Should I be concerned about low TSH?

[Coachv]

Just got my results back from Blue Horizon self- test and doc's comment is that the TSH is below the reference range so too low.

THYROID STIMULATING HORMONE * 0.15 (mIU/L 0.27 - 4.2)

FREE THYROXINE 18.4 (pmol/l 12.0 - 22.0

)

FREE T3 4.8 (pmol/L 3.1 - 6.8)

I take approx 90 mg T4 daily plus 5mg T3. Since the TSH is not actually suppressed and the other results are reasonably within range, should I be concerned? I am cautious as I had atrial fibrillation and osteopenia, both of which seem to be linked to suppressed TSH. Have not had AF since reducing my thyroid replacement doses.

My last TSH test via GP in December 2018 was

TSH 0.2 (mU/L 0.2 - 4.5)

GP has not raised any concerns over this.

Thanks.

[SeasideSusie Remembering]

I think you'll find your taking mcg (micrograms) not mg (milligrams)

How do you feel?

Those results look fine, FT4 and FT3 both in range.

If you don't feel 100% then FT3 is on the lowish side, you could trial 10mcg daily rather than 5mcg.

How do you get 90mcg Levo?

[Coachv in reply to SeasideSusie]

Thanks

Oops yes mcg.

I take T4 100 mcg four times a week and 75 mcg three times a week, which averages out at 89 mcg a day.

I did try taking 10mcg T3 and less T4, as advised by an endocrinologist, but this suppressed my TSH and also free T4 level was right down.

I read quite a lot of research which suggests that suppressed TSH is linked to heart arrhythmia, and reduced bone density, so am very cautious about this, as I am in my 60s. The current dosage seems okay, although ideally I would like to take 10 mcg of T3, which I took for many years until I developed atrial fibrillation.

It would be great if this whole issue was much better researched, as I feel I am experimenting on myself.

[SeasideSusie Remembering in reply to Coachv]

I did try taking 10mcg T3 and less T4, as advised by an endocrinologist, but this suppressed my TSH and also free T4 level was right down.

That's generally what happens when adding T3 into the mix. It amazes me that doctors who prescribe T3 don't seem to know the effect it can have on test results.

[SlowDragon Administrator in reply to Coachv]

Did you try the 10mcg dose as 2 x 5mcg?

Not sure you would need to reduce Levo either

How are your vitamin levels?

[Coachv in reply to SlowDragon]

Yes I divided the dose. The endo prescribed reduced T4 with 10 mcg T3.I have not had vitamins checked recently but take some supplements.

Thanks

[SlowDragon Administrator in reply to Coachv]

So you need to test vitamin D, folate, ferritin and B12

Low vitamins can lower TSH

Though it's extremely common for TSH to be suppressed on even tiny dose of T3

Most important are FT3 and FT4 levels

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and fasting. Do not take Levothyroxine dose in the 24 hours prior to test, delay and take immediately after blood draw. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

on T3, make sure to take last dose 8-12 hours prior to test

Is this how you do your tests?

Do you have Hashimoto's? Autoimmune thyroid disease diagnosed by high thyroid antibodies?

If so are you on strictly gluten free diet

Low fT3 (common on T4 mono therapy) may linked to osteoporosis and af

tiredthyroid.com/blog/2012/...

ncbi.nlm.nih.gov/pubmed/175...

See point 3.3

academic.oup.com/ejcts/arti...

ncbi.nlm.nih.gov/pubmed/164...

stopthethyroidmadness.com/a...