Can levothyroxine cause hypothyroidism? - Thyroid UK

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Can levothyroxine cause hypothyroidism?

nara8 profile image
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This happened about 25 years ago: I had hashimoto's and a large goiter, but tsh and thyroid hormones were normal. Before starting levo I had some symptoms: dry,fine hair, some cognitive issues... but I felt almost healthy and was active 17 hours a day). When levo was prescribed, I felt very cold and slept 12 hours a day, had mood swings, anxiety, depression...

But these are symptoms of overt hypothyroidism, aren't day?

Does treating goiter with levo make the thyroid smaller and underactive, or my symptoms were just because my body was functioning on synthetic t4? My weight was 40 kilos then and the doctor( a surgeon) prescribed 100mcg a day. I developed subclinical hyopothyroidism and then overt hypothyroidism about 6 or 7 years later.

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SlowDragon profile image
SlowDragonAdministrator

Taking levothyroxine will result in shutting your own thyroid down

It’s essential to be on correct dose levothyroxine

Often needs fine tuning

Also essential to maintain GOOD vitamin D, folate, ferritin and B12 to enable good conversion of Ft4 (levothyroxine) to Ft3 (active hormone)

Many thyroid patients struggle to convert Ft4 to Ft3 adequately, especially with Hashimoto’s

Many hashimoto’s patients also find it beneficial or essential to be strictly gluten free and/or dairy free

Just testing TSH and Ft4, all that’s typically done, is completely inadequate

For full Thyroid evaluation you need TSH, FT4 and FT3 tested

Very important to test vitamin D, folate, ferritin and B12 at least once year minimum

About 90% of primary hypothyroidism is autoimmune thyroid disease, usually diagnosed by high thyroid antibodies

Autoimmune thyroid disease with goitre is Hashimoto’s

Autoimmune thyroid disease without goitre is Ord’s thyroiditis.

Both are autoimmune and generally called Hashimoto’s.

Low vitamin levels are extremely common when hypothyroid, especially with autoimmune thyroid disease

In U.K. medics hardly ever refer to autoimmune thyroid disease as Hashimoto’s (or Ord’s thyroiditis)

Recommended that all thyroid blood tests early morning, ideally just before 9am, only drink water between waking and test and last dose levothyroxine 24 hours before test

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip)

Private tests are available as NHS currently rarely tests Ft3 or all relevant vitamins

Testing options and includes money off codes for private testing

thyroiduk.org/testing/

Medichecks Thyroid plus antibodies and vitamins

medichecks.com/products/adv...

Blue Horizon Thyroid Premium Gold includes antibodies, cortisol and vitamins

bluehorizonbloodtests.co.uk...

Only do private testing early Monday or Tuesday morning.

Link about thyroid blood tests

thyroiduk.org/testing/thyro...

Link about Hashimoto’s

thyroiduk.org/hypothyroid-b...

Symptoms of hypothyroidism

thyroiduk.org/signs-and-sym...

Tips on how to do DIY finger prick test

support.medichecks.com/hc/e...

Medichecks and BH also offer private blood draw at clinic near you, or private nurse to your own home…..for an extra fee

nara8 profile image
nara8 in reply toSlowDragon

Thank you Slowdragon. Do you know whether endocrinologists treat goiter without hypothyroidism? Will the thyroid get smaller and underactive?

greygoose profile image
greygoose

But these are symptoms of overt hypothyroidism, aren't day?

Indeed they are. But it's not unusual for symptoms to get worse when starting thyroid hormone replacement - or even for new symptoms to appear. Remember, you had probably been hypo for quite while at the point of diagnosis for the goitre to have formed and be noticable.

but tsh and thyroid hormones were normal

Hmmm... Debatable. For a start, there's no such thing as 'normal' where thyroid is concerned. Because we all have different needs. And, when a doctor says 'normal', all he means is that the results are somewhere within the so-called 'normal' range. But, consider how wide these ranges are - they can't be 'normal' all the way through - not for you, anyway, although maybe for someone else. Do you remember what the results and ranges were?

Does treating goiter with levo make the thyroid smaller and underactive

Well, you weren't taking the levo treat the goitre. You were taking it because you had Hashi's, and even if your numbers had been 'normal' at the time, you would have eventually become hypo. But, I suspect that your numbers were abnormal enough for someone to have recognised that you needed thyroid hormone replacement - which is what levo is. It's the thyroid hormone T4.

So, although it might have shrunk your goitre - which is a bonus - it certainly didn't make it under-active - it was already that. And, as SlowDragon says, by lowering the TSH, it would have put your thyroid to sleep, so to speak. Stop the levo and the thyroid will go back to making whatever hormone it was making before.

or my symptoms were just because my body was functioning on synthetic t4?

Synthetic or natural (NDT) it's all the same. It's T4 and it's molecularly identical to the T4 your thyroid would make naturally if it could. OK, so levo doesn't suit everyone, but that's usualy down to the fillers in the tablet. But I doubt it would cause the symptoms you speak of.

I developed subclinical hyopothyroidism and then overt hypothyroidism about 6 or 7 years later.

Pretty certain you already had subclinical hypo before. But how did they know it became overt (we're just talking about numbers, here)? Did they stop the levo at some point?

nara8 profile image
nara8 in reply togreygoose

Thank you for your reply.

I know I have overt hypothyroidism because when I didn't take levo for 2 months my tsh was 77. T4 was low too.

greygoose profile image
greygoose in reply tonara8

OK, but that's due to the Hashi's, not the levo. :) Hashi's slowly and deliberately destroys your thyroid.

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