Thyroid UK
84,329 members99,330 posts

How long is a piece of string (aka am I hyper or hypo)?

I have been on 125mcg t4 (alternating dose of 100/150) and 25mcg t3 (split dose 4x per day). I've recently been feeling pretty good on this dose - it took a while - and was even able to return to vigorous exercise a couple of weeks ago.

Last week I felt tense, had diarrhoea and was having a little trouble turning my brain off at night so I thought I might have gone a little hyper. I wanted to experiment with reducing my levo slightly to see if increased t3/reduced t4 works better for me (so far that has been progressively better than t4 alone or mostly t4) so I started taking 100mcg t4 per day and adding in 150 every few days (instead of every other day). (Doctor doesn't mind if I tweak things a little.) Still had symptoms, so have only been taking 100, but for the last few days my heart has been racing and I still have diarrhoea.

Pulse yesterday and today is around 80-85bpm and I have that shaky filled-with-dread feeling, which is oddly familiar as I used to have it all the time when I was hypo.

I've left a message for the doctor but it can take time to hear back. Is there any way to tell if I'm hyper or hypo? Or do I just need a blood test?

Last blood tests (4-6 weeks ago) were good but t3 close to the top end (I don't have the results to hand).

Annoying as I've been feeling so good lately.

Thanks in advance for your help folks.

11 Replies

If you're looking for short term reactions don't forget T3 is ~ 5X stronger than T4 -and faster acting, as it doesn't need converting..


Okay, I have read that t3 is "several times" or "three to four times" stronger than t4 but have not read that it is five times stronger. Just out of interest, where does that number come from? (Just to clarify, I'm not disputing the figure; I don't know a lot about t3 and my limited research didn't turn up the same results.)

If that's true, does it mean that if I was taking the equivalent of t4 alone I would be taking 250mcg per day (25 t3 x 5 + my current dose of 125 t4)? It's an interesting thought as it seems no matter how much t4 I was taking, it never relieved my symptoms like t3 does. In fact, there are specific symptoms (oedema in particular) which didn't respond at all to t4, even when my t4 and t3 bloods were at the top of the range.


I have looked in my notes for a ratio but it must have been on a page that crashed before I could copy. However, I did use the circa sign~ and maybe, should have said up to 5x.

3 or 4 x is commonly quoted, I know, but two factors intervene here.

One is the the relative strength of T3 in supply [known to vary] and the other is conversion efficiency in different people, which also gives an 'apparent' strength deviation during use.

I have notes on these factors from Dr Lowe and Moggies post on here a while back.

There seems to be very little hard evidence on strength comparisons due to lack of research, as you note.

Lets' say that T3 can be up to 5 times T4 effect on various estimates and that will be modified, usually down, by individual reactions including conversion efficiency.

Some sensitive to T3 may find different results up or down, as it doesn't seem to be a panacea for all -assuming they can even get it.

So, on the estimates discussed, your equivalent dose may well be 250mcg- but that is acedemic to a degree, as the effect applies only to you -as does the 'wellness' you feel.

Useful for your ongoing treatment changes but not correlating with other due to the variables.

More research could clarify this -but would still not predict a standard regime of treatment for all.

[as with TSH, being of limited use in truth- but T3 'seen as' hard to use and still treated warily by most, defaulting in the opposite direction]

This why T4 gets given as standard, in my view, as UAT symptoms can be ignored using 'tramline' TSH levels- but T3 side effects not ignored so readily.


Thank you very much for that explanation. Can I conclude that t4 is just the pill more doctors feel comfortable prescribing and have the impression they know more about? So they like to talk in terms of certainties about t4 but in terms of uncertainties about t3 because there is an illusion that more is 'known' about the former than the latter? T4 has been more medically quantified than t3 - ?

There is also the idea that t3 (or potentially being more easily overtreated with t3 maybe - ?) has more potential to cause heart problems, but is this true or also just a wary assumption? Because being hypo causes heart problems too but I never knew a doctor to be too worried about it.

I feel so lucky that my gp was willing to prescribe because I don't know how long I would have lingered (with my 'perfect' bloods, high in both t3 and t4 ranges) feeling swollen, wooly-headed, anxious, still constipated and so very very tired all the time. Now for the first time in five years I'm back to running twice a day as opposed to avoiding movement at all costs (the things I would do to avoid having to get up from the sofa or walk up the stairs...).

Thanks again for your reply.


Thanks for that. Okay, do you mean are my symptoms short-lived shortly after I've taken my t3? The funny thing is that this isn't a short-term thing as soon as I've taken my meds. It seems to be when they would be wearing off/next dose due. Each dose is only approx 6.25mcg, so I should be okay - ? Took a tiny dose (the smallest 'quarter' of a tablet) at 6:15am but felt okay until I had the runs/anxiety around 9:30/10.

I thought about caffeine - ? But I only had two cups of tea today. Yesterday anxiety was worst in the afternoon, a long time after any caffeine. And when I'm well-medicated, caffeine is much less of a problem than it was when I was hypo. Symptoms are so similar so hard to tell apart from each other.

I had no problems when taking t3 all in one dose, but I find my energy is a bit longer-lasting on the split dose. And I can always tell when it's time for a dose as my eyes want to close!


Have you tried taking your temperature.If it is below 98.4 [37]you should still be hyPo unless you have a fever of course.hope this helps


Thanks. Good idea. I'm at my mum's and she's away on hols, so now I just have to figure out where she keeps a thermometer... :-)


It's possible to get hyper symptoms when taking T3 or a combination of T3 and T4 if you have low iron or cortisol issues. This website is very helpful:


Thanks. Will have a look.


I definitely have adrenal issues so perhaps that is an issue. I'm usually anaemic too, though I haven't been tested lately. I got a bit slack over the summer so I will return to supplements.


Just wanted to update you kind people. I upped my t4 dose again and the anxiety completely went so I guess I was not hyper, but I still have some hyper symptoms (the diarrhoea is particularly of concern as I can think of no other reason for it and it persists over time). In any case, it feels like a miracle that I'm running again and although I wouldn't say I was bursting with energy, I'm up and busy for much of the day, I no longer have that catatonic feeling of just struggling to stay conscious and best of all, the anxiety that used to plague me is under control. Result!


You may also like...