Medical Matters > Test: Synacthen

ME Essential Spring 2023


A blood test has shown that I have a low level of the hormone cortisol. As a result I am now being referred to hospital to have a synacthen test to assess my adrenal gland function. As this test involves the use of a drug that stimulates steroid production is it likely to cause any problems for someone with ME/CFS? Or could the use of a steroid be a way of treating ME/CFS?


Output of cortisol from the adrenal glands, which sit above the kidneys, is under the control of two glands in the brain called the hypothalamus and the pituitary.

The synacthen test involves the use of a chemical copy of adrenocorticotropic hormone (ACTH) – a pituitary gland hormone that stimulates the two adrenal glands to produce cortisol. The test therefore assesses the integrity of the whole hypothalamic-pituitary-adrenal axis (HPA), along with the output of cortisol from the adrenal glands.

The main reason for arranging this test is to make sure that you do not have Addison’s disease. This a condition that causes a number of symptoms that also occur in ME/CFS – including debilitating fatigue, low blood pressure, nausea, joint and muscle pain. In Addison’s disease there is serious and potentially life-threatening reduction in the output of cortisol. So treatment normally involves life long treatment with steroids.

A large number of research studies have now confirmed that there is a down-regulation of the HPA in ME/CFS, along with a small reduction in cortisol output in some cases. So a short lived boost to cortisol production could, in theory, account for occasional anecdotal reports of people feeling a bit better after undergoing this test. At the same time I do not have any reports from people who have had adverse effects following this test. So the test should not cause any problems.

Several small clinical trials involving low doses of cortisone (in the form of hydrocortisone) have been carried out to assess the use of this drug as a possible treatment for ME/CFS. The results indicate that any benefits are only minimal and there is a significant risk of causing further suppression to the natural integrity of the HPA. So this is not a form of treatment that is normally recommended.

A summary of research into this aspect of ME/CFS, along with results from clinical trials involving cortisone treatment, can be found in the ME Association's ME/CFS/PVFS Clinical & Research Guide 2022 Edition (also known as the ‘purple book')

See Also: Addison's Disease


Information provided by The ME Association should not be construed as medical advice. Don't assume any new or worsened symptoms are simply the result of having ME/CFS or Long Covid. We recommend that any information you deem relevant is discussed with your NHS GP as soon as possible. It is important that you seek personalised medical advice from the GP who is in charge of your care and who knows you well.

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