oestrogen inhibitors & thyroid medication

[The Wink]

Hi - have just joined the forum after researching possible interreaction between carbimazole and anastrazole. I am hyper, diagnosed in 2017 and was stable on carbimazole 5mg or 10mg on alternate days. BC diagnosis 2 years ago and taken anastrozole since Jan '21. Since then I've put on 12lbs and have night sweats, insomnia and too much energy for a 71 yr old! GP has been doing more frequent thyroid tests as TSH has been dropping. It is now low and my carbimazole has been increased to 10mg daily with a test after 6 weeks. One week in I am feeling much more normal. It makes sense to me that a new endocrine treatment might affect thyroid treatment and that weight gain could lead to under-treatment of thyroid. I'll post next blood test result 🤞 So helpful to read your stories - thank you 🎀

[isangwan]

I have been on desiccated thyroid for a long time without any issue but it is not available in US anymore.

would appreciate any information as to where in this world we can get it. May be UK or any other country.

I tried taking Levothyroxine, it has wheat flour in it, switched to Tirosint that has corn flour( better for me since I am gluten sensitive).  Ever since I started taking Tirosint andTamoxifen, my Reverse T3 has gone up. I wish I could find desiccated thyroid someplace.

[green dragonfly]

Hi Michele

I realise your initial post was over 6 years ago, but i just want to say thanks for posting.  I have been reading through all the comments which has really helped me this morning.  

I have been taking levothyroxine for 11 year, and, for the last 5 years approximately i have suffered with salivary gland pain (when drinking fruity drinks) and a dry mouth with difficulty swallowing - causing post nasal drip at night and a cough in the mornings.  

i was diagnosed with BC in september and had a lumpectomy, started taking anastrozole 1 month ago and have started my radiotherapy this week.  

I have finally (through talking to dentist) seen a specialist about dry mouth and 2 weeks ago was diagnosed with sjogrens syndrome.  Another autoimmune issue to add to hypothyroidism and Coeliac disease.

My dry mouth has got much worse and i was associating it with the Sjogrens, but upon reading all these comment realise it could be a clash between - levothyroxine and anastrozole.

will definitley get this checkout out in the new year once my radiotherapy is finished.

thanks again,  and it would be interesting to hear how everyone is doing after years of treatment

[pinkpink]

Sorry forgot to mention that my mom had a thyroidectomy and her thyroxine levels had always been okay until she started on letrozol.

Many thanks 🙂

[pinkpink]

Hello guys,

my mom was first diagnosed with breast cancer almost 5 years ago and about 7 months ago we found out that the cancer had come back and had spread to her liver. She is taking Zadolex, Ibrance and Letrozol.

At the beginning everything was fine but around two months ago she started feeling really badly every now and then. Every couple of weeks she had three days with strong headaches and vomits.

We went to the doctor many times but they did not find anything. We then finally found out that my mom had high blood pressure (which we thought it was a side effect of letrozol) and started taking medication to control it.

Even though she took this medication, she kept having these days in which she had headaches and vomits and her blood pressure would increase very quickly and keep going up and down the whole day. At that point we did not know what to do, until it occurred to us that they had not checked her thyroxine levels since she was first diagnosed with metastasic breast cancer, so we went again to the doctor to have that checked. And surprise, surprise the thyroxine levels were too high. So she stopped taking thyroxine for a few days and now she has started with a lower dosis.

We have seen that some of you had similar problems, did you guys also have a few days every now and then with vomits and headaches and irregular but high blood pressure? If so, did it completely go away once your thyroxine levels were regulated? 

Thank you in advance

[Marla13]

Hi Dabi,

I'm sorry to hear about your overactive thyroid. It is really important that your GP checks it regularly, especially if they haven't put you on any medication-have they explained why they haven't prescribed anything to you? 

I'm not entirely sure that I understand the connection between Letrozole and Thyroid problems but what I do know is that I have lost weight (intentionally) and it seems my symptoms were due to having too much thyroxine in my body, so now I need less of my thyroid medication (as well as my blood pressure medication). Weight loss means a review of meds because we can be "over treated". But it sounds like your weight loss was down to the overactive thyroid. I would just suggest you ask your GP to keep a close eye on it....which it sounds like they are doing.

Sending you hugs...

xxx 

[Dabi]

Hello Marla

I was treated for Stage 2 breast cancer and had radiation in September 2017. After one year of taking  Letrozole I started to lose weight. I was finally diagnosed with an overactive thyroid early this year. The doctor has not prescribed anything for iyet....said will keep an eye on it. I have already lost over 12 pounds. I have also lost a lot of hair. 

[Marla13]

Hi Gilly,

I thought I'd contribute to this discussion and reply to your message in particular-I had radioactive iodine for an overactive thyroid in 2010. Since 2010 I've been on Levothyroxine and my test results have always been in the normal range, however, I've been on Letrozole since October, had my 1st thyroid function blood test since starting Letrozole and my thyroid tests came back as over active. I am going away for 2 weeks this Wed. so can't repeat the blood tests till I returnm, but my GP said that before she lowers my Thyroxine, she wants to see if the repeat blood tests come back the same-she said sometimes a one-off blood test could be amiss. 

All this to say that I, too, feel the palpitations again and noticed that last night in bed I was aware of the palpitations all night.  I've had 4 hours of sleep. Surely the poor sleep cannot be good for the breast cancer or my general health. 

xxxx

[BlueMonday]

Thanks Belford Belle for the reply, I used to take my tablet first thing in the morning and everything was fine now I have to take the Bisphosphonate so can’t take it then any more 😕 hopefully my GP will tell me what to do x

[Bedford belle]

Hi all - I've been taking Levothyroxine for underactive thyroid since i was 20 and when i raised the likely side effects of thyroxine and tamoxifen with the onc he advised me to have regular blood tests as the tamoxifen can inhibit the absorbtion of thyroxine (apparently oestrogen is important in the process). So i wasn't suprised that after 6 months of tamoxifen my thyroxine dose was increased. I've slightly altered my morning pill taking routine to ensure that the first pill of the day is the thyroxine on an empty stomach and with water and try not to eat for another hour. The last pill of the morning (before rushing out of the door) is the tamoxifen - so far (2 years in!) I've only forgotten a handful of times so have a stash in my desk drawer.

The most recent blood test showed that my thyroid levels are satisfactory using this approach but i'm keeping an eye out for signs of becomming underactive again...

[BlueMonday]

Thanks for the reply yes that sounds like a good plan, I also take supplements so lots of tablets , yes life was much easier before BC

[Ruthiesings]

I'm taking both anastrozole and levothyroxine.  Initially I took the anastrozole last thing at night and the levothyroxine first thing, half an hour before breakfast.  I wasn't sure if the anastrozole was disturbing my sleep (not good at the best of times) so swapped to taking levothyroxine before bed (I find it easier not to eat after 8pm) and the anastrozole in the morning.  I've now been prescribed alendronic acid so have 'tweaked' the times yet again!  Will take the alendronic acid before breakfast (starting tomorrow!) and anastrozle with my breakfast as it's the only tablet that says you can take with food. All these tablets and when to take them is a nightmare.  Things were so much simpler before BC...

[BlueMonday]

Is anyone taking anastrozole and Levothyroxine (for an under active thyroid) at the same time , just wonder when was the best time to take the drug?I am also taking isonic acid which I take first thing in the morning and nothing to eat after that. Thanks😊

[Susieone]

Hi all
I've been reading msg in this thread, I have hyperthyroidism and been on carbimazole since Xmas. Started on 20mg now i take 5mg once a day.
I have been on letrozole for 3 weeks and have my radiotherapy planning Oct 2nd.
I am having lots of muscle and joint pains these have Increased since taking letrozole as I was managing the pain on carb.
Off to docs Monday will get bloods done as I don't see Endo for another month and would like to see if there's any changes.
I'm taking 2 painkillers at night Naproxen using muscle rub cream for now seems to help.

[GillyB4]

I'm interested in your experience of Letrazole and hyperthyroidism.  I had hyperthyroidism nearly 20 years ago, but it was successfully treated with a combination of carbimazole (to turn the thyroid off) and thyroxin (to replace the thyroid's activity) and I've been off all medication for it for 16 years, with no problem. 

I started taking Letrazole after breast cancer about four months ago, and apart from a few late hot flushes (I'm in my 60s!) have had no problem, but realised yesterday that I'm getting symptoms of hyperthyroidism again (dry mouth and palpitations).  I've booked a Thyroid Function Test, but am wondering what connection there might be, or if it is likely to be just coincidence!

[Boobyprize]

Hello Wavylocks

did u get sorted with dessicated thyroid?

im having ame terrible issues awful foot, hand, bone pain, exhaustion, weight gain despite healthy eating et..

GP says my thyroid bloods are in normal range but I know I'm hypo again !

just after some ideas / suggestions of who to ask for help...

Dulcie xx

[silverfox]

Hi folks. Just found this forem after I Googled Letrozole and NDT! So already a member of Thyroid Uk. Started on Letrozole in October and take that before bed and all my NDT in the morning. Found it rough to start with butvthinfs have settled down a bit since. Don't know what my score is, they didn't tell me divtgsts on my list to ask! Didn't have to have Chemo but did have radio therapy so. Even interesting reading your experiences. My thyroid state I think is pretty good and I take shedloads of supplements! So no real questions at the moment but just wanted to say hello!

[waveylocks]

Hi Michelle,

so sorry to hear about what has happened & how poorly you are feeling. The most common thing that happens is that people are under treated for hypothyroidism ... This causes palpitations & fatigue. No doubt you've discovered that you ft4 needs to be near the top of the range. The trouble with levothyroxine is that it is a synthetic hormone & t4 is the storage form so the body has to convert it to t3. Not everyone does this well so you end up with ongoing symptoms.. Levothyroxine does not work for everyone -certainly did not for me so the NDT I'm on has all the thyroid hormones in it. 

Ive got to say that since I've been on Letrozole it has NOT affected my uptake of thyroid hormone. Sine the other treatments have stopped I've been able to lower my dose back down. Been on Letrozole for a year now. Am starting to get some hot flushes at night though....

Do get your vit D level checked via blood test -GP can do it. You need to be around 80 at least. Low vit D causes bone pain, fatigue and un refreshed sleep. I felt awful and so tired could barely walk when mine was very low at 3, a few years back (prior to my cancer diagnosis).  So worth checking. 

Having said all of that my heart does funny little races -am under a cardiologist as apparently the Herceptin caused some damage. So on BP & beta blocker tablets. I feel better on the tablets -felt very tired and weak before.....lol

So there's a fair few factors that could be causing symptoms which are worth checking out before accepting it's the Letrozole. 

Ihope this helps....and hoping you find a way to ease your symptoms...

hugs xxx 

[Janey T]

I have been reading this thread with great interest! It seems I have just tolerated a lit during the past 5 years blamed myself for being tired, tried to carry on through aches and pains, and not made any links with my meds and neither have the doctors! FUMING

I have been on Levothyroxine since 2009 (other than gaps during radioactive iodine treatment) following diagnosis of thyroid cancer and complete thyroid removal. Breast cancer diagnosis end of 2010 Her2+DCIS so had surgery (lumpectomy, chemo, radiotherapy, herceptin, and hormone therapy) due to finish taking exemestane end if this month. I have had joint pains like you wouldn't believe, some days I can barely walk upstairs and I just didn't even think about the tablets, also soooo tired so often and just felt guilty!

[waveylocks]

Sorry Jennifed for some reason I don't get prompted that's someone replied to this thread. I'm afraid I don't know anything about hyperthyroidism and the inhibitors. Howeever if Having no Estrogen in the body is linked to a problem with uptake of thyroid hormone into the system this should benefit you? 

I uave had had to increase my thyroid meds yet again - I know it's colder so likely to need a tweak but even so. Since doing the latest tweak my high blood pressure has dropped and I have more energy once more 😊😊

I've also put a stone on since starting Letrozole 7 months ago so have started a low carb food plan. Hope it does the trick!! 

[Jennifed]

Hi ladies I've been reading your posts with interest and hope you don't mind me joining.   I am hyperthyroid and take 5 mg of carbimazole every day.  Neither the surgeon or tha oncologist were concerned by possible conflicts between the two kind of medication.  I had palpitations for the first time the other night but that might just be nerves from my first radiotheraphy treatment.  Does anyone else have experience of hyperthyroidism and hormone inhibitors? Jennifer

[waveylocks]

Hi Michelle,

Sorry for the later reply -have only just picked up your post. Lol.. I've just had to raise my thyroid meds as my Ft4 had fallen significantly, and some hypothyroid symptoms had started to creep back in.  So am grateful i was given the heads up on this as it is rare for me to raise my dose in the middle of a warm summer!!  

re NDT -you can get it on the NHS but you will have to find a GP who is sympathetic and willing to consider it -normally they will want to see if the standard treatment works well first.  I did have to buy my NDT privately for a couple of years to show that it was the most effective treatment for me. Am glad you have found Thyroid UK -it is a great resource and people on their are very knowledgeable and helpful.  

The Aldred Score is the test they use to see to what degree you are estrogen positive -the scale goes up to 8 -8 being the strongest estrogen positive you can be on this test.  I was an 8 so taking the Letrozole was no brainer for me. 

just as an aside -might be worth getting your vit D levels checked as low levels of that can make you very tired and achey -I could barely walk when mine were very low -I would sleep well but would wake up feeling exhausted.  Just a thought.  I know the Estrogen blocker can cause these symptoms too...

Hope your feeling better.  xx

[Seashell60]

Hi Lucy12 and Waveylocks, Thanks both of you for helping me with helpful info. My Levo has been raised from 75 to 100mcg daily, but as I have been taken off Anastrozole until I see the Breast Surgeon I don't know what happens next in August when my appt is.

Lucy, I get the same s/e too, the exhaustion takes over and it's an effort to do things especially when everything hurts! As for the irregular heartbeats, they're still there. And the weight gain! You mentioned STTM book, my local library managed to buy in a copy and I find it interesting. 

Waveylocks, I keep seeing NDT, mentioned in various forums, not all doctors will prescribe it will they? If it's pricey I doubt I will be so lucky. It was never mentioned to me about the possible link between thyroid meds and AI's, I found this out from talking to one of the Admin team on Thyroid UK on the Health Unlocked website. They gave me all the help I needed to get something done. My Thyroid Antibodies came back borderline to high, so when they're done next week I will know if it could be autoimmune.

I notice you both mention Allred score, what's that? I know I'm oestrogen receptive, but don't know any numbers.

Hope you are both keeping well. Cheers, Michele 💖

[waveylocks]

Hi Seashell, I was warned that being on Letrozole that I am likely to have to increase my thyroid meds -this is because estrogen helps with uptake of thyroid hormones.....given the aim is to zero the estrogen then this could pose an issue. So far have been ok but only been on Letrozole for three months. Has your thyroid condition being confirmed as autoimmune realated? If so keeping to a gluten free diest can help to lower the autoimmune response.

[Seashell60]

Well, I finally got some answers from the Breast Surgeon. He's taken me off Anastrozole and increased my Thyroxine until I see him in August. 3weeks yesterday and I have noticed changes in my heart and the painful joints. If he says to restart it I don't know what to do. The only other choices are change to another inhibitor or stop altogether. ????

[Seashell60]

Hi Lucy, I was checking different websites for Stop the Thyroid Madness, but they were quite expensive and the ones I saw were from the U.S. So I asked my local library to try and order it in, if they do it's only a 75p charge, if it's helpful I don't mind. I am waiting for the rest of my Thyroid results to see whether I am autoimmune, then my Thyroid can be altered. Otherwise, my GP said if the Anastrozole is causing my Thyroid to play up, she thinks the Oncs wouldn't be happy for me to stop it. But surely I have read some people have taken a Break from their breast cancer hormones to see if their symptoms lessen. I will try anything for a respite from it all.

Cheers, Michele x

[waveylocks]

Hi Lu,
Have you joined the forum ThyroidUk on Healthinlock re the dessicated thyroid extract? You'll find lots of helpful support on there. W
Stop the Madness is a good book 😊 I've been on a dessicated thyroid extract for 10years now -my GP prescribes it under the advice of a specialsit that I see. Welcome to pm if you want. Xx

[lucy12]

Hi Waveylocks

I've been reading lots about desiccated thyroid and it sounds like it is definitely worth a try - just a bit of a scary step going against a GP's advice so not having that safety net of knowledge (or useless knowledge as the case may be!) up the road.

I've ordered a book called Stop The Thyroid Madness and am hoping this will give me the confidence to take the plunge. It's good to hear you are doing well on it!

I was also 8/8 for oestrogen and progesterone so not an option to come off of tamoxifen.

Lu xx

[waveylocks]

Not yet on Letrozole but due to start it this forth coming week. I have had an underactive thyroid for over 10 years now and am on a dessicated thyroid as levothyroxine only partly sorted me. Am dreading starting the Letrozole as have heard so many problems associated with it but am very strongly Oestrogen positive (Allred Score of 😎 so know I must take it. 5 years they have told me. So really interested to hear from you all. Xx

[lucy12]

I have been on thyroxine for 16 years - currently on 225mcg a day. I've been on tamoxifen for 18 months and am struggling so much with side effects. I can happily sleep for 15 hours a day and still feel exhausted, have put on two stone, get palpitaions (I assumed due to the weight gain) and can hardly move some days with joint pain.

I had never considered there may be connection with the thyroxine. Thank you for the info, will join that group too!

xx

[chascat]

Hi Michele, I'm on I've been in Levothyroxine for 10 years (100 - 150 mg) and Tamoxifen for nearly 3, I have to say I've never had any side effects from my thyroid medication and very few from Tamoxifen but interested to hear of a facebook group. Sorry you're having such a tough time x

[Seashell60]

Hi, I am currently on the 5 years of Anastrozole, which started in September 2013. I had been diagnosed with an Underactive Thyroid 5 years previous and taking Levothyroxine, the synthetic thyroid hormone. Ever since I began taking the both hormones together, I have been on a horrendous journey of severe side effects, which I discovered today are the same in both these hormone drugs. So it feels like I am getting 100 times the side effects all at once! Because the Anastrozole inhibits the production of oestrogen, and the synthetic thyroxine replaces the Thyroid Hormone over again, my body is fighting a losing battle. The worst side effects (most of the side effects from both drugs are the same so you can see why I am struggling!), are irregular and ectopic heartbeats (I had every heart test going and my heart itself is fine), crippling joint, muscle and joint pain, brain fog, fatigue, dry skin and hair, the list goes on! I joined the Thyroid UK forum on FB and it is an invaluable source of information, and I have finally been chatting to others who are in the same situation with having Breast Cancer treatment alongside Thyroid treatment. Does anyone else identify with this and if so, what happened for you? Cheers, Michele. Xxx. 😁😁