Understanding Synacthen Test Results

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Hi there, recently had a short synacthen test and I am struggling to understand the results.

Morning baseline cortisol level of 166 nmol/l which they are saying is low. But 30 mins and 60 mins after the injection it went to 675 and 840.

Any advice appreciated

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  • Posted

    Hi, I know nothing about the results themselves, but I can comment from a statistical viewpoint and compare your results to mine (which were classed as normal).

    My cortisol level at 0 minutes = 690.7 nmol/L (it should be above 200 which is why they have said yours is low).

    At 30 minutes my cortisol level = 958.3. It should be 200 or more above the cortisol level at 0 minutes. Mine is 267.6 nmol/L (39%) higher than at 0 minutes, yours is 509 (306%) higher, which seems to be an over-reaction, however 675 is still only about two thirds of what mine was at 30 mins (958.3).

    At 60 minutes my cortisol level = 1097, whereas yours at 840 is only 77% of my level. They said all my results were normal.

    So you can see that all your results are lower and that you had a big spike at 30 mins. As to what this means and what action is required, I'm sorry but I have no idea.

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  • Posted

    Baseline is the level of cortisol you are producing normally and should peak at 9 am. Synachten simulates the hormone [ACTH] which provokes your adrenals to produce cortisol that you need if, for example, you were sick or involved in a car accident. I'm not a health professional but yours looks normal. So your adrenals are responding normally.

    Google for synachten test and look at the result from Leeds Teaching Hospitals Trust


    The next question may be - is your pituitary producing ACTH 'when required'.

    Emis Moderator comment: I have put the direct link suggested in above and a link to our article about this below. You can post direct links and they will be approved as long as they do not breach the rules. NHS links will always get approved unless we replace them with links to our own site on the same subject.


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    • Posted

      I'm not sure that I explained that very well!

      Your baseline is the level of cortisol that is normal for you in a [relatively] relaxed situation.

      When you get sick or have an accident, your pituitary sends out a hormone, ACTH, which stimulates your adrenal glands to produce cortisol to deal with it. Synacthen is synthetic ACTH and should have the same effect. Your second and third figures show that you did indeed get the expected boost of cortisol, so your adrenals are responding and working as they should.  This is good. You don't have Addisons or Cushings.

      But it takes you back to why your unstimulated (baseline) cortisol measure is low.  I expect that is what they will be investigating next.

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    • Posted

      Hi Ruadhraigh, Jackie here. Latest readings from another week in another hospital; baseline 51. After 30 mins 532. After 60 mins 615. Confusion and memory problems, eye problems blah blah blah. Stupid question but do these readings mean I have low cortisol? Thanks 😷


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    • Posted

      I have no idea. I'm not a medic. You have to ask your GP.

      What it does tell you is that your adrenals are responding as they should to the hormone prompt [dunno if too little, too much or just right - ask your GP]  which confirms that it really is all in your head biggrin  but you already knew that.

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