Levothyroxine and cancer risk study

[ali2341]

Hi sorry to bring this negative info but i just saw a video where the doc is talking about the study , i wlll link study and video below. Just wanted everyones thoughts

pubmed.ncbi.nlm.nih.gov/337....

youtube.com/watch?v=toMxP52...(Not working as expected?)

[helvella Administrator Thyroid UK]

jimh111 has posted about such issues several times. Hopefully he will be available to respond.

You might care to click on his name and look through his profile.

[jimh111]

I've looked at the video, it is informative and well balanced. It seems that Dr Childs is only aware of this one study. There have been many and the major factor that promotes cancer in levothyroxine patients identified (T4 binding to the avB1 [alpha v beta 1] receptor).

Dr Childs guesses that patients on levothyroxine monotherapy may be more prone to cancer because they might be under-treated. In fact, it is the high levels of T4 that make them more susceptible to cancer. There is evidence T4 makes cancer more agressive, so although it increases the risk of cancer the mortality risk is higher.

My original post is here healthunlocked.com/thyroidu... . Note levothyroxine is not 'bad'. The risk comes from higher T4 levels nomatter where the T4 comes from (the thyroid, levothyroxine or NDT).

I did a follow-up post that looks at T4 and cardiac risk healthunlocked.com/thyroidu... .

In general, healthy people with a low normal fT4 live longer than people with a high normal fT4. My view is that when we treat hypothyroidism we should target fT4 to the lower part of the reference interval and use a little liothyronine to bring their fT3 up to normal. At present we are giving hypothyroid patients higher fT4 levels that are shortening their lives.

This is especially important in treated thyroid cancer patients where high doses of levothyroxine are use to suppressed TSH (to reduce the chance of thyroid cancer coming back). NICE are currently looking into thyroid cancer, if I get time I will submit some comments to them.

[StitchFairy in reply to jimh111]

There's a lot of sense in what you say. That it's high levels that are the risk, not the levo itself.

[helvella Administrator Thyroid UK in reply to jimh111]

My view is that when we treat hypothyroidism we should target fT4 to the lower part of the reference interval and use a little liothyronine to bring their fT3 up to normal.

Why would anyone think otherwise?

We can discuss exactly where fT4 should lie, and exact doses. But the principle that we need both seems unassailable.

Many areas of medicine see things slightly more comprehensively. In general, we produce tears which keep our eyes wet. But if we don't we likely need drops, not just an extra glass of water.

Breathing and metabolism produce carbon dioxide. But if there is not enough to keep the heart rate good, an anaesthetist will add a little to the oxygen during an operation. They don't insist that you exercise to make more carbon dioxide!

Subtleties abound in medicine. Why does this particular one seem to present such an insurmountable barrier?

[jimh111 in reply to helvella]

We have an added difficulty. It has long been believed that T3 would be more hazardous than T4. Indeed this was my instinctive feeling, we are bypassing the deiodinases which are a protective mechanism. Getting endocrinologists to let go of the anti-T3 mindset will be very difficult.

[ali2341 in reply to jimh111]

found this too you are right, high t4 levels are causing this

thyroid.org/wp-content/uplo...

[tinkerbell22 in reply to helvella]

So true, it drives me mad. This has helped me rethink my current way of doing things

[ali2341 in reply to jimh111]

This is scary im on t4 only , dont feel like taking it now

[tinkerbell22 in reply to ali2341]

I am T4-only too, as I'm really sensitive to T3 but it's making me think more about conversion of T4 to T3. I wouldn't need as high T4 to feel good if I could convert to T3 better?

[ali2341 in reply to tinkerbell22]

yes thats right but im on t4 only too, im going to take t3 now and less t4 to balance things out,

[jimh111 in reply to ali2341]

It's a relative risk the absolute risk is still smallish. I'm on combined L-T3/L-T4 therapy but if I was on levothyroxine monotherapy I would push my doctor to prescibe a little liothyronine (10 mcg with 30 mcg less levothyroxine?) so that I could get my fT4 below half-way. If your fT4 is not above average it should not matter much.

Please note I am a patient not a doctor and this is my view based on what I have researched.

[tinkerbell22 in reply to jimh111]

Does taking T3 affect your level of T4? I know taking T3 suppresses TSH as I've had this happen, but can't remember if it alters T4 as well?

[jimh111 in reply to tinkerbell22]

If you have functioning thyroid tissue and your TSH is not already very low then taking some T3 will lower your TSH causing your thyroid to secrete less T3 and T4. So, in these circumstances taking T3 will result in a lower T4. In general I would suggest taking a little T3 and reducing your levothyroxine dose on a 3:1 ration. e.g. 10 mcg L-T3 reduce L-T4 by about 30 mcg. This is because T3 is about 3x as potent as T4 when taken as a tablet.

[tinkerbell22 in reply to jimh111]

Thanks so much jimh111. So if one could take T3 while reducing T4 meds, they'd have a double whammy lowering of T4. Unfortunately I'm really sensitive to the stimulating side of T3, it makes my mind race really badly and I get hyperactive and then crash further. So I don't know if this regime is possible for me right now unless I can find a solution to my sensitivity.

However it got me wondering, could high T4 just be an issue if it's not converting properly into T3? So is high T4 like a waste product that's stuck in the body when it doesn't convert? So could just being a better converter solve this risk of higher than average T4? (When a person can't take T3 meds)

[jimh111 in reply to tinkerbell22]

When my fT4 was high, above the upper limit I found my response was erratic. It seemed that it would convert to T3 in spurts. If your fT4 is above midway I would lower it before introducing T3.

[tinkerbell22 in reply to jimh111]

Wow thanks so much for this jimh111, I had no idea. I must've missed these conversations before. Really informative

[tinkerbell22]

Thanks for posting this as it's triggered really informative responses!

[SarahJane1471]

If this is absolutely true can we use this research to press our GP s to prescribe T3?

[ali2341 in reply to SarahJane1471]

i dont think most of them will have a damn, im going to order t3 and do it my self

[SarahJane1471 in reply to ali2341]

Maybe get FT4 up to a good level first and see where FT3 is before ordering T3

[tinkerbell22]

Thing is ali2341 I've made big leaps in my thyroid therapy before and it's a Really Really bad idea. I've increased by too much too quickly, but I've also come off a high dose of T4 suddenly, twice (becoz of a heart pain reaction once, and second time becoz of a medicine shortage). Both times I was ok coming off T4 for a short time but by 3 months I was so bad I couldn't move. Stopping T4 is really dangerous, it can cause a person to go into a coma, I've read here. And some people go downhill fast with suddenly cutting T4. So despite the fear of reading these articles, gentle and slow adjustments need to be made so as not to shock your body

[ali2341 in reply to tinkerbell22]

ye good idea

[SarahJane1471]

I think I’m now nervous of T4 mono therapy …….. but I have no other choice. I cant afford to buy T3 or NDT so I’m stuck with NHS prescribing. 🤷‍♀️

[SarahJane1471]

jimh111 helvella et al can I ask how many studies have there been re the cancer risk and T4 mono therapy?

[jimh111 in reply to SarahJane1471]

The studies I know of are mentioned in this link healthunlocked.com/thyroidu... which I gave in my earlier reply. I searched PubMed for 'thyroxine avB3' if I remember so it may not pick up some studies. I don't think there have been studies specifically looking at levothyroxine monotherapy and cancer, most relevant ones looked at thyroxine and cancer. Of course levothyroxine monotherapy generally results in higher T4 levels.

[SarahJane1471 in reply to jimh111]

Thank you 😊

[ali2341 in reply to jimh111]

hi i am doing research in to your posts and its clear that t4 mono is linked to cancer, and i have decided i will take t3 and t4 combo, i have attached my results from over 1 year of t4 at 100mcg , this was few weeks ago and doc has increased my t4 to 125 mcg now , i want to try and lower my t4 and increase t3 by taking 100mcg of t4 and 12,5 mcg of t3, do you think this will lower my t4 and even now is it in ok range not to high ?

s

[jimh111]

It is T4 that is associated with cancer but of course levothyroxine monotherapy usually results in higher T4 levels. The studies show that T4 in the lower part of its reference interval is associated with better outcomes than higher levels. Your fT4 was average. You don't say whether your doctor increased your dose because you had symptoms or because of your TSH.

Assuming you had symptoms your proposal seems OK although you might do OK on 6.25 mcg but I don't know whether you could split this into two doses. I would aim to keep your fT4 a touch lower and keep to the lowest dose that resolves your symptoms. Remember I'm out a doctor.

[ali2341 in reply to jimh111]

I told doc i was still having symptoms , hard to lose weight, low energy and depression, so he increased to 125 mcg but this test was done private few days before, dont think that will bring my tsh from 3.7 to 1 or under, But will try combo route, also do you know a reliable source to get t3 in uk ? if you or anyone can dm that would be helpful thanks.

[jimh111 in reply to ali2341]

If you can get a private prescription for Thybon Henning you can obtain it from one of the pharmacies on this list thyroiduk.org/if-you-are-hy... . I've never bought it without a prescription so perhaps someone else can advise you by private message.

[ali2341 in reply to jimh111]

hi sorry to keep on going on about this topic but i found a site where they are discussing the study

paulrobinsonthyroid.com/new...

frontiersin.org/articles/10...

[jimh111 in reply to ali2341]

I've read Paul's article, I think the major factor is T4 action on the integrin αvβ3 receptor. I have also seen Hercbergs' review. There are many papers on this topic, I detail some of them here ibshypo.com/index.php/thyro... .

[ali2341 in reply to jimh111]

Hi just wanted some advise please, i have some t3 25mg and will cut to 4 pieces to take 6.25 mcg in morning along with 100mcg of levo, is it ok to dose t3 once a day or will it be a waste ?

[Miffie in reply to ali2341]

With FT4 at 49% and FT3 at 54.34 you have no conversion issues. This being the case you do not need to add T3 for thyroid health. I appreciate there is some limited evidence of high T4 and cancer but your T4 is just under half way. I wouldn’t add T3 with those results, but that is personal choice. I know I need both fT4 & 3 in a good place.

Hopefully you won’t have side effects from adding T3.

The other thought is you will need to explain all this to the GP after next blood tests which will probably show a decrease in fT4 and TSH. More than likely they will suggest lowering levo dose. That can be tricky if they don’t accept self sourcing hormones.

I am fortunate that the endo was happy to tell my GP he has no problem with my adding ndt to levo.

Take care and good luck.

[ali2341 in reply to Miffie]

yes its true that i am converting good but because of the cancer study i seen this last week it makes me really paranoid to take more 125mcg t4 , i just want to make my t3 a bit higher so i can lose weight and maybe improve mood. im hoping the little extra t3 can help

[jimh111 in reply to ali2341]

You can take it once daily, especially as it is a small amount. It probably isn’t enough to make much difference to symptoms.