Thyroid Peroxidase antibodies

[Mothebear]

Thyroid peroxidase is an enzyme which is produced in the thyroid gland and is important for converting T4 to the biologically active T3. If I produce antibodies to thyroid peroxidase I understand this indicates that the body's immune system is attacking the thyroid gland and impairing its function.

So, in layman’s terms does this mean, if I have higher levels of antibodies that I convert less of my T4 to T3 (or is that either too simplistic, or even wrong)?

I had many symptoms that resolved since taking T3 as well as T4, but I am wondering when/if I may need a higher dose of T3.

My peroxidase antibodies dropped initially when taking T4 and T3 (2022) but appear to be climbing again (still taking T4 and T3 in same amounts).

Any insights much appreciated.

[GlowCoach Administrator]

Thyroid Peroxidase antibodies don't mean anything to do with conversion. They signify that you have autoimmune thyroid disease/Hashimoto's disease.

Antibodies will fluctuate naturally throught the course of your life regardless of what you do although some say that eliminating gluten from their diet has reduced antibodies. Taking T4 and or T3 will not affect antibodies.

Higher levels of antibodies mean your thyroid has been attacked by your immune system more recently.

To assess your bodies ability to convert T4 to T3 you would have a genetic test looking at the DIO2 gene.

To assess if you need a higher dose of hormone you would do a blood test.

Recommended blood test protocol: Test at 9am (or as close as possible), fasting, last levo dose 24hrs before the blood draw, last T3 dose 8-12 hours before blood draw & no biotin containing supplements for 3-7 days (Biotin can interfere with thyroid blood results as it is used in the testing process)? Testing like this gives consistency in your results and will show stable blood levels of hormone and highest TSH which varies throughout the day. Taking Levo/T3 just prior to blood draw can show a falsly elevated result and your GP/Endo might change your dose incorrectly as a result.

[Mothebear in reply to GlowCoach]

Thank you Jaydee. I have done the Dio2 test and that underpinned my getting T3 prescribed. I also do my blood tests strictly as advocated on this site. My blood levels as recently tested by NHS and Medichecks are looking fine.

My question thus referred to the antibodies as possibly being a marker of a shift in the status of my thyroid and I take from your answer that they are not, so thanks again,

[helvella]

I think you are confusing Thyroid Peroxidase with the deiodinases (mainly D1 and D2).

The deiodinases exist throughout the body.

en.wikipedia.org/wiki/Iodot...

Thyroid Peroxidase enzymes do the original iodination of tyrosine within the thyroid.

en.wikipedia.org/wiki/Thyro...

[Mothebear in reply to helvella]

Thank you Helvella

I have tested positive on Dio2 and so have been prescribed T3. I conclude I just need to monitor my bloods regularly as any shift in T4/T3 needs will show there.

[V3ra in reply to Mothebear]

how did you get your Dio2 checked? Was that privately or by the nhs? I haven’t seen that test before so interested to know.

[RedApple in reply to V3ra]

NHS won't do the DI02 test. It's far too expensive! You can get it done privately. Some info on TUK website here thyroiduk.org/deiodinase-2-...

[V3ra in reply to RedApple]

Thanks, where did you get it done privately if you don't mind me asking?

[RedApple in reply to V3ra]

Sorry, I thought there was a link to the test on that page. You can get it here thyroiduk.org/help-and-supp...

[V3ra in reply to RedApple]

Much appreciated, I'll take a look

[Mothebear in reply to RedApple]

I have had it done thank you RedApple

[Mothebear in reply to V3ra]

Regenerus - £80 or so. Saliva test, results take a couple to three weeks. Fed back by their doctor £60 more, letter sent to GP - just your time. GP in my case had no idea all gene tests must be fed back by a medically trained individual and she had no idea what it was about. I just said print out the results for me and I will explain. Once I started explaining, her eyes glazed over and she said ‘you obviously know more about this than me’ I took the sheet and left, but it was the basis for my getting T3 prescribed by very angry endocrinologist! ‘This will cause a landslide’ she said, ‘I haven’t prescribed this for 7 years!

And we know why!!

[jendwall in reply to helvella]

I don't have a thyroid due to papillary cancer. Surgery was 10 years ago. No radiation.

Thoughts on still running TPO and TSI labs? The levels have never been raised since surgery. Just wondering if there is ever a chance that these antibodies can ever show up/increase down the road in my type of scenario.

I don't want to keep spending money on these tests if I don't need to. (I do still test Tg and Tg antibodies yearly which I know is important to keep monitoring for cancer recurrence.) Thank you!

[helvella in reply to jendwall]

I'd have thought absolutely no reason to do them.

Only the standard protocol for testing thyroglobulin post-thyroidectomy. (I'm being vague because it's not something I know much about.)

[jendwall in reply to helvella]

Just to clarify your first sentence, you don't know of a valid reason to continue running the TPO and TSI labs, correct? (Just wondering for knowledge sake, if it's ever possible for these antibodies to increase after a thyroidectomy.)

Also, I think it's interesting that Quest Diagnostics Lab here in the US gives the normal TSI lab value as <89. It seems like such a large window. Are all labs like that for TSI?

[helvella in reply to jendwall]

Correct. Even if you have antibodies, it's not clear they would be affecting anything.

Antibody ranges are odd. They can vary hugely.

Having a "normal" level of 100, then they might dilute and test again. If positive again, that would mean >200. But they wouldn't then go to 400, 800, etc. It really doesn't add any useful information.

(The units for some antibody tests are entirely arbitrary - sometimes they even put "AU/ml" meaning literally arbitrary units.)

[jendwall in reply to helvella]

Thanks for your insight!

[CoeliacMum1]

Thyroid peroxidase (TPO) does not have anything to do with conversion T4-T3 as far as I know.

I had higher levels of TPO with my T3 in better range last year… January this year my TPO levels were over hundred lower and my T3 was below range.

[Mothebear in reply to CoeliacMum1]

Hi

I find it interesting that everyone challenges my assertion of the link between T3 and T4, and I only quoted from the explanation Medicheck gives with the feedback on T3! 🤷‍♀️

[CoeliacMum1 in reply to Mothebear]

Just sharing my experience, and definitely no correlation in my case!

[helvella in reply to Mothebear]

Thanks for letting us know that.

I'm afraid they are flat out wrong. And I have just contacted them to point it out to them.

It could be careless copy and paste, ignorance, or numerous other things. But it ain't right!