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Synacthen test results - any idea what they mean???

Here's hoping there is a budding endocrinologist on the boards who can help me understand my sons Synacthen test result.

Was told they looked ok but think they were only looking for complete failure and was wondering if perhaps there was some sort of supression.

Am a little confused as the info I found on the web says you should have the test done in the morning and with no Pred in system but my son's was done in the afternoon (3pm) and was on 20mg alternate day pred.

so here goes :-

before synacthen 131

1/2 hour 213

45 mins 192

highest reading at about 15 mins was 356

Hope someone can shed some light on it as my research is very confusing.

3 Replies

hi koolkat

Those results seem ok to be honest. You may need steroid cover if you get a bad infection or have any operations etc but for normal daily activities etc you should be fine.

Synacthen tests are to establish if you have adrenal supression which would be very low pre and post results for costisol. When i had mine my pre was 9 and my post was 15 therefore i was diagnosed hypoadrenal im on daily hydrocortisone as steroid replacement as my body no longer produces costisol which is essential to maintain life and metabolism etc.

When i was diagnosed i did have some symptoms but they were not at adrenal crisis level so your levels do have to be low or your body has to under severe stress before you notice there is a problem. For you you should be fine without any replacement as your body is obviously still producing costisol. They should probably keep an eye on you just in case things change but please dont worry about it. They will or should discuss steroid cover with you for times when your body is stressed ie during infections illnesses or before and after any operations.

Hope this helps and please feel free to pm me if i can help further.

Take care lv kat Xx


Hiya Kit Kat and thanks for taking the time to reply to my post.

Your values threw me a bit as they seemed ridiculously low but after looking again found there are 2 scales in which the responses are measured.

Adrenal hypofunction is suspected if basal cortisol levels are <225 (8.2) and cortisol levels after 30 min are <550 (20) and/or there is <200 (7.2) increment from basal to peak cortisol levels.

If my rather poor maths skills are correct my levels on your scale would be about 4.7 pre synacthen, 7.8 after 30 mins and a maximum cortisol level of 13 (after 15 mins)

This would then meet 2 of the criteria (basal and peak) but is out of range for increment as this would be 8.3 and not less than 7.2

So am still confused - as according to everything I have read basal cortisol should be done in morning and you shouldn't be taking Pred at the time as it can affect the cortisol levels. Looks as though I am going to have to pin down cons and ask him what it all means.


sorry for the confusion koolkat but im on the same system as you. My values were extremely low the endocrinoloist had never seen them that low before. Was told am levels should be 400-600 but mine was 9. And pm values should be more than 200 mine was still low. Post acth they expect the levels to rise over 60mins mine did not rise much but they diagnose usually if levels are less than 200 here but they dont treat if there is a rise in costisol as there is still adrenal function. They only treat if your values do not rise and are on the low end normally.

Hope i made things clearer but yes i am on the same system i just had very low levels and was acutely unwell at the time hence they treated. Even on treatment my levels are still just slightly sub normal at 250 in the am and 100 in the evening. It can result in you feeling very lethargic but i have got used to running on low levels now i think- it only ever causes problems as i said before if im unwell or having any minor operations etc.

Hope this helps. They may choose to treat you with some low dose steroid replacement but if you were in my area they wouldn't routinely as the levels are not low enough. As the criteria indicates that the rise in costisol should be relivitely minimal and yours did rise over that level they will probably not treat you and just keep an eye on your levels. Its a very strict criteria as once they start replacement therapy it can stop the adrenals working properly so as there is still function they may want to see if time improves things.

Did you take pred before the basal level ie the first blood test?

Pred is a synthetic steroid and thus will falsly increase your levels giving an inaccurate result. Tho im not sure it would effect the increment amount or not!

And was the test done first thing ie 9am-10am is the best time??

These tests should be done when levels are at there highest which is at 9-10am unless you routinely work night shifts. If you routinely work nights and never get up for day shifts your body will have adjusted so your highest level will then be at whatever time you normally wake up. Shifts can mess up your levels so that could be a prob if you do do shifts!

Please feel free to pm me if i can help any further as i do know a lot about endocrinology after spending a lot of my career doing these tests and analysing results.

Please take care and if you are getting symptoms talk to the endo team they're very good usually. Take care lv kat Xx


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