Low TSH with mid range FT3

[PinkCat2023]

I'd recently gone from taking 50 mcg Levothyroxine per day to taking 75 mcg Levothyroxine per day. I take Tirosint, which is Levo with fewer fillers.

My fasting blood test results are as follows:

14 March 2024 - last taken Levo more than 24 hours prior to test

TSH 0.58 (0.27 - 4.2)

FT4 16.5 (12.0 - 22.0)

FT3 4.2 (3.1 - 6.8)

21 March 2024 - last taken Levo 5 hours prior to test

TSH 0.28 (0.27 - 4.2)

FT4 19.9 (12.0 - 22.0)

FT3 4.8 (3.1 - 6.8)

I'm curious why my TSH is so low, while my FT3 (which I think is supposed to give the feedback signal to TSH) is below mid range.

Might there be a T4 to T3 conversion issue?

Or and adrenal issue?

Or could it be something else?

My doctor has recommended I try to decrease my dose, as he said that, even though the numbers were in range, they may be too high for me personally. While on 75 mcg Levo, I started experiencing more heartburn, faster heartrate, diarrhea and anxiety. I've decreased my dose to 63 mcg per day and I've started feeling quite a bit better. I still feel I can do even better, if my T3 was higher / I had proper conversion to T3. I had so much energy at first, when I started my NDT in December 2023. Then my FT4 crashed, basically, and I had to come off it. So now I'm back to taking Levo but can't help but feel I have not yet tackled this thing fully. There's room for improvement still, I just don't know how to get there.

If you have any insights / experiences you'd like to share, I'd love to hear from you.

[greygoose]

FT4 16.5 (12.0 - 22.0) 45.00%

FT3 4.2 (3.1 - 6.8) 29.73%

Expressing the results as percentages shows that your conversion isn't that good. The gap between the FT4 and the FT3 is too wide. The FT3 should be just slightly lower than the FT4. But, you haven't got much T4 to convert. You are under-medicated.

21 March 2024 - last taken Levo 5 hours prior to test

And, as you can see, all you got tested was the dose you'd just taken. It you leave a gp of 24 hours you get a better idea of your normally circulating T4 level.

I'm curious why my TSH is so low, while my FT3 (which I think is supposed to give the feedback signal to TSH) is below mid range.

TSH is affected by both T4 and T3, the pituitary does not distinguish between the two. And it's not that low, anyway. Were both tests done at the same time of day?

My doctor has recommended I try to decrease my dose, as he said that, even though the numbers were in range, they may be too high for me personally.

Highly unlikely judging by your results on 14th March, your FT3 is very low.

While on 75 mcg Levo, I started experiencing more heartburn, faster heartrate, diarrhea and anxiety.

Could be due to low nutrients. Have you had your vit D, vit B12, folate and ferritin tested? All nutrients need to be optimal for your body to be able to tolerate the hormone you're giving it.

I had so much energy at first, when I started my NDT in December 2023. Then my FT4 crashed, basically, and I had to come off it.

What do you mean by your FT4 crashing? Why did you have to come off it?

[PinkCat2023 in reply to greygoose]

greygoose Thank you so much for your comments!

21 March 2024 - last taken Levo 5 hours prior to test

And, as you can see, all you got tested was the dose you'd just taken. It you leave a gp of 24 hours you get a better idea of your normally circulating T4 level.

Indeed. The test of 14 March was when I'd taken Levo more than 24 hours prior to my test. I wanted to make sure my levels were not to high soon after taking Levo, in case that was causing my symptoms, which I why I did my follow up test 1 week later, with Levo taken 5 hours prior to my test.

I'm curious why my TSH is so low, while my FT3 (which I think is supposed to give the feedback signal to TSH) is below mid range.

TSH is affected by both T4 and T3, the pituitary does not distinguish between the two. And it's not that low, anyway. Were both tests done at the same time of day?

Interesting, I did not know that re T4 signalling back as well. My test of 14 March was done at 08:55 am and my test of 21 March was done at 09:59 am (the second test place only opens just before 10 am).

My doctor has recommended I try to decrease my dose, as he said that, even though the numbers were in range, they may be too high for me personally.

Highly unlikely judging by your results on 14th March, your FT3 is very low.

My symptoms have decreased but I would tend to agree that something isn't quite right and I'd love to get my FT3 up if possible.

While on 75 mcg Levo, I started experiencing more heartburn, faster heartrate, diarrhea and anxiety.

Could be due to low nutrients. Have you had your vit D, vit B12, folate and ferritin tested? All nutrients need to be optimal for your body to be able to tolerate the hormone you're giving it.

Yes, most recent test results are from 14 March 2024:

IRON 14.0 (6.6 - 26.0) (down from 16.2 on 08Jan24 - was 5.3 on 24Aug23)

T.I.B.C 65 (41 - 77)

TRANSFERRIN SATURATION 22% (20 - 55)

FERRITIN 21 (13 - 150) (up from 14 on 08Jan24)

25 OH Vitamin D 89 (50 - 200)

Whole Blood Potassium 1810 (1450 - 2100)

Whole Blood Calcium 61.1 (48 - 65)

Whole Blood Copper 0.95 (0.8 - 1.65)

Whole Blood Magnesium 33.6 (29 - 42)

Whole Blood Manganese *12.5 (7 - 11) HIGH

Whole Blood Zinc 6.2 (4.0 - 7.6)

Whole Blood Chromium 0.2 (< 1)

Whole Blood Selenium 94.8 (85 - 200)

Vitamin B1 (Thiamine) 56.5 (15 - 70)

Vitamin B2 77.0 (40 - 140)

Vitamin B3 (Nicotinamide) 61.9 (8 - 100)

Vitamin B6 (pyridoxine) 25.9 (12.6 - 45.2)

Red cell folate 481 (340 - 1474.7)

Active B12 129 (25.1 - 165.0)

I had so much energy at first, when I started my NDT in December 2023. Then my FT4 crashed, basically, and I had to come off it.

What do you mean by your FT4 crashing? Why did you have to come off it?

My T4 was not optimal prior to starting NDT. I started feeling seriously unwell while taking NDT, so I wanted to see my levels after I'd taken it 4 - 5 hours prior to my test. FT4 came back as 12.4, which was pretty much the highest possible level of the day then, as I've understood it spikes a few hours after taking NDT. So it was probably even lower later in the day. I came off it because I felt miserable. I posted about taking NDT here: healthunlocked.com/thyroidu....

Thanks again for your comments, I much appreciate you taking the time to try to help me!

[greygoose in reply to PinkCat2023]

I wanted to make sure my levels were not to high soon after taking Levo, in case that was causing my symptoms,

But it wouldn't, it doesn't stay that high long enough.

I'd love to get my FT3 up if possible.

Then you're probably going to have to get hold of some T3 and take that with your levo.

FERRITIN 21 (13 - 150) (up from 14 on 08Jan24)

That is bad. But I'm not good on iron, so I would advise you to do another post just asking about that, so that those that know can advise you.

25 OH Vitamin D 89 (50 - 200)

Too low.

Whole Blood Magnesium 33.6 (29 - 42)

No point in testing magnesium because the results aren't reliable due to the way the body handles it. But if you're going to supplement vit D, you need to also take magnesium because the two work together. No problem. It's water soluble so excess - if there were any, which is doubtful - would just be excreted.

Whole Blood Selenium 94.8 (85 - 200)

This is low, and could be one of the reasons your conversion is poor. Have you tried taking selenium?

Red cell folate 481 (340 - 1474.7)

Low.

You might benefit from a good B complex. That is to say one that contains methylfolate and methylcobalamin rather than folic acid and cyanocobalamin.

I was trying NDT (Erfa) for a short while (probably just over a week) and wasn’t feeling well. I had my bloods tested but this was while taking NDT:

TSH 0.75 (0.27 - 4.2)

FT4 12.4 (12 - 22)

FT3 4.6 (3.1 - 6.8)

This is when I added 50 mcg of Levo (Mercury Pharma) to my daily routine and when the bloating increased and the heartburn really took off.

Well, if I've understood correctly, you tested too soon, increased too soon and gave up too soon. Of course TSH and FT4 were going to be low because of the T3 in NDT. But you were under-medicated there. Instead of adding levo, you should have continued to increase the NDT by 1/4 grain every two weeks or longer.

[PinkCat2023 in reply to greygoose]

greygoose Thank you for your reply.

I'd love to get my FT3 up if possible.

Then you're probably going to have to get hold of some T3 and take that with your levo.

I’d rather work on getting proper conversion from T4 to T3, if possible. Last time, my T4 went really low when I took NDT. Something is wrong there, so rather than trying to compensate for that by taking a medication similar to what made me feel so awful last time, I’ll try to get to the root and obtain better conversion first, to see if that helps.

FERRITIN 21 (13 – 150) (up from 14 on 08Jan24)

That is bad. But I’m not good on iron, so I would advise you to do another post just asking about that, so that those that know can advise you.

I’ll revisit a reply to one of my previous posts, in which SlowDragon kindly gave lots of information about ferritin. My ferritin has been lower in the past so it's already gone up. I'd like to get it much higher. Trying to get my iron up as well and it looks like selenium (see below) may also help with that.

25 OH Vitamin D 89 (50 - 200)

Too low.

What is the optimal level then? The lab states over 75 is sufficient, but is there a level that is optimal for thyroid health? I take calcifediol daily already.

Whole Blood Magnesium 33.6 (29 – 42)

No point in testing magnesium because the results aren’t reliable due to the way the body handles it. But if you’re going to supplement vit D, you need to also take magnesium because the two work together. No problem. It’s water soluble so excess – if there were any, which is doubtful – would just be excreted.

I take magnesium every day. I should get another red cell magnesium test at some point, the lab I had the other items tested at recently, does not offer this, unfortunately. I also take vit K, else the vit D can go into the arteries rather than into the bones. When I took too much magnesium, it was indeed excreted, as diarrhea, leaving me dehydrated and mineral / vitamin deficient. I've now found the best type of magnesium and best dose for me, fortunately.

Whole Blood Selenium 94.8 (85 – 200)

This is low, and could be one of the reasons your conversion is poor. Have you tried taking selenium?

I now take 1 Brazil nut per day and will reassess in 1 month time. I have MCAS so need to make any changes gradually or it will backfire on me.

Red cell folate 481 (340 - 1474.7)

Low.

You might benefit from a good B complex. That is to say one that contains methylfolate and methylcobalamin rather than folic acid and cyanocobalamin.

What is the optimal level for red cell folate please?

I was trying NDT (Erfa) for a short while (probably just over a week) and wasn’t feeling well. I had my bloods tested but this was while taking NDT:

TSH 0.75 (0.27 - 4.2)

FT4 12.4 (12 - 22)

FT3 4.6 (3.1 - 6.8)

This is when I added 50 mcg of Levo (Mercury Pharma) to my daily routine and when the bloating increased and the heartburn really took off.

Well, if I've understood correctly, you tested too soon, increased too soon and gave up too soon. Of course TSH and FT4 were going to be low because of the T3 in NDT. But you were under-medicated there. Instead of adding levo, you should have continued to increase the NDT by 1/4 grain every two weeks or longer.

I felt miserable while taking NDT. Felt better for a very short amount of time, then it went quickly downhill. I asked about it in the group and decided to go back to Levo and try to work on my T4 to T3 conversion. I’m not going to risk getting esophageal cancer from constant acid reflux by continuing to take NDT. I may try something like NDT or T3 again later, and then only when my T4 is optimal. It was not optimal when I tried NDT recently and I should’ve never been recommended it by my doctor at that time. With my T4 being suboptimal, it was not going to work for me, I just didn’t know that at the time.

[greygoose in reply to PinkCat2023]

I’d rather work on getting proper conversion from T4 to T3, if possible. Last time, my T4 went really low when I took NDT. Something is wrong there, so rather than trying to compensate for that by taking a medication similar to what made me feel so awful last time, I’ll try to get to the root and obtain better conversion first, to see if that helps.

That's all very laudable, but I've never heard of anyone actually managing to do that. There are so many reasons for poor conversion, the chances of your finding the reason for yours is pretty slim. It could just be due to low nutrients - including selenium - but it isn't always. It could just be down to having Hashi's, and there's nothing anyone can do about that. Or it could be genetic, etc. etc. etc.

Were your Brazil nuts grown in selenium-rich soils?

Not surprising your FT4 reduced when taking NDT. That's what T3 does. And it isn't always a problem, depends on the person. But synthetic T3 and T4 are different to the T4/3 in NDT because they're not bounc. In NDT they are bound, and that doesn't agree with some people - especially people with Hashi's. Certainly didn't agree with me! So, you can't really compare them.

What is the optimal level then? The lab states over 75 is sufficient, but is there a level that is optimal for thyroid health? I take calcifediol daily already.

The lab is talking about euthyroid people, not hypos (they don't know anything about hypos). And, in any case, sufficient isn't the same as optimal. When you're hypo you need it at least over 100 - possibly higher, given that range.

When I took too much magnesium, it was indeed excreted, as diarrhea, leaving me dehydrated and mineral / vitamin deficient.

So, I'm guessing that was magnesium citrate? There are other forms that don't do that.

What is the optimal level for red cell folate please?

I'm not sure but probably at least over mid-range - and remember that optimal for a hypo is usually higher than optimal for a euthyroid person. But look at the range, it's right down the bottom, only 12.43% through the range. Pretty certain that's not optimal.

I’m not going to risk getting esophageal cancer from constant acid reflux by continuing to take NDT.

Have you ever tested your stomach acid level? It's pretty likely to be low, and that is what causes acid reflux. The symptoms are the same as having high stomach acid. Try the burp test:

You drink half a glass (4 ounces) of cold water with a quarter teaspoon of baking soda, on an empty stomach. Then time how long it takes you to burp. If it takes longer than three to five minutes, the theory goes, you don't have enough stomach acid.

But, there's absolutely no reason why you should stay on NDT if you don't want to. You don't have to defend your decision. I couldn't tolerate it, either, for whatever reason, and I'm only well on T3 mono-therapy. We all have to find what's right for us.