How long does it take to get used to a dosage? - Thyroid UK

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How long does it take to get used to a dosage?

22 Replies

I got my diagnosis 10 months ago so I'm still figuring things out really.

I had bloods done 3 weeks ago (8weeks after increasing to 125mcg) so I've been on the same dose 11 weeks.

When I had bloods done I remember thinking 'I'm not quite there and I'd like a dose increase' but I also felt pretty normal again.

I'm usually strict with my routine so I take levo at night about 9:30 but we eat about 5:30 so that's plenty of gap. I take vitamins and iron on alternate days but the last dose by 5:30 at the latest. I am GF.

This past couple of weeks I've felt like I'm slowing down again, which is disappointing. My brain fog and OCD have almost completely gone which is life-changing so I'm not complaining! But I've noticed my speech is slurring a bit again and I've got prickly/itchy skin, I'm also getting more sensitive to the cold again.

I was hoping to sort of brainstorm here since I've noone in real life to chat these things through with!

Things to factor in:

We had quite a stressful weekend involving a breakdown on the motorway and an expensive tow home. (I can cope a lot less well with stress, physically, these days)

We got a puppy so I'm getting a bit less sleep (but not much, maybe an hour less a day?)

I've not taken vitamins or iron in a week because I kept forgetting until too late in the day. (Back on track now!)

I missed a days levo in the week.

My cycles are starting to (finally) lengthen and I'm currently on day 28 which is the longest cycle I've had in 16 months.

So finally, I suppose my question is; at what point should I consider a retesting to see if a dose increase is needed?


TSH -1.37 (0.27 - 4.2)

FT4 - 21.6 (12 - 22)

Free T3 - 4.8 (3.1 - 6.8)

Ferritin - 18 (13 - 150)

Vitamin D - 131 (75 -175)

Folate - 41.4 (8.83 - 60.8)

Active B12 - 92 (37.5 - 188)

22 Replies
Buddy195 profile image

If my ferritin was as low as yours I know I’d feel awful. What dose of iron you supplementing with? How long have you been taking it?

in reply to Buddy195

I take 3 spatone a day, plus a solar gentle iron which is 20mg a day.

And a ferrous sulphate which is 200mg.

I also take a 200mg vit c tablet.

It's a reasonably new regime though but I'm hopeful it will work!

I'll do another iron panel in 8 weeks or so to check progress.

waveylines profile image
waveylines in reply to

I think its your low level of iron that is flooring you rather than a need to increase thyroid hormones. Hope your new iron plan works and you feel a lot better soon.

in reply to waveylines

Yes, it definitely needs work! It was just that I felt great for awhile and have dipped. Since my ferritin level hasn't really moved in 3 years I wondered if it were levo that needed adjusting since that is more transitory.

Hopefully I'll see some improvement soon with my iron levels!

waveylines profile image
waveylines in reply to

It maybe that now you have got your thyroid hormones are higher your metabolism will have increased and so the need for iron will be greater.

in reply to waveylines

Oh ok. That makes sense! Hopefully I'm doing enough for now. 🤞🏼

Buddy195 profile image
Buddy195Administrator in reply to

🤞your iron levels improve on that regime

in reply to Buddy195

Hopefully! It's only ever been as high as 51 and that was 4 years ago.

Big push now on ferritin and iron. 🤞🏼

SlowDragon profile image

Are you vegetarian?

Look at increasing iron rich foods in diet

Eating iron rich foods like liver or liver pate once a week plus other red meat, pumpkin seeds and dark chocolate, plus daily orange juice or other vitamin C rich drink can help improve iron absorption

List of iron rich foods

Links about iron and ferritin

Great in-depth article on low ferritin

This is interesting because I have noticed that many patients with Hashimoto’s disease and hypothyroidism, start to feel worse when their ferritin drops below 80 and usually there is hair loss when it drops below 50.

Thyroid disease is as much about optimising vitamins as thyroid hormones

Post discussing just how long it can take to raise low ferritin

Never supplement iron without doing full iron panel test for anaemia first

Post discussing why important to do full iron panel test

Why low ferritin needs improving

Helpful post about iron supplements and testing

Post about iron supplements

in reply to SlowDragon

Yes, and veggie.

Try to eat leafy greens everyday with lemon Juice plus the but C tablet for good measure!

Using cast iron pans and a cast iron fish as well so I'm throwing everything bi have at it at the moment!

Will test again in 8 weeks or so. If no marked response will consider eating meat or pate short term to get levels up.

Do you think it's the ferritin that's made me dip? Despite it being consistently low for years?

Felt good on levo for a few weeks after the increase.

SlowDragon profile image
SlowDragonAdministrator in reply to

Extremely difficult to maintain good iron/ferritin with Hashimoto’s and vegetarian diet

It can take man6 months to improve ferritin levels

Important to do full iron panel test 2-4 times a year when supplementing iron to check iron not going too high

It’s possible to have low ferritin and high iron

in reply to SlowDragon

Last iron panel was:

Iron - 13.2 (10 - 30)

UIBC - 45.5 (24.2 - 70.1)

TIBC - 59 (41 - 77)

Transferrin saturation - 22 (20 - 55)

SlowDragon profile image
SlowDragonAdministrator in reply to

So you definitely have work to improve low iron and ferritin

tattybogle profile image

missing a day's dose (if you didn't replace it ,) effectively means you've had a week at 100mcg / day. so even though back on track .. you can expect that to have had an effect. So you do need to give it at least a couple of weeks back on taking 125 each day to get a true blood reading....... The fT4 will be back to the right level for 125mcg within about 7/ 10? days on 125.... but your TSH might have noticed the slight drop ,so it has to have time to notice dose is stable back at 125 again and react accordingly .... how long this takes is a 'how long is a of piece of string' type question.

It's also perfectly possible your TSH didn't bother at all and didn't move , but it's something to consider when timing next test.

The last 3 times i've altered dose by just 12.5mcg , (and was paying more attention to how i felt each week) i noticed that for me the first 5 /6 weeks were a bit different every week , and it wasn't until about 8/10 weeks that i felt 'settled '.

The one exception was when the dose was reduced too much from112.5 to 100mcg... that time it was pretty apparent (due to constipation ) that it was 'wrong dose' within a week , but i was patient for 6 weeks and it didn't improve at all i just felt worse over time.

You're getting pretty high up on fT4 range on that first set of 125mcg results, and i'm not convinced that over range T4 is entirely 'problem free' ...i think it brings it own issues/risks.. Some people do seem to need it high to get enough fT3 out of levo, but in an ideal world where getting T3 was not such a pain, you'd want T4 and T3 to be more balanced . So if you retest at 125 in a little while and find that your results still look so high on FT4 ....i would start to consider whether trying to increase T3 and lower T4 level might be they way to go rather than increasing T4 any further.

However if you have a GP who only looks at TSH , you might be able to get an increase , because TSH is still over 1, , (but if he see's that fT4 level he'll more than likely be asking you to reduce , and refuse an increase ... just one more example of why just going off TSH for monitoring dose is stupid... Your TSH says there's plenty of room for an increase, and your fT4 says probably not , or at least not much .. if you did increase at this point i'd only add 12.5mcg at most and wait to see the result of that ,

I do think that the combination of the 'motorway day out' ,the 'puppy alarm clock', and the missed dose are enough of a combination to explain feeling a bit 'off' for a while.. so i wouldn't be too quick to think an increase is the right move.

Stress, whether physical or emotional, knocks me more than it used to nowadays too .. a row with a 14 yr old would really knock me in a physical way the next day ..strangely much more than 'a day over-doing it in the garden' would.... and i imagine the 'motorway day' was not at all pleasant emotionally.

in reply to tattybogle

Thank you Tatty!

I'm finding my emotions around my health can be difficult to manage. Having had 2 weeks of slowing down (and yesterday feeling like I did when I was very undermedicated) drags up all those 'helpless' feelings and that life is going to revert back to how it was and I was so miserable that it all spirals out of control!

I think I knew riding it out was going to be the right answer really but it's so blooming difficult to be patient! It is not something I'm well known for..!

Thinking back on it I think I messed up the timings of that test so I think It was actually about 36 hours since taking levo so I think that could mean I have a 'false low' in the results? Although I don't feel over-replaced. I was tempted to speak with the GP to see if she would increase my dose to alternate days 125/150 based on TSH but I don't want to boost T4 well over range, and I had to work to get an increase to 125 with a TSH of 3.99 so I'm not convinced I'd get anywhere anyway!

I was confused by the results though - I expected TSH to be lower based on the T4 result.

I'm really throwing everything I have at raising ferritin because that's the last vitamin to be brought into line, and I'm really hoping that will improve my conversion because, while it's not terrible it's not great either and I really don't want to have to go to the expense of a private endo if I can avoid it.

Stress these days is just ridiculous. Any minor thing and I need a nap. Motorway day was indeed stressful... As was the £4,000 quote to fix it...!! Good job we've got a puppy to distract us, right?! 🤣

tattybogle profile image
tattybogle in reply to

4K.... Ouch ! ( iv'e bought trucks for less than that )If it helps with the 'patience'..... 10 months is really 'not long' for a body to adjust, in thyroid metabolism terms.

And 12 weeks on a new dose is basically just the first stage.... it's more interesting to observe what happens over the next few months... sometimes slow improvements continue to build if you just 'go steady' and don't over do it with boom and bust activities. Sometimes it confirms your thought that it's not enough yet .

Sometimes it teaches you how you can go through bad patches that resolve by themselves , (that if you'd changed dose you would have attributed the improvement to new dose)

Also ....sometimes TSH /fT4/3 change again from the first blood test on a dose.

If you increased dose now you would lose that chance to observe and learn.'s useful for future interpretation of blood results....

Is your TSH same or is lower or has gone up again after a few more months on 125?

Is fT4 is still top of range, or has the relationship between fT4 and fT3 changed as body has got used to functioning with TSH stimulation at 1 ish. ?

(or... like your next results on same dose bear no relation to logic and leave you confused but at least aware of how different your blood results can be on same dose a few months later. )

so it's often smart to wait a while longer then you want to .. and may mean you get there quicker in the end ... if you did manage to insist on increased dose now.. it probably would send fT4 way over , and confirm to GP that 125 is more than enough for you .... so they might then decide to reduce to less than 125, and you'd be up and down for months while they did this... and then you'd have to argue all over again for 125.. but by that point GP now has more ammunition to say " No , we tried letting you have more already "

So it might be best for now to play with the puppy and tell yourself you're not doing 'nothing' .. you're gathering evidence...


re. 'confusing TSH, not as expected'.... i had TSH 6.8 before Levo

It was 2.9 on 50mcg .

it was 2.5 on 100mcg.

It was 2.7 on 150mcg.

eh ??

When i did more than 150.. (I can't remember exactly how much more , but it wasn't much)..... it was 0.001. and fT4 went way over.

When i returned to 150mcg (for 13years) it was 0.05 to 0.5 ish from then on.... while my fT4 wandered around from 49% to 130% for no obvious reason.

So for some of us blood results are only part of the picture, and should be taken with a pinch of salt.

in reply to tattybogle

I'm sorry I didn't reply. I lost all ability to concentrate and then decided I'd come back when I had new results!

So they've all gone in the wrong direction. 🤦‍♀️ but it at least vindicates why I feel so rotten.

TSH - 2.81 (0.27 - 4.2)

FT4 - 19.3 (12 - 22) 73%

FT3 - 4.2 (3.1 - 6.8) 29%

was previously

TSH -1.37 (0.27 - 4.2)

FT4 - 21.6 (12 - 22) 96%

Free T3 - 4.8 (3.1 - 6.8) 45%

I don't really know where to go from here; ride it out for a few more weeks or petition the GP for an increase but I don't have much room for increasing in terms of T4.

tattybogle profile image
tattybogle in reply to

so .. especially if we consider your previous fT4 21[12-22] might have been a false low ( you said Levo taken 36 instead of 24hrs before test).... ...then the latest result of 19.3 does suggest that fT4 has fallen quite a bit (which would agree with TSH now being quite a bit higher ... (i'm assuming you took levo 24hrs before this test to get proper fT4 result ? , and TSH was 'same time of day' as previous test ?)

And fT3 is also quite a bit lower now .

If you wanted to try an increase to alternate 125/150mcg then since it must now be about 3 months on 125mcg ? ....i suppose you could reasonably tell GP you've tested TSH and got 1.37 at 8 weeks , but then felt slow again , and have now tested 2.81, so since TSH is clearly still rising and you feel symptomatic again could you increase slightly to 125/150 to see how it goes ... ( i wouldn't mention the fT4 results unless they ask... they might be quite willing to allow an increase due to TSH clearly rising , but less willing if they know fT4 is 'near the top' of the range )

They might not accept private results as accurate , so they might feel they need to do their own before increasing dose... Do your GP's normally test TSH AND fT4 .. or just TSH ?

in reply to tattybogle

So this test was done at 7:30 and previous one was done at 8:30.

I left 25 hours between dose and test this time. Which I know is a bit too long but the best I could do! 🤦🏻‍♀️

It's been 14 weeks on this dosage. Luckily (!) For me GP only ever tests TSH.

tattybogle profile image
tattybogle in reply to

Ok....... so if GP want's to do his own ,, make damn sure you don't give them your arm after 9/9.30/10am.. and if it comes back lower than 2,81 . you can show off your superior knowledge of TSH's diurnal rhythm and explain it's lower because TSH falls gradually over that day from middle of night to it's lowest at around 2/3pm each day.

Whatever you do, don't let them do a TSH test much later than 10am..even if it means waiting a few weeks for a blood appointment at the 'right' time Your best argument for dose increase is that TSH of nearly 3, if it came back nearer 1 their first reaction will probably be to say no, and you'd have to fight much harder.

During lockdown i once waited 5 weeks for an appointment, but it was worth it .. now they have the evidence i wanted them to have, they'll leave me alone (on the dose I want) for ages.

in reply to tattybogle

Tbf, my surgery is actually A* compared to many on here. I tend to just hold my ground on "I need an appointment before work". Nevermind the fact I work flexible hours from home. 😂

This is the second time it's happened to me whereby I feel like I've found my stable dose and feel great but then a few weeks later TSH has jumped up and my T's have fallen. 😒

Just when I think I've got a handle on things. 🙄

tattybogle profile image
tattybogle in reply to

lol.... i use that 'work' line too.. (been self employed for years :) )

"Just when you think you 're stable" ... confirms my pet theory that "it's all run by little blue pixies" ... i'll publish it one day .

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