Medical Matters > Diagnosis: Buspirone Challenge Test

ME Essential Summer 2021


I didn’t think there was a blood test for ME. However, my doctor wants to arrange for me to have what is called a buspirone challenge test. If this test can be used to confirm a diagnosis of ME, why isn’t it being used more widely?


We don’t yet have a blood test that can identify an abnormality that is consistently and significantly abnormal and is also unique to ME/CFS. Research is going on, some of it funded by the ME Association Ramsay Research Fund, to try and find one but there is nothing on the horizon right now.

The buspirone challenge test was first assessed as a research-based investigation by my late friend and colleague in Glasgow, Professor Peter Behan. The results indicated that it can be used to distinguish ME/CFS from depression. And the abnormality which was identified, involving the function of a small gland in the brain called the hypothalamus, is important because this gland helps to control sleep, appetite, temperature and hormonal regulation – all of which are affected in ME/CFS.

However, the potential use as a diagnostic test for ME/CFS has never been properly pursued by other independent research groups and confirmed. It is not therefore recommended as a diagnostic test for ME/CFS by either NICE or the ME Association in our current state of knowledge. The value of this test in your individual situation is something that you clearly need to discuss with your doctor.

Research (please note that Professor Behan was using the term post-viral fatigue syndrome for ME/CFS at this time):

Abstract: The results suggest upregulation of hypothalamic 5-hydroxytryptamine receptors in patients with post-viral fatigue syndrome but not in those with primary depression. The buspirone challenge test may therefore be useful in distinguishing these two conditions. Larger studies are required to explore the potential value of drugs acting on central 5-hydroxytryptamine receptors in the treatment of patients with the post-viral fatigue syndrome.

Bhan P.O. et al. Possible upregulation of hypothalamic 5-hydroxytryptamine receptors in patients with postviral fatigue syndrome. | April 1992

More information

  • The ME Association has produced a free summary of the 2021 NICE Clinical Guideline for ME/CFS. The guideline recommends a series of blood tests to be used to help exclude other possible causes for symptoms before a diagnosis of ME/CFS is made. We suggest that you familiarise yourselves with the guideline's recommendations and discuss those that are most relevant with your GP, ME/CFS Specialist Service, and/or social care service (as appropriate).
  • We also have detailed booklets that can be downloaded from the website shop:
    • We explain why an early and accurate diagnosis is so important. We examine the core symptoms, the need to take into account a patient's clinical history, the need for clinical investigations and blood tests, and consider other explanations for persistent symptoms.
    • There is no diagnostic blood test for ME/CFS – but testing your blood is essential to rule out other illnesses that can cause similar symptoms. We take an in-depth look at what blood tests should be taken to ensure your diagnosis is correct.


Medical Matters is for information purposes only. The answers provided by Dr Shepherd and the ME Association’s other expert advisers should not be construed as medical advice. We recommend that any information you deem relevant is discussed with your GP as soon as possible. It is important to obtain advice from a GP who is in charge of your clinical care, who knows you well, and who can consider other likely causes for symptoms. Seek personalised medical advice whenever a new symptom arises, or an existing symptom worsens. Don't assume that new or worsened symptoms are a result of having ME/CFS.

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