Hi all, have been lurking and reading your valuable posts and replies. Thank you for being such an informative community.
Tl;dr - I've just moved to block and replace, am on day 2 of the medication. It's utterly wiped me out and I want to check if that's normal. I'd be interested in others' experiences of B&R.
Blood tests:
Nov 24:
- TRAb 16.8 iu/L (range 0-2.1 U)
- T4 90 (range 9-28)
- lost my note of the numbers but TSH was low and T3 high
Dec 24:
- T4 39
April 25:
- T4 6
Background and more info:
Diagnosed with Graves November 2024, symptoms of hyperthyroidism since the summer which GP dismissed as anxiety and gave me propanolol for. Looking back I think I may have had flare ups before and been dismissed. I had high levels and from August 2025 was experiencing unbearable tremors, disrupted sleep and anxiety alongside what my Endo described as a "full house of hyperthyroid symptoms". I lost a third of my body weight, but was engaging in some disordered eating.
On 20mg carbimazole a day from December 24 to April 25. I was expecting to be seen in February for bloods, but appointment didn't come until 1st April. I found this really hard as I had swung hypothyroid and was experiencing debilitating fatigue, depression and other hypothyroid symptoms, with again terrible sleep but in a different way. I've had a headache for a month that painkillers taken on two occasions don't touch. Also had an Ocular migraine for the first time.
April 25 moved to block and replace (40mg CMZ/100mcg levothyroxine). I've been on this for 2 days and feel so bad. I can't sleep and am getting about 3h at a time, but can barely get up and am in bed about 18h a day over the last two days. It's like I'm a comic book character that has been drained of life force and can't move. I think I also have an ear infection so maybe that's the issue, but I just can't muster the energy to get to the doctor to deal with it.
As an aside, I thought I had mild TED and Endo agreed, but Ophthalmologist thought it was anxiety as I had uveitis in the past. I'm taking Selenium anyway.
Family and my other history:
46F, family history of autoimmune disorders including Graves Disease. (Maternal grand father died from Addison disease, Mother has had Graves disease, Ankylosing Spondylitis, Psoriatic Arthritis, Lupus, Sjögren's syndrome, Raynauds. She's HLA B27 positive).
I've had two episodes of uveitis in the past (one anterior treated with steroid eye drops, one posterior treated with oral steroids). Childhood reactionary arthritis following yersinia infection. Investigated for Ankylosing Spondylitis a few years back, but joint pain had eased by the time the MRI came through so I was discharged without any further appointment as no inflammation evident on MRI.
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Right, so your FT4 was a woeful 6 just a few days ago. And had probably been under the bottom of the reference range for a while before that. So going straight on to 100mcg levothyroxine seems like it’d be quite a shock to the system?
I’ll admit that I don’t know lots about block and replace so I don’t know if that’s normal practice but… it seems to me that the sudden introduction of a decent amount of T4 might cause some initial issues, especially if you are already run down (ear infection makes it sound like you definitely are).
I think over time it will probably level out (the short way of saying your body will get used to the levothyroxine) and maybe that’s what your doctor was thinking?
Hopefully others who’ve had block and replace will see this post and chime in.
Thanks so much for your reply. Hopefully I will level out. I know it's early days so am not drawing any big conclusions, I just feel so awful I wanted to see if that was usual. Really appreciate you taking the time to engage x
Yes, good shout. I'll try and get to the GP tomorrow about my ear and if by Monday I'm not doing any better will call the Endo. Thanks for your good wishes, feeling pretty rubbish and it's really validating to be seen x
If I’m honest (but remember, I really don’t know much about block and replace!), it seems a bit heavy handed to put you on block and replace when the CMZ was working—your FT4 had dropped to 6.
But hyperthyroidism can be tricky to deal with—it’s rather more unpredictable than hypothyroidism and there isn’t a one size fits all solution.
The thinking was I could have more consistency on B&R and not have to change doses and have varying levels all the time. I was keen for that. But not seeing me for 4 months there gave me a lot of inconsistency!
So you started on 20mg carbimazole in Nov ? Your Free? T4 was considerably reduced by December,& your dose kept the same? Probably because still over range T4 but should have been checking again preparing to reduce.
Levels should really have been retested in February it was likely in range by then the carbimazole dose should have been reduced to stop level dropping so low.
Your low levels will be making you feel very unwell. I would have thought lowering dose & allowing levels to rise again would have been next step. Why did dr opt for B&R? did they explain?
Your symtoms for such low levels are likely to take time to resolve unfortunately. Things with thyroid take time. Even if 40mg carbimazole & 100mg levo are the exactly the right level for you it’s going to time to show how you settle on the adjusted dose. Then symptoms will begin to improve.
You need a retest after 6 weeks to see how dose change affects level, then it may need adjusting to ensure optimal levels.
Has FT3 been tested? The active thyroid hormone? What about folate, ferritin, B12 & vitamin D. Have you have celiac screen at all?
Do you have preservative free eye drops for your eyes?
I also get migraines, more so when thyroid levels high, doctors says they are unrelated, which I strongly disagree with. Altering propranolol was a huge migraine trigger for me. I was eventually able to reduce dose very gradually, but remain on low dose as migraine prevention. Have you stayed on a consistent dose?
Thank you for your detailed reply. I was told I would be checked 4-6 weeks which worked out at February but didn't get an appointment. I phoned to check and was told I was scheduled for March. I asked if it could be February as that was what had been arranged, and they sent me an appointment for April. It's been horrible tbh.
Ironically the Endo put me on B&R so that I would have some consistency and not changing levels all the time. I was happy with that as a plan, but didn't realise this would be the journey to get there. It's been horrific. I'm also scheduled for a TT. She said given my TRabs were so high at diagnosis it was unlikely I would go into remission on medication alone and so a medication only route would be years of inconsistency even if successful. I was glad to try B&R to give me an idea what I'll be like post TT.
I only FT4 has been retested. I had a full blood count in November and the GP won't repeat it, but it didn't include the things you've listed and I haven't been screened for coeliac. I do have eye drops but my eyes haven't been as dry since I started on the selenium so haven't been using them as much.
The propanolol I've just been using as needed. When I was really hyperthyroid I was taking 40mg 3x a day. As I came down I reduced that and have come off completely since I went hypothyroid because my RHR is usually in the 40s and 50s. TBH the GP told me to stay on it because of anxiety, but I don't feel like that's good for my heart or general feeling well as my hypothyroid symptoms have been so horrible. If I stabilise back up again I'll go back on it
Like PurpleNails I would have expected them to have tried titrating down the Carb before changing to B&R which did work well for me. I was on it for about 7 years but felt very unwell at first when they changed me over. It is only my personal opinion but I think they use too high doses. I asked to be on the minimum effective dose which for me was about 10mg carb and 50mcg Levo. Why take 40 and 100 if 10 and 50 works? The problem is it takes a lot of monitoring to find what suits and it is essential to measure fT3. I found that to stay well I needed it half way through range and over the years made small adjustments to keep it there.
Thanks that's really helpful info. I think they're just not able to monitor me as much as I need and so are trying to avoid lots of med changes hence the lack of titration. The Endos have been great (there's 2 thyroid specialists in the clinic and i see whoever i get on the day) in the appointments and the first doctors I've ever met who haven't just said "go away it's just anxiety", but this not being monitored and left medicated to feel awful has been really horrible. They haven't been retesting FT3 or TSH so I don't know what those levels are. The Endos are both thyroid specialists so I've not really been challenging their advice, and they've been patient letting me ask a lot of questions
It is important to be monitored frequently with a full thyroid panel until things settle. I had to get a second opinion and the new endo was great. He wrote to my GP asking them to arrange the blood tests every 6 weeks but to take no responsibility for dosing. I would email the results and how I was feeling directly to him for advice. This worked well and eventually things settled. Good luck
That sounds like a great system! She has promised to retest and review by phone in 6 weeks so I'm hopeful I won't have to go through this again, but the trust has gone. Thank you your replies, it helps to feel not alone!
So sorry you are having a rotten time. I can empathise. I relapsed with Graves disease in November 2023 (first episode formally diagnosed in December 2019). Like you, very high antibodies and FT3, FT4 levels beyond the measurable range. I posted on here before about having no appointment or blood test from Dec 2023 to October 2024. Suspect I went very hypo. Felt rotten.
I haven't been put on block and replace because my levels are pretty good at the moment but I am on a low dose of carbimazole - 5mg a day and now have 6 weekly blood tests. If my levels dip I will stay on 5mg and take levo. 20mg seems very high as a long term dose.
I would urge you to do research. A TT is a very drastic operation and you are left to the mercy of your GP most of whom do not understand thyroid conditions. I need to leave for work soon but YouTube has lots of good resources on long term antithyroid therapy for Graves and there have been many studies that show good outcomes on this regime. In the US for example, it is very usual to treat Graves with low dose anti thyroid medication for 18 months.
I still have some symptoms but I have come a million miles from the position where I literally could hardly walk and had to crawl up stairs on all fours. I will never agree to RAI or a TT or even partial thyroid removal. The endo care is generally pretty awful and it was clear that mine just wanted me off his list. I provided the evidence of the success of long term AT therapy and advocated very strongly. It felt uncomfortable but what's the alternative?
Thanks so much for your detailed reply, I really appreciate it. I agreed to the surgery and was keen for the idea of consistency it offered. I did a lot of reading and it seemed like the right choice for me. Supposedly just find my right dosage and stay on it forever, easy. Yes possible complications of surgery, but they seem quite rare and the surgeons here do a lot of TTs. And going on block and replace first will tell me if I'm a bad converter so I don't need to worry about that.
But I am now having second thoughts. My mental health has been all over the place. I don't know if it's the trauma of having to deal with doctors who are in a system that's not functioning, or the associated anxiety and depression that comes with fluctuating thyroid levels. Or of course my pre- existing mental health/ probably neurodivergent but lived a lifetime trying to fit in with a neurotypical world etc. Anyway, point is I think I might have been impulsive to have agreed so quickly and been governed by how I was feeling.
I'm particularly concerned after having been left by the Endo for 4 months without retesting and left to get so hypothyroid and feel so awful. I don't want to be reliant on doctors again and left like that. I'm kinda reliant on them anyway though, even staying on ATD and not going the TT route. Yes, there's a chance I'll go into remission, but the Endo doesn't think it's likely and this is a much more fluctuating and complex state to be in than just post TT. I just don't know tbh. Sorry this is a bit rambling.
Trouble is they just want rid of you so are happy to render you hypothyroid for life to get you off their books via a TT. Being hypo for life on levothyroxine is not always a bed of roses in fact is can be unmitigated suffering.
I didn’t have Graves but a form of thyroid disorder that is closely related with vacillation between hyper and hypo states caused by TRAB but in my case my thyroid atrophied away so I became hypothyroid for life. It has been a pretty horrible journey but I’m ok now. I ended up taking NDT and feel a lot better on that than levothyroxine. I have had zero support from surgery who thinks it’s snake oil. It isn’t. Mine wasn’t diagnosed until my thyroid had croaked and I’d been to hell and back many times.
I do hope you start to feel better and the b&r suits and you can keep on it for a long time. It can be very awful when things go haywire I remember how bad I was when the thyroid hormones went up into the stratosphere I went totally crazy then crashing back down to nothing and zombie mode.
Once diagnosed with Graves Disease and started on treatment - either an AT drug or with Block & Replace - this is meant to enable the patient to be as comfortable as possible -
as ' normal ' as possible while we wait for the immune system to calm back down again.
The AT drug either Carbimazole or Propylthiouracil - dampen down your immune system response and dose dependant block your own new daily thyroid hormone production while we wait for your immune system to calm back down again and hopefully your thyroid reset itself without the need for any drugs.
I believe the treatment of both options needs close monitoring - possibly more so if on just the AT drug - and that regular blood tests are run for the TSH + T3 + T4 every 6-8 weeks and the AT medication titrated down as the T3 and T4 fall back down into range again.
Since Block & Replace fully blocks your thyroid hormone production the T4 Levothyroxine is also prescribed so your T3 and T4 do not fall too far through the ranges with you then experiencing the equally disabling, , if not worse symptoms of hypothyroidism.
I would think the aim is to try and maintain your T3 and T4 at around mid point in their ranges and hopefully symptom free of both hyper and hypo symptoms - which again can be a little confusing as some symptoms ' sit ' in both sets of symptoms.
You might like to dip into Thyroid uk - the charity who supports this patient to patient open forum where you read around further on all things thyroid and there is a very thorough list of both hyper and hypo symptoms that you might like to use a check list and monitor yourself on as you go through this first phase of Graves - thyroiduk.org
The TSH will be the very last bio-marker to move, if it ever does, as it is the Graves antibodies circulating in your blood that have got stuck, and are pushing down on the fine hair like follicles of the TSH receptor sites which in turn pushes up thyroid hormone production.
Please give the T4 - Levothyroxine - time to build in your body and hopefully in a week or two you will start to feel more comfortable.
It would seem the NHS is under continued pressure throughout the country and with systems backed up and O/P waiting list times not being met.
You say you are waiting for a thyroidectomy - what criteria is placed on the timing of this operation - do you need your T3 and T4 and antibodies at target levels before surgery ?
Graves is an Auto Immune Disease which can wax and wane throughout one's life - and for which there is no cure - and simply removing the target of the immune system attack does not stop Graves in ' its tracks ' as we are looking at a long term chronic health condition
There is usually a genetic pre-disposition with Graves - as you have acknowledged.
Did you Mum have a thyroidectomy and now with Graves Disease and Primary Hypothyroid ?
The NHS generally offer a treatment window with an AT drug for around 15-18 months and if by then you or the endo team haven't ' found remission ' through treatment with the AT drug, definitive treatment, either RAI thyroid ablation or a thyroidectomy is encouraged.
The most recent research is suggesting that the longer the patient stays on the AT drug the better the long term outlook for the patient - though fully accept that for some patients definitive treatment is the only option :-
I found the most well rounded of all I researched ( though 8/10 years too late for me as I have Graves and went through RAI thyroid ablation in 2005 ) that of Elaine Moore's books and now archived website :-
I too lived with mystery symptoms similar to what you describe though my uveitis in both eyes was laser treated at Moorfields some 15 years prior to getting a diagnosis of Graves Disease.
Mum had a partial thyroidectomy, this was 50 years ago now when they still did that. She says they removed 7/8s of her thyroid. AFAIK she hasn't had any follow ups with endocrinology, but had always seen a rheumatologist for her other autoimmune conditions. Now I'm going through the same, I think they should have been monitoring her and she probably has had fluctuating thyroid levels all her life that have been untreated. There's good reason why they don't do partial thyroidectomies any more for Graves.
I'll look out that book and website, thank you. I've mainly been reading journal articles. There isn't as strong an association between Graves and Uveitis as there is between Ankylosing Spondylitis and uveitis, so it's really nice to meet someone else who's had that combination! Although I'm sorry you've had to deal with it.
Ok then - I've just learnt what AFAIK is - thought it another AI disease !!
Graves is a poorly understood and badly treated AI disease - and mainstream medical seem to think we are ' better off ' living with Graves but without a thyroid - and for most - if they are well monitored and stay on the AT drug long enough - Graves will likely burn itself out :
You must not be considered for RAI thyroid ablation as this will likely exacerbate any eye issues you already have - and quite why this toxic substance is still a first line treatment option in what we understand to be a health care setting - beyond me.
P.S. ' Supposedly - finding my right dose and staying on it however ' is simplistic -
and you can't know how well you will be able to convert T4 into T3 post definitive treatment - living without a thyroid is a whole other headset to where you are now :
A fully functioning working thyroid is supporting you on a daily basis with trace elements of T1. T2 and calcitonin + a measure of T3 at around 10 mcg + a measure of T4 at around 100 mcg -
with T3 being the active hormone and around 4 times more powerful than T4.
Currently there are 3 recognised treatment options for hypothyroidism -
T4 - a synthetic pro- hormone that your body needs to be able to convert into T3 :
T3 - a synthetic active hormone that runs the body much like fuel runs a car :
Natural Desiccated Thyroid - the original treatment for hypothyroidism - derived from pig thyroids, dried and ground down into a powder which is medically graded and then made up into tablets/grains and capsules and contains a stated content of T3 and T4 in each grain - and contains all the same known hormones as that of the human thyroid gland.
Currently the NHS will only prescribe T4 thyroid hormone replacement - the cheapest and most easily managed option - and should this not restore your health and well being you will need to be assessed as to ' your need ' for any other treatment option.
NDT - the most expensive treatment option has now been Blacklisted to new patients -
and T3 has become something of a post code lottery with some ICB areas and hospitals facing financial constraint and endocrinologists restrained in their treatment options.
I was refused both NDT and T3 by the NHS back in 2018 when very unwell and now I self medicate and buy my own thyroid hormone replacement and much improved.
Up until around 2000 your primary care doctor had the option of treating you with all 3 treatment options - now in primary care your treatment option is an anti-depressant.
Obviously if you can afford to go private there is a very different landscape and all treatment options available .
The thyroid is a major gland responsible for full body synchronisation from your physical ability and stamina through to your mental, emotional, psychological and spiritual well being - your inner central heating system and your metabolism and I do not believe easily replaced - by 1 little tablet for the rest of your life.
I'm really sorry you've been denied the healthcare you need. It's an awful situation to be in. Not just for the expense of having to do it yourself, but all the worry and trauma of being dismissed and ignored by the very professionals you need to give you actual healthcare. It's a really sorry state of affairs we're in. I spoke to my Endo about what they would offer if I turned out to be a bad converter. She was one of the authors on the BTA guidelines on this so is well informed, and she said that if I turned out to be someone who didn't function well on T4 alone, I would also be given T3 and would stay on her/Endocrinology caseload forever rather than be discharged to my GP. In that respect I have a winning ticket in the postcode lottery. The nice thing about being on block and replace first is that I should learn if that's me before the thyroidectomy.
But it is a big thing to rush into, and I am now more thinking I should try medication first for longer. My head has been all over the place over the last 8 months, and I trust my doctor less now she left me without review for 4 months and going very hypothyroid. I don't want to be at the mercy for the rest of my life now. Even if it is more stable than fluctuating levels trying to medicate, probably relapse multiple times etc. It's not more stable if they don't monitor me properly.
Hi, you are having a horrible time of it. I had Graves in 2012/13.
I started with four weeks on 20mcg carbimazole which when I had the four week blood test hadn’t made enough difference and I got a letter from my Endo (who I hadn’t seen at that point but who file shares with my GP ) telling me to get more carb and double up to 40mcg. I took the 40mcg for the next two months - no further blood tests - by which time I was very hypo.
The endo I saw on my first visit suggested stopping the carb for ‘a few days’ I stopped it for four days. At the same time I started taking Levo. I started on 25mcg a day and gradually increased over a few months until I was taking 100/125 on alternate days. It took exactly a year and the day after seeing my endo I stopped both drugs.
As you say being hypo is really horrible - just in a different way to being hyper.
I can remember feeling pretty awful in the beginning before I got started taking levo with the carb and the first time I needed an increase in levo I felt as if I was becoming hyper again but someone on here said I was probably needing more levo which turned out to be the case and every time I needed more levo I felt the same.
Once I got up to the 100/125 I felt fine. I have asthma so I was never given propranolol- I just had to sit it out until the carb worked. I can remember feeling pretty awful for the first three months before I started on levo. It was coming up to Christmas and my husband who clearly didn’t quite understand how bad I was feeling suggested that I host a Christmas party for all of our neighbours. Needless to say I put him wise in the way only someone with Graves could and I did not host anyone. In fact I left the party early when it finally happened because I just wasn’t finding it fun!
Like you I was utterly exhausted at the beginning and could have slept round the clock. Fortunately the children had all left home and husband was out working so it didn’t matter but it was a horrible time. In my case I lost so much weight that I looked great on the outside - inside I felt really dreadful.
Eventually things settled down though and I felt very good on b&r. I didn’t have TED but my eyes felt absolutely awful and I used to get double vision and found it difficult to read for any length of time or even watch TV. I used preservative free eye drops all the time and that helped but it took a while.
I also took high strength, slow release vitamin C capsules that I felt made a difference.
Good luck with it all. It mudt be so soul destroying when you can’t get regular appointments
Thank you so much for sharing your experience. I relate so much and it's so helpful to know there are others out there with the same story! I'm really glad to see you settled on B&R and found some stability on it. I'm hoping for the same. You've given me hope!
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Block and replace or add back - which method would be best
UP AND COMING ENDO APPT
Graves disease antibodies 
unstable after 2 years treatment
