Hello,
Does anyone know how long it takes for T4 to build to its highest point in the blood, as it’s a storage hormone im assuming there is a point at which it reaches peak concentrations after which it can’t go higher without a further dose increase.
That's why we advise 6 - 8 weeks for a blood test as it can take that length of time for the full effects of a dose change to become apparent. Having said that there are folks on here who don't feel the full effects of a dose change until 12 weeks or more. Again we are all a bit different and only by knowing your own body will you know how long it takes for the effects of an increase to be fully felt.
Now ft4 can rise without a dose increase. When vitamins are improved for example or when a gut is heal and absorption improved then folks may get an increase in ft4 from the same dose of levo.
hmmmm… I thought that it was 6-8 weeks but I start to feel the sensations of the dose reaching a height after 9 days, always after an increase so I wonder why I feel it so soon…
The problem isn't that most of the effect doesn't occur quite soon. It does.
It is that the levels that are tested, especially TSH, take 6 to 8 weeks to stabilise. But even then, changes can continue for much longer.
If we could be tested every day, we would see small changes. And be able to see when things stop changing significantly. None of us has that option so we make sure we leave it long enough to be fairly sure before re-testing.
yes I see. Maybe I should have worded my question differently as I’m not asking bloods vs symptoms, I’m more interested in why on day 9 after raising ndt I get signs of stimulation (BBT, HR, tinnitus etc.) I wondered if it’s because T4 has built to a certain point, and then I wondered if it would continue to build even higher thereafter. I hope I’m making some kind of sense.
That's interesting helvella I was wondering the same.I am lucky enough to live in Greece where I can walk in to the local microbiology lab and get tested instantly and relatively cheaply. I am self-medicating now and after a recent increase (4weeks ago) from 25mcg to 50mcg I noticed a lot of improvements after a week or so, but my symptoms have returned now. I want to increase again or add in T3 but thought I had to wait for 6 weeks before testing... what would you do in my situation?
Because we don't see people testing frequently, we don't have much hard evidence of how levels change over shorter periods.
We tend to see the odd person who had, say, a private test, followed by an NHS test days or a week or two later. Fairly random gaps in time. And often not getting FT4 and FT3 done on both occasions.
TSH, in particular, can take a long time to stabilise. And we see this being a matter of months or years (or never) after long-term very low TSH. Also, I strongly suspect, those who have had a very high TSH see that rise again much faster and higher if they are under-dosed, than you might have expected.
And it is quite feasible that FT4, say, could go up quite quickly, then fall back a bit. Or some other pattern. It isn't always going to be a simple smooth curve.
What I keep hoping for is a super-simple, super-cheap test. Even if accuracy isn't as good - it could indicate which way we are going. (Reliability is vital, of course.) So that we could all see the curve.
If you are willing and able to pay, carry on. Just be very aware that they were done "too soon" when you look back on them in future.
Kriticat and Relentlessearch. from a purely 'symptom' point of view, (not bloods), i would say that approx 10 days is when i've often felt the difference from small increases or decreases in levo. (there are subtle effects before that , but 10 days is when i really know about it).
However , for the first 5 weeks of any change , (particularly a decrease), i've found how i feel will be changing every week , with all sorts of apparently random things being an issue for a few days or a week, ie. to cold/ too hot , constipation, unusual headache , feeling wiped out/ more energetic at random , appetite and sleep changes, weird dreams etc etc .... but from week 5 onwards things seem to stabilise and from that point on i can get a fairly good idea of whether it was the right move or not.. ie. if the dose change is going to be an improvement on previous dose , then from week 5 onwards things will very slowly improve , (and keep improving gradually for the next couple of months ) ... but if the dose change was the wrong move , then from week 5 onwards things will still be getting worse not better .
So my personal rule of thumb is now to pretty much ignore how i feel for the first 5 weeks, just make a note of it each week , and then make my mind up from week 6 ... if i'm not sure , or if i think i might be improving a bit , then i'll wait a few weeks longer to test , to see if improvement continues , ie test @ 8/12 weeks . but if i feel i'm still getting worse at 6 weeks, then i'll test @6 weeks .
I'm fairly sure that making any further changes to dose (based on symptoms) before this point is nearly always a mistake.
If id' been asked during the first 5 weeks of my last dose reduction, i'd have been absolutely adamant that it was too low and needed to be put back up ,,, but i'm glad i stuck it out for a bit longer , because over the next few months i improved a lot and found the new dose much better overall than previous one .
I've experimented with increases too ,and found similar .
I see it as a bit like a pendulum , when you knock it (change dose ) , symptoms can initially moves too far in the opposite direction , but as it settles you can tell gradually see where it's pointing ....... so even very small decreases can sometimes bring symptoms of under-medication for the first few weeks , which then improve as body adjusts .... and increases can also feel a bit 'all over the place' for a few weeks , then gradually bring more sustained improvements if it was the right move.
Hope that helps .
I think you are right to point out symptoms as key.
When discussing B12, one sign/symptom of low B12 is macrocytosis - large red blood cells (RBC). If the person starts taking (or injecting) sufficient B12, their blood serum B12 shoots up.
New RBC rapidly start to be "normal" size. But the turnover time for RBC is around 120 days.
However much B12 is taken, the 120 days turnover remains much the same. So it always takes about that long for the full impact of B12 on RBC to be reached.
That is only looking at a single effect of B12, of course.
The reason for mentioning it is to highlight that the impact of thyroid hormone will vary from one type of cell/tissue/bodily system to another. Taking minutes for some, months and years for others. And the difference between an increase but still under-dosed and an increase that gets you to the right dose, or even over-dosed, is significant.
thank you so much for sharing, that’s really helpful 🙏🏻☺️
So is this the same as T3?
I don’t take NDT either BUT it’s 7 days for me on the recent dose increase. I reduced my new increase from 125mcg to 112.5 alternating with 100mcg until I felt comfortable, because I could not live with the symptoms. I then took a blood test 33 days after the initial increase (for my upcoming endo appointment) and my T4 had jumped to 126% from 64% at the last blood test on the old dosage 100mcg. Who would have thought quite such a sizeable jump could happen with an average increase less than 12.5mcg? So, like everything thyroid it looks like everyone is truly individual and probably different again within every change of dose. This is the tweaking necessary to find our ‘sweet spot’? Totally ignored off course by the powers that be. Thankfully we have the forum.
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