for most people. Also, the distribution is not normal ,but skewed toward the low end, so median TSH is closer to 1.5 than to 2. Many docs try to keep people 1/2 way through the range rather than closer to the low end. It doesn't work for many patients.

 

[Connor888]

3.3 is miserable. The ranges are too wide for most people. Also, the distribution is not normal ,but skewed toward the low end, so median TSH is closer to 1.5 than to 2. Many docs try to keep people 1/2 way through the range rather than closer to the low end. It doesn't work for many patients.

Yeah that's true, I think the reference ranges are far too broad as well. In 2018 when I was 20, I had a check up at the docs because I didn't feel well. They ran a bunch of stuff including my thyroid, and looking now, I can see my FT4 at the time of that test was (20) with a reference range of (10-20). Had I of been 1 point over, they might have looked into it.. But I was still within their ranges

Can I ask you how quickly your naturopath went about increasing your dose? It's 4-6 weeks for your tsh to follow after an increase right?

 

[wintagal]

That's what the endocrinologist did. The naturopath endocrinologist put me on t3 only after testing my rt3 (on t4) for 3 years and getting high out of range results no matter what we tried.