Thyroid UK

Synacthen test - felt better

I am hypothyroid, on 75 mcg Levothyroxine, I feel less bad on this than before I was finally put on it once my TSH reached 10.30.

Before this was finally dealt with I had a short synacthen test three years ago, which made me feel good for the three days following it - loads of energy, motivation etc. managed to get a full days effort for these days, this was not the result that I expected, and due to the cortisol results being 'normal' no further action was taken.

Does anyone know of any reason that the short synacthen test would result in feeling so much better for those three days

I cannot find anyone that can explain why I felt better for this short time.

Ideally I want to replicate how I felt for those three days somehow.

Does anyone have any ideas?

8 Replies


Strange you should say that I always feel better after iodine injection for thyroid nuclear scan and when I had a short synthacen test.

I had a dangerously low cortisol blood result and 1.6% iodine uptake... both short synthacen and uptake were put down as normal 😖. Mmm...weird.

Doesn't the synthacen test involve a dose of cortisol, rested and repeated (measured between) if I remember? Maybe wrong. If so does it boost cortisol if low???



Need more info really, but first I'd say if you felt better after the test and the give you cortisol first then common sense says you need some cortisol daily, as for more info needed, your thyroid levels, need more than the TSH Level, you need your FT4 and FT3 levels checked too. Plus add I these nutrients for testing, Vit D, B12, B9, iron/ferretin, Zinc,(for adrenals) Vit A, Magnesium, (for thyroid hormone conversion) Low B12 and Zinc and an MCV over 86 are red flags for low stomach acid, and needs correcting for nutrient absorption.

Hope that helps...


During the test you would have been injected with a synthetic form of ACTH

probably Tetracosactide

The short synacthen test, also known as the ACTH stimulation test

would have increased your levels of cortisol (and possibly aldosterone as well, according to wikipedia).

Beyond that, I don't know anything. But I can make a very, very obvious guess and say that the extra cortisol made you feel better.

You could try buying adrenal supplements - they are easily sourced on sites like Amazon. I know there are various brands of these, and they aren't all the same. I've never needed adrenal supplements though so I can't be more specific than that. Hopefully someone else can help.


It might mean that you have a slight pituitary problem so you are just not making enough or too much ACTH - therefore cortisol level is wrong (although you'll test normal as you can make cortisol when stimulated by enough ACTH or ACTH is suppressed if given Dexa - or something like that). The NHS only recognises full blown Addisons or Cushings and they won't treat if you are anywhere in range. Do you have the ACTH and Cortisol results of the test?


Thank you all for the replies, I was thinking along the same lines as Angel_ , I can try to get the results, do not have them at the moment. I just want to replicate the effects of the synacthen and feel normal, which just does not feel like too much to ask, it is just hard to get the NHS to appreciate there is a problem, let alone identifying it and getting it sorted.

I really do not feel like they are invested in making me well, and only I truly know how I feel now and how far from normal that is.

I am unsure as to what avenue to take once I have results, and I do not remember them doing an ACTH test.


The ACTH stimulation test is just another name for the short synacthen test (SST).

For the official method of doing the SST, see this link :

find the table of contents, and then click on "Short Synacthen Test". It is described on pages 66 - 68.


Same thing happened to me and I felt terrific for about 3 days.

I would guess it was the increase in cortisol once the adrenals had been stimulated which is precisely what the test does.

My first result was just in range but when stimulated at 60 minutes the result more than quadrupled!! It's meant to double.

I would suggest that my adrenals were so grateful for the stimulation that they had a party.

I have always believed that I have some secondary adrenal insufficiency as I am also secondary hypothyroid.

Doctor said I passed the test!!!


My face was flushed after test, had an urgency to pee, and was very sleepy a few hours later. And the days following I felt like crap. Like this horrible impending doom feeling and I just not getting better but worse. I am still waiting for the saliva test but now not sure if it's adrenal isufficiency or cushings?? I had a severe adrenal crisis 3 months ago and I just cannot figure this out. 😢


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