Low Cortisol - Synacthen Blood Test

[Health4I]

Hello,

With the above test (I am due to have next week) does it need to be taken first thing in the morning? I have previously had two standard blood tests at 9.00 am which has highlighted a low cortisol reading and so a follow-up synacthen test is now being taken by the GP practice. My appointment is mid-morning. I just assumed it would be taken at the same time as previously?

Also, does it make a difference if the second draw of blood is half an hour after the first rather than an hour? Just curious. Thanks in anticipation.

[Emyloulou]

My synacthen tests have always been performed 1st thing in the morning however your hospital may be different. It’s the increase in cortisol levels after the acth injection they are looking for so I would think any time of the day would be ok.

I had 3 blood draws, baseline cortisol and acth(should go straight to the labs on ice), 1 at 30 minutes and 1 at 60 minutes.

[humanbean]

For info on the Short Synacthen Test (SST), see this link and read pages 68 - 70.

imperialendo.co.uk/Bible201...

Note that quite a few SST tests are done without testing ACTH. This is very poor practice and means that some causes of poor cortisol levels can be missed. I would suggest that you phone the hospital a day or two before your test is to be done and ask if ACTH testing is included.

I wouldn't be happy, in your shoes, to have the SST test mid-morning. It should be done around 8am - 9am to get the most reliable and informative results. The Method section (top of page 69) in that link I gave above specifically says to start the test at 9am.

[humanbean in reply to humanbean]

Just to add to my post above...

There are three different types of adrenal insufficiency.

en.wikipedia.org/wiki/Adren...

If an ACTH test is not done, then as far as I know, only the first type can be checked for. With no ACTH test the second and third types cannot be found.

[humanbean in reply to humanbean]

Hidden is knowledgeable on the subject of cortisol.

[Barrister]

My first SST was done around 10 am so not as early as it could have been. However, even at that time my cortisol was non existent so I was diagnosed with Adrenal Insufficiency in less than 24 hours after that. The ACTH result takes quite a bit longer than that. Ideally the SST should be started at 8-9 am. You could try asking if they could change the time. And check at the same time that they will be doing an ACTH test as well.

Clemmie

[Health4I]

All responses noted and thanks. I guess it depends what type of insufficiency but if it transpires I do have this, is it generally medication that manages/resolves it?

[Hidden]

The SST can be done mid morning although as others have said best done first thing in the morning. Make sure they do the ACTH blood test (going onto ice) although as it's your GP surgery doing it - which is very unusual!! I doubt they will do the ACTH test which shows if the issue is with your pituitary gland so quite important. If you are shown to have adrenal insufficiency then you will be on replacement steroids for life. Primary is Addisons which is an autoimmune condition & the other is secondary where they either don't know the cause or because the pituitary gland is not producing ACTH to stimulate the adrenal glands to produce cortisol. Both are treated much the same & are a serious life threatening condition. Have a look at both the Pituitary Foundation website & the Addisons Disease website for more information.

[Health4I in reply to Hidden]

Thanks for responding. Can I confirm my understanding that the ACTH test is when they take a baseline blood, inject me with some 'potion' and then an hour later do a further blood test? I shall review the websites you refer to.

[Hidden]

Yes it's known as the short synacthen test (SST) You are injected with artificial ACTH, bloods are taken at the start (base level) & then at 30 mins & sometimes a gain at 60mins. They should take blood to test ACTH (hormone produced by the pituitary gland) at the start as this shows if the issues is with the pituitary gland. I'm very surprised a GP surgery is doing it though as it's usually done at the Endo department.