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Thyroid UK
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thyroid hormones and beta blockers

I remember reading somewhere in the forum that beta blockers decrease T4 to T3 conversion. Does anyone know if they can also affect the way your body handles direct T3?

I was on Thiroyd from Thailand in the summer of 2012, felt really good on 5 grains daily, and this was confirmed by labs (above mid-range FT4 levels, FT3 levels at the top of range). A year later, I was put on beta blockers (Tenormin) along with blood pressure medication. Looking back, I realise I have not felt as good since. In February of this year, after almost three years on beta blockers, both my FTs were at the bottom of range on 5 grains of Thiroyd. I then realised my returning hypo symptoms coincided with the drop in my free Ts. I switched to Thyroid-S as some claim it's more potent, but I seem to require a minimum of 8 grains daily to function.

Has anyone else experienced this on beta blockers? If indeed they do decrease T4 to T3 conversion, I can understand that would be a problem for someone on T4 drugs only, but NDT no longer seems to be working the way it did...and it contains a lot of direct T3 which logically should not have anything to do with decreased T4 to T3 conversion. I read a post here recently claiming NDT no longer contains porcine thyroid, and that most people seemed to experience a change for the worse around the time there was a shortage of pigs (due to swine fever or something like that?) a few years ago. It is sometimes said that NDT pills are supposed to stink, but mine have no smell at all...and I have tried several brands: Armour, Erfa, Thiroyd, Thyroid-S...all smell free.

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A few years ago, I was prescribed the beta blocker Propranolol for a non-thyroid related condition. I tried to tell the medics involved that this medication was impacting my thyroid levels and hence my medication dose, but no-one seemed to believe me. I found a few papers relating to this, which I'm linking below for you in case they are helpful. There may be other papers of course.

Different variations of beta blocker may have different effects, so researching on the particular beta blocker that you are taking seems sensible.

Propranolol and thyroid hormone metabolism. ncbi.nlm.nih.gov/pubmed/168...

Three-compartmental analysis of effects of D-propranolol on thyroid hormone kinetics. ncbi.nlm.nih.gov/pubmed/338...

Propranolol has direct antithyroid activity: inhibition of iodide transport in cultured thyroid follicles. ncbi.nlm.nih.gov/pubmed/810...

D-propranolol and DL-propranolol both decrease conversion of L-thyroxine to L-triiodothyronine. ncbi.nlm.nih.gov/pmc/articl...


Very interesting, thank you so much! It does seem that some beta blockers have antithyroid activity that is not limited to T4 to T3 conversion...I'll try to find som info on atenolol which is the active ingredient in Tenormin.


Interesting information RedApple, i have been taking Propranolol for about 30 years for migraine prevention , i dont get migraines any more thank god, but have often wondered if they interfere with my thyroid meds, i think i will also have to research to find an alternative Beta Blocker.


Most beta blockers are fine except for propanalol and amiodarone. Propanalol is used to treat hyperthyroidism. Amiodarone contains tons of iodine and can have various thyroid disrupting effects.


I am on prop for severe anxiety which might partially explain my lowering t3 and high rt3, and high tsh results recently. What other one could i recommend my gp give me?


See my profile.

I was stuck on propranolol for about 18 years. Recently been able to stop after going gluten free and taking magnesium supplement. Now just dealing with residual low vitamin D.

You might find reading The Magnesium Miracle interesting - re how propranolol lowers magnesium and parathyroid levels.

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I have been gluten free since jan and still i have high antibodies. Your profile is what i am going through. Also take vit d and lits others. What mag do you take


I use natural calm magnesium (powder drink) available on Amazon and few other uk sites.

Started with small dose (1/4 teaspoon) just in evening and increased slowly. Bonus of making me feel calm and sleepy.

Really noticed to begin with, the same calm effect each time I took it. Now just feel more myself and don't notice any change when take it.

Taking 1/2 teaspoon after breakfast and lunch. Full teaspoon about 7pm. I take my Levo at bedtime (I gather it should be at least four hours away from magnesium)

Also was until recently alternating with Re-Mag - taking Re-Mag breakfast & lunch and Natural calm in evening.

Re-Mag is more expensive but did seem less prone to upsetting my tummy and doesn't perhaps seem to make me as sleepy. But it is currently out of stock anyway in Uk and I ran out. Now just using Natural Calm and seems fine.

Re-Mag, I have only found one UK supplier (Botanica Health). Re-Mag mentioned/recommended in The Magnesium Miracle. (I think author has something to do with its manufacture) Can buy direct from USA (a bit cheaper) but would be expensive if had to pay international postage and import tax

Might be coincidence, or to do with going gluten free as well, but my hair and skin are much better. Also my arms were like fat overblown sausage balloons (couldn't pinch skin) ...now seem to have much less mucin. Only downside, got my bat wings back!

Just got to get my legs walking better - but that I know is due to low vitamin D and is improving.


I had a vit d test a while back via my docs but have just ordered one online to do from home cus I am sick of not getting any help from my GP. My skin is really dry but I have been having so much going on for 8 months now including high daytime cortisol levels, especially first thing in the morning. I went hyper last autumn with really severe anxiety, panic, depression and now suicide thoughts. I have tried to get myself straight but am still struggling. Went with a private endo who ended up saying (after lots of tests) that I just need to get my stress levels down. He didn't even address my high antibodies. Just because I have depression and anxiety on my records from years ago he just thinks that has set everything off, which he could be right to a point, but I know there is much more going on. My T3 is now under range, I have high rt3, tsh has crept up, barely eat some days, lost 2st since last October.

I have a skype appointment with Dr Clark in the US on Wednesday and I am hoping he can guide me in the right direction. I am at a loss as to what to do now and am ready to leave this earth because I can't exist like this for much longer


Sorry to hear you are having such a tough time. I know how awful anxiety can be.

Personally I tried NDT and T3, but couldn't get on with either. Levo definitely isn't perfect, but for me it at least it seems the best option. Even Levo, I find needs very careful management, and constant steady dose. When I increased to 150mcg, TSH was only just below bottom of range, but T4 also went slightly above range - I felt terrible. Took nearly a year back on 125mcg before I began to feel better, it was very tough sticking with it.


what difference did you find in taking your Levo at bedtime from mornings?


A lot. Difficult to say how.

Discovered by accident, when I took Levo about 4am and then went back to sleep.

I suspect to some extent morning dosing was affected by me rarely waiting 30 mins before having cup of tea.


So does this mean that atenolol does not have the same negative effects on thyroid function?


I was taking a low dose (25 mg) of Atenolol for a few months while increasing Levothyroxine. There was little change in my TSH. Perhaps I should've taken them 12 hours apart?


I don't have any knowledge of atenolol but here is an abstrat on the topic ncbi.nlm.nih.gov/pubmed/?te... . I have taken sotalol in the past and found it OK. So maybe see if your doctor thinks sotalol would suit you.


Did you take the solatol for anxiety?


I have noticed that I needed to raise thyroid meds (NDT) after weaning off Medrol which I had been on for four years (diagnosed with adrenal fatigue in late 2011). I don't know if this is a sign my adrenal glands are still struggling to cope...however, I have felt quite all right since weaning off Medrol earlier this year, while taking adrenal cortex supplements and licorice root to support adrenal function. But I cannot exclude the possibility my adrenal function still has not optimised...and possibly never will. It seems not everyone recovers completely from adrenal fatigue. I realise now (which I never considered before going on Medrol) that prescription drugs like HC and Medrol will suppress adrenal function, and that the adrenal glands need some time to kick back in after you've weaned off steroids...unless they are actually dysfunctional, and not just tired.


This is interesting because I was recently put onto a calcium channel blocker called Diltiazem. It knocked my thyroid for six. I don't know what my actual readings were because I could not tolerate it long enough to get tested but after a couple of days of taking it, I felt like my thyroid was trying to claw it's way out of my throat. I added a quarter of a grain of NDT (because my last test showed I could afford to up my thyroid meds a little) and that helped but as soon as I tried to raise the CCB again (as instructed by doc) the same thing happened.

Google told me that CCBs are often given to hyper patients who cannot tolerate beta blockers.

I tried to talk to the consultant about this but got a very patronising lecture about how it could not possibly be the Dilitiazem that was causing my probs. He still changed my tablets though and the new CCB isn't causing the same problems.

Incidentally, I was prescribed a beta blocker when I first got ill last year and my doc mistakenly thought I had angina. Within 2 hours of taking the first one, I felt like I was dying! I've never had such a strong adverse reaction to anything.


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