Hi there. I was recently diagnosed with very mild hypothyroidism, which feels like such a relief to explain all my tiredness, depression and unexplained weight gain!
I'm really struggling to get my head around how the dosing system works though and would really appreciate your insights as my GP seems fairly unwilling to explain this to me. Basically, I was started on 100mcg Accord and felt amazing the first few days on that. Then by day 7/8 I was irritable, could barely sleep and just felt totally wired (like I had hyperthyroidism!). So I stopped taking the levothyroxine and started doing the maths.
As I understand it, levothyroxine has a half life of about a week - on that basis, with a daily dose doesn't the amount of levothyroxine in your body just keep going up? I made a spreadsheet so I could see at what point I felt awful. The GP then suggested 50mcg but by my calculations I would feel terrible again within a week. So I'm on a negotiated 25mcg (Teva) and feeling totally tired and depressed again. And cannot stop farting!
Can anyone explain to me how this works? What am I missing? If I try 50mcg am I going to feel shite again within a week or has my spreadsheet model missed something?
Hope I've explained this enough to make some sense to someone! Thanks in advance for any help
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Also, the accord seems to make me feel like I have a lump in my throat, almost like that feeling when you're about to cry. Does anyone have any idea what that is?!
I couldn't find a research article on the topic, but this reddit post (reddit.com/r/Hypothyroidism... has a graph that shows how long it takes to get to a stable level.
[ Edited by admin as the link had a close brackets immediately after it. That meant the link included the bracket and wouldn't work. Removed. Links have to be surrounded by spaces or new line/paragraph. ]
Thank you, that's super helpful! Can't believe I didn't find it already. This sounds like maybe my body needed some time to get used to the dose. So maybe I need to try 50mg now and see how I get on with that gradual increase
That is a very helpful graph and does help to illustrate what is happening and why it is said to take six to eight weeks to stabilise.
However, as with almost everything to do with thyroid, it simplifies.
At the same time as this process is going on, the body will reduce TSH (because the hypothalamus and pituitary react to more thyroid hormone in the blood). The lower TSH will result in the thyroid producing/releasing less thyroid hormone. Therefore the need for the thyroid hormone being taken increases.
And the whole system will be changing how much is converted to T3 (etc.)
That is not meant to be critical of the reply, or the graph (and comments there), but to make sure no-one takes it as a literal statement of what will happen.
Your calculation should have shown 50mcg circulating after 1 week on 100, yes? However if you start on 50 mcg, only 25 will have built up after 1 week. After 2 weeks, 25+12.5 = 37.5. After 3 weeks, 25+12.5 + 6.25 = 43.75. Etc. The half life is how fast levels decay, but also how fast they build up in the circulation from what i understand.
50 mcg is the standard starting dose so your doctor started you on too high a dose, and it was probably quite a shock to your system. Especially if you have low iron, b12, folate, and/or vit D as so many of us do.
Some people cannot tolerate Teva.
I get a lump feeling when i'm overmedicated or raise too fast.
The admins will be around in the morning to give additional suggestions.
It would help them if you post your thyroid lab results together with the reference ranges for each test. Also iron/ferritin, B12, folate, and Vit D if you have them.
Also, yes the cumulative levels of levothyroxine after one week are 530mg (not 25mg) because the elimination half life is a week and the doses are daily. I figured that this is the level at which my body goes haywire! But perhaps it wouldn't if that cumulative level was reached more gradually.
Well that's just fancy math now 😂 No, I just find it much easier to think in terms of the actual dose I'm taking.
"But perhaps it wouldn't if that cumulative level was reached more gradually."
Yes, exactly. And on top of that you have to add the effects of the (TSH) feedback loop as explained clearly below. Plus the body does not work in a linear way : X dose change != Y change in TSH. That's why you need to stay stable at a single dose for 6 weeks before testing. I've had tests - especially in the beginning when adjusting doses - where TSH goes up and down and you can sort of see it oscillating as it overshoots and then goes back up again, adapting to a dose change.
I'm not in the UK, but from what I understand, it's difficult to get them to test FT3. Many people order their own tests, either a finger prick test or a blood draw though e.g. medichecks, blue horizon, and others thyroiduk.org/help-and-supp...
You should get all 3 tests together whenever you measure, otherwise the results are meaningless: TSH, FT3, FT4 , and worth getting the anitbodies testsed at least once if NHS hasn't tested them.
The test should be fasting with nothing but water, around 9 am, and wait to take your Levo until after the test (so that the last dose of levo is 24 hours prior to the test). Please read this pinned post on testing/timing protocols: healthunlocked.com/thyroidu...
I don't take that much even after more than ten years on levothyroxine!
Many would be overdosed at that level. And even among those for whom it would in the end be a reasonable dose would feel terrible starting on that much.
If that calculation were so right, we simply wouldn't see numerous different formulas being published and discussed by endocrinologists.
helvella's calculation document and spreadsheet can be can be found by following this link:
helvella - Estimation of Levothyroxine Dosing in Adults
A discussion about the use of formulas to estimate levothyroxine dosing. Includes link to a downloadable spreadsheet which calculates several of these.
They appear to claim that any TSH within reference interval is euthyroid:
The treatment is replacement with oral levothyroxine with an initial starting dose of 1.1 to 1.6 mcg/kg/day to achieve a euthyroid status, i.e. TSH levels of 0.4-4.0 mU/L
They bizarrely break off to mention levothyroxine injections - which are obviously not viable for permanent dosing. But completely ignore liothyronine:
The alternative preparations, such as injectable levothyroxine, are reserved for specific situations like malabsorption.
Their reported TSH after treatment:
The average TSH level after treatment was 2.09 ± 1.18 mU/L.
That is a big range! 0.91 to 3.27.
I find this an unlikely claim. All too many only realise years later that they'd actually had thyroid disease long before seeing a doctor, and often long before the most obvious symptoms developed.
The mean duration of disease was 6.52 ± 5.36 years with a preponderance of female gender (83.5%, n=421).
I found reference to a study which said:
Another study by Di Donna V et al. (2014) found a correlation of levothyroxine requirement and body weight, BMI, age, and preoperative mean corpuscular volume,
Given that MCV is widely regarded as indicative of B12 and/or folate deficiency, or iron deficiency, I'm sceptical of this. (Paper not accessible.)
However it is good that they recognise changing makes of levothyroxine is an issue.
Also good that they have read and reference diogenes, et al., and Jonklaas:
The signs and symptoms should be carefully assessed, as the overreliance on biochemical analysis of TSH is shifting now
Well it just goes to show that we’re all different and all respond differently to dosing doesn’t it. Personally I have been treated for autoimmune Hypothyroidism for 30 years but had symptoms for 10 years before that (was told borderline). Had I known back then what I know now I wouldn’t have accepted that.
I suspect that's what they used to start me on 100mg but surely it depends how hypo the person is? Given I'm only a bit off, I think 100mg starting dose was far too high
being able to work the dose out with maths would be great...
but will send you potty trying .. there are too many variables and unknowns due to the way the bodies regulating system works.
adding some levo raises T4 ( initially) which lowers TSH , (but how much /how fast is extremely individual, and impossible to predict)
lower the TSH and you change the amount, AND ratio of T4 :T3 produced by the thyroid itself ... (how much / how fast is again , not possible to predict for the individual).
TSH is affected by both T4 and T3 levels ( and a lot of other things)
TSH can take anywhere up to 6 weeks to change in response to a new level of T4/T3 ... but it can also change much quicker than that ,and just for fun , it can also take much longer than that .
and during those '6 weeks' the levels of T4 /T3 are themselves changing increasing as the dose build up and at the same time lowering as the thyroid lowers it's output .. and these changes continue to affect the TSH level.
The total amount needed in the blood of the individual is not very predictable either. there is a very rough guideline suggested total dose of 1.6mcg / kg body weight , but in practice some need less than, this some need more.
plus a multitude of other variables/ unknowns.
A dose that is actually 'about right' for the patients needs will often feel 'a bit too much' to start with .. not because the level in the blood is too much per se , but because the body has been used to 'running a bit slow' and objects a bit to the sudden influx of higher hormone levels (stimulating it to go faster) the body needs time ( months) to catch up and get used to it , and also to adjust and repair systems that were downregulated due to low thyroid hormone levels .. so eg anywhere between 75mcg and 150mcg might end up being the right dose for you ................, but if you start with 100mcg 'out of the gate' , it might make you feel overmedicated even if the dose you need actually ends up being 125mcg ... whereas 6 weeks of 50mcg , then increase to 75mcg , then 100, then tweak up or down a bit depending on results to 112.5 or or 87.5 .... that kind of thing ... if often a better way to do it .
Newer guidelines are telling GP's they can start at 100mcg , and your GP has gone with that suggestion , but there have been several people through here this year who found starting on 100mcg is just too much to start with., and who had to pull back a bit and start lower ( i started at 50mcg for 7 wks then went up to 100mcg in one go ,and ended up on 150mcg a few months later , but that is faster than would suit some people , 25mcg increases are a much safer bet)
its a case of finding the balance between getting up to the best dose as efficiently as possible , without going too fast for the body to adjust.
The upshot is that the only way to assess the effect of a dose of levothyroxine , is to pick a dose based on experience/ guestimate , stick with it for at least 6 weeks to allow symptom response and bloods to settle, test bloods once everything has ( hopefully) had time to settle down ... then adjust.
the half life is relevant , and it does explains why lots of us first start to notice a new dose around 10 days .... but it doesn't change the fact that the only way to asses a dose is try it for at least 6 weeks and wait and see what has happened to symptoms and bloods at the end of that time period.
This makes so much sense! Thank you. Why don't GPs explain it like this?! This is all a bit depressing though as I was all set to try and get pregnant (given my age, time is of the essence) and now I have to wait until my TSH is below 3, which sounds like it may be months away...😫
but it is what it is .. the last thing you want is to get pregnant with unstable thyroid hormone levels .. the developing fetus relies totally on adequate maternal thyroid hormone levels for the first approx ?11 wks of life,... until it has grown it's own thyroid and that has then started producing adequate T4 /T3 of it's own .
so the very time the fetus needs adequate /reliable thyroid hormone levels , is the same time you may not even know you are pregnant ...and inadequate thyroid hormone levels are a potential cause of miscarriage ,and can affect fetal development .
welcome to Hypothyroidism ~ an enforced lesson in patience , whether you wanted one or not . Try not to panic about time .. once you have better / stable thyroid hormone levels you stand much better chance of conceiving AND having a healthy outcome .
I found these new draft guidelines for thyroid / pregnancy the other day .. haven't read em yet , but you may find them useful : healthunlocked.com/thyroidu....
[edit] .. it's hard to read as it's a draft copy , but see charts on page 14 -16 for recommendations on TSH level / dose increase as soon as conception is confirmed and monitoring timescales
Yes, my fertility consultant initially said that but as I had already started the drugs for this transfer he was willing to accept a result below 3. Wish he had made it clear that this was potentially a long process to get fixed and that it was a condition to proceeding with the embryo transfer! Anyway, like you say, an exercise in patience. Will be good training for if I manage to have a child eventually I suppose! 🙄
some other practice that may prove useful one day:
Baby dressing .. practice putting octopus into string bag
Toddler managment .. Practice taking a herd of baby goats round a supermarket .. pay for anything they / break /consume on the way round.
Get car ready in advance ... throw broken biscuits around inside, and smear something pink and sticky into all the corners.. snap off some of those clever switches on your steering wheel... smear the pink stick stuff into the rest
Teenage daughter ..... there 's no way to prepare for that.
The total amount needed in the blood of the individual is not very predictable either. there is a very rough guideline suggested total dose of 1.6mcg / kg body weight , but in practice some need less than, this some need more.
That is the dosing that is possibly required - not the amount in the blood - which would, of course, be from Free T4 (maybe Free T3) tests. I know you know - but it read a touch less clear than you usually manage!
true .... i knew that wasn't quite right as i was writing it (trying to juggle too many ideas while wondering whether to let british gas install a smart prepayment meter, or tell em to bugger off) .. thanks for picking up and clarifying
But I'm a conspiracy theorist I do not want any more potentially intrusive hardware in my house. Besides they work on behaviour changes. I have a water meter (installed against my wishes) and now fret about the water all the time.
i've already changed my behaviour yrs ago.. to well below 'miser' mode on all settings ..... my lightbulbs all use 2.4 or 4 .3 watts at most.. (i allow one in the daughters bathroom that uses 20 for positive mental health reasons). my thermostat is set to about 13 ,,and we use 3 and a half radiators in a 7 bedroom , 3 storey house. nobody dares to put more than 1.5 inches in my kettle or i'll bite them .
i just object to the fact that, currently i can take the key to the shop on the corner and make the leccy/ gas come back on instantly if it runs out .. whereas a 'smart one' will apparertly take 'up to an hour' to put the credit on ...... and if you want to do it manually to get it to come back on 'now '.....you have to imput a 20 digit number ( without a proper keypad )..,, smashing... not .
Just picking up on Teva - contains mannitol, makes a lot of people unwell.
Accord - if it suited you, make friends with your pharmacist and try to get that consistently, it is also branded Almus and something else so all the same. Contains lactose but not a problem if you are ok with lactose.
GPs will say brand makes no difference but patient experience says not. We generally find changing brand causes a whole load more ‘adjustment’.
Some of us split a 100mcg or 50 mcg tablet to get the dose we want.
Accord is only also branded Almus - the other name (under which it used to be available) has disappeared. (Not mentioning name to try to avoid confusion!)
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How am I supposed to function on 50mcg levo (base dose) daily without a thyroid?
how long does it take for t4 to come down after reducing dose?
Working life at the beginning of Hypothyroidism. 
Does the dose of T4 and T3 sound too high
Graves Disease/Hypothyroidism and work life
