During my on-going quest to establish what the hell is causing me to feel so crap, so often, I managed to secure a '2nd opinion' from another NHS endo. The appointment was this morning and pre appointment I made sure she received ALL the info on what's been going on over the past 3/4 years. She's still adamant that my thyroid is perfectly healthy, and has instead focussed on my pituitary, at my request. She took an enormous amount of blood tests today and another short synacthen but this time with an ACTH test. About 15 mins after the injection I started to feel more alert (barely functioning when I arrived), within an hour after the injection I was pumping on all cylinders, I felt FANTASTIC - 4 years of fatigue seemed to peel away. I continued to feel fantastic the entire day, I still feel pretty good at 7.30pm. I know this will wear off and tomorrow I'll be back to barely functioning, but, what does this prove? Do I need ACTH meds or cortisol? Or something else? Any help gratefully received.
2nd Short Synacthen Test Today - amazing post t... - Thyroid UK
2nd Short Synacthen Test Today - amazing post treatment
As I understand it, you need cortisol.
ATCH is a pituitary hormone that stimulates the adrenals to make cortisol. If the pituitary isn't functioning correctly, and not making enough ATCH to stimulate the adrenals to make enough cortisol, then you are going to have low cortisol symptoms. This test shows that the adrenals are function well, when they get the right stimulus. And, that goes to show that it's the pituitary that is not functioning correctly. So, you were right to insist on pituitary investigation. I just hope the doctor understands the results, because it seems to me that they don't always. 
Thank you greygoose, yes, I think I may be barking up the right tree with the pituitary, it just remains to be seen if it's pituitary or hypothalamus and to be honest, I don't have that much confidence in my endo, however, she does seem amenable to helping me work through this, which is something.
I don't honestly think it makes much difference whether it's the pituitary or the hypothalamuse, because either way, there's not much you can do about it. All that can be done is replace the missing hormone, like T4 and T3, and cortisol. The important thing is to know that it isn't they thyroid or the adrenals at fault.
I had exactly the same reaction after my 2nd Synacthen test. I could barely walk into the hospital but after the test and waiting around for my results, I suddenly felt fabulous. I even came home and mowed the lawn. That was definitely something I could not do. The morning after though I was back to my heavy, lack of energy self and struggling. Have you had your T3 tested? I eventually found out after going private only that I’m a poor converter of Levothyroxine T4 to active T3. It was only when I was put on a trial of t3 combined with Levothyroxine that my health improved dramatically. My Synacthen tests both came back normal. It’s wasn’t my adrenals at all, it was all down to my lack of T3. I was only converting 8% of Levothyroxine T4 to active T3. I also did the DIO2 gene test through Regenerus Laboratories which came back positive. This meaning I struggle to convert Levothyroxine to T3. Oh boy what a difference T3 had positively made to my life. If you haven’t checked your T3 and DIO2 and your Synacthen is normal I’d check them.
Thank you McPammy. Yes, that's exactly how it feels - heaving and foggy and flat, but after that shot, my god, I was like a different woman. There's now no doubt in my mind that low cortisol, even if it's 'within NHS range' has a part to play in this jigsaw. I now need to figure out if it's central or tertiary hypo because my thyroid levels are not ok, despite once again, every endo saying I'm just 'low normal'. I'd like to see them functioning in their job on these levels, even just for a day.
Re. T3 levels, I started a trial of 50 levo around May, I continued for 6 weeks and tested again, my tsh was suppressed and both T4/T3 had increased. I remember someone on here commenting that I seemed to convert well so I don't think conversion is a problem. I tried to increase to 75 levo and that's when the problems started, I began to feel really unwell - very weak and dizzy and I'm convinced it's because I have secondary or tertiary hypo and you must treat the adrenals before adding thyroid hormone into the mix, if this is the case.
I'm essentially a living Petri dish with daily experiments, but I now feel I'm getting a little closer.
Sounds as though it could be adrenals. Your Synacthen test will determine that for sure. My 9am cortisol was very low and below range 68 (155-650). I was convinced it was my adrenals. But it was T3 in my case. Once I started T3 within 4 weeks my cortisol shot up to 450 from being below range for months. Infact all sorts of things in my body suddenly worked properly. My eye sight, blood pressure, heart rate, metabolic rate, skin felt good it had been very dry, I could walk normally instead of clinging onto walls and door frames. The list could continue 🙄. And I lost the 4st I’d piled on. I do hope you find your issue and soon I know how horrible life can be waiting to try and sort it out.
As this suggest pituitary issues, maybe have a look here:
The Pituitary Foundation
Who we are
It is estimated that there are approximately 70,000 people with a pituitary condition in the United Kingdom. To meet the need for information and support The Pituitary Foundation was set up in 1994 and was subsequently registered as a charity in September 1996.
The Pituitary Foundation is a national support and information organisation for pituitary patients, their families, friends and carers. We are the UK's leading charity providing support to people affected by disorders of the pituitary gland such as acromegaly, Cushing's, prolactinoma, diabetes insipidus and hypopituitarism.
The Pituitary Foundation operates throughout the UK and Republic of Ireland. We are a membership organisation and have in the region of 2,300 subscribed members and we support thousands of people affected by pituitary conditions each year. We are a relatively small charity, with ten members of staff and supporting our work we have a team of 140 volunteers across the country.
How each hormone replacement medication affects other hormone levels
pituitary.org.uk/informatio... replacement-medication/
There are many possible causes of Adrenal Insufficiency. This brief description from wikipedia may be helpful :
en.wikipedia.org/wiki/Adren...
Types
There are three major types of adrenal insufficiency.
Primary adrenal insufficiency is due to impairment of the adrenal glands.
80% are due to an autoimmune disease called Addison's disease or autoimmune adrenalitis.
One subtype is called idiopathic, meaning of unknown cause.
It can also be due to congenital adrenal hyperplasia or an adenoma (tumor) of the adrenal gland.
Other causes include; Infections (TB, CMV, histoplasmosis, paracoccidioidomycosis), vascular (hemorrhage from sepsis, adrenal vein thrombosis, HIT), deposition disease (hemochromatosis, amyloidosis, sarcoidosis), drugs (azole anti-fungals, etomidate (even one dose), rifampin, anticonvulsants)
Secondary adrenal insufficiency is caused by impairment of the pituitary gland or hypothalamus.[8] Its principal causes include pituitary adenoma (which can suppress production of adrenocorticotropic hormone (ACTH) and lead to adrenal deficiency unless the endogenous hormones are replaced; secondary adrenal insufficiency can be caused by steroids, inhaled steroids such as Flovent; and Sheehan's syndrome, which is associated with impairment of only the pituitary gland.
Tertiary adrenal insufficiency is due to hypothalamic disease and a decrease in the release of corticotropin releasing hormone (CRH).[9] Causes can include brain tumors and sudden withdrawal from long-term exogenous steroid use (which is the most common cause overall).[10]
...
If you read pages 68 - 70 in this link:
imperialendo.co.uk/Bible201...
it describes how the Short Synacthen Test (SST) ought to be carried out. But from what I've read on this forum, it is uncommon for the SST to be performed in its entirety, and ACTH is rarely measured. This effectively means that the basic SST test is only be used to diagnose Primary Adrenal Insufficiency. If someone has Secondary or Tertiary Adrenal Insufficiency the problem will be missed and the patient will be told their adrenal glands are fine, but a poorly functioning pituitary or hypothalamus will be missed.
I assume this problem is due to penny pinching and a belief that Secondary or Tertiary Insufficiency are both so rare that that nobody can ever have it. It's absolutely nuts.
What you (probably) got injected with was a drug called Tetracosactide
This link go.drugbank.com/drugs/DB01284 tells you that tetracosactide is a synthetic form of ACTH.
So, I would suggest that you might have felt great because you don't normally have enough ACTH, which means that your adrenal glands might not be getting sufficient stimulation to do their job, which is to produce several hormones including cortisol.
Having been injected with a synthetic version of ACTH suddenly your adrenal glands worked for a while. Your adrenal glands might not even be damaged. It might be your pituitary that is the problem in not producing enough ACTH to prod the adrenal glands into doing their job, or your hypothalamus that is the problem because it doesn't produce enough Corticotropin-releasing hormone (CRH) to stimulate the pituitary.
The adrenal glands produce multiple hormones. I'm not sure which ones are produced as a result of stimulation by ACTH but this link might tell you (I haven't read it).
en.wikipedia.org/wiki/Adren...
Good luck.
Thank you Humanbean - I've had a quick look at ACTH on wiki and it seems it's only cortisol that it stimulates, in which case the evidence from yesterday was very clear. Thank you for the info, I'll have a good read through.
I insisted on a ACTH test yesterday, the previous SST was without and proved only that my adrenals work when stimulated, not whether they are stimulated enough naturally. And yes, I think it's a combination of penny pinching and lack of knowledge. My endos are based in the diabetes department and both have been avid computer searchers whenever I ask a question. Really not good enough, but it's a start, and I won't give up.
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