How Should A Diagnosis Be Made?

What ME/CFS Is And What It Isn’t – How Should A Diagnosis Be Made?

ME/CFS is a clinically characteristic entity, that can be recognised as readily as many other conditions. As a considerable number of other illnesses have symptoms which overlap with ME/CFS, establishing a diagnosis will depend on a careful assessment of the symptoms. This may need to take place over the course of several consultations. The diagnostic process also requires various investigations to rule out other possible explanations, including but not limited to blood tests and a clinical examination (See both, the latter ICP is for Medical Practitioners Diagnosis Delay Harms Health – Early diagnosis why is it so important – A report from the M.E. Alliance – Dr Charles Shepherd International Consensus Primer for Medical Practitioners (ICP) (2012)).

The aim is to provide a positive diagnosis of ME/CFS, whereby a person is considered to have the characteristic features and pattern of the illness, as opposed to arriving at a diagnosis solely through the exclusion of other possible causes.

In general the patient should have symptoms (eg. post-exertional malaise (PEM)) that have persisted for more than 4-6 months in an adult and 3 months in a child (depending on the guidelines being followed). In addition the patient will be functioning at a much lower activity level than before the illness. At this point medical practitioners are advised to be cautiously optimistic and to provide realistic hope to the patient in that most people with ME/CFS do improve over time.

A tentative diagnosis is based on symptoms and evolves throughout the clinical assessment. Laboratory and other investigations confirm or refute the tentative diagnosis. Based on the patient’s history, risks, and symptoms, it is important to rule out other infectious diseases that could simulate the collective, complex pathophysiology of ME. New symptoms need to be investigated.

Symptom severity & impact (diagnosis includes a classification of symptom severity):

  • Mild: meet criteria and have a significant reduction in activity level;
  • Moderate: approximately 50% reduction in pre-illness activity level;
  • Severe: mostly housebound;
  • Very severe: mostly bed-bound and require assistance with daily functions. Those who are very severely affected are too ill to attend regular medical appointments.

It is also vital to recognise and manage any other illness that may be present in the same person (termed co-morbidities), as there may be more than one diagnosis. See related conditions such as Fibromyalgia (FM).

What we need to stress is that, ME/CFS is NOT depression or anxiety – although these may co-exist, as in other chronic conditions, and is entirely understandable. Diagnosis and management of depression and/or anxiety present along with ME/CFS will likely lead to a major decrease in total burden for the patient and should be sought immediately.

Neither is ME/CFS deconditioning as a result of reduced activity. Some people present with symptoms that superficially appear to be ME/CFS, but who actually have another explanation. Likewise it is important they receive a correct diagnosis.



Why early diagnosis is important

Doctors and diagnosis – or not

Diagnosis in acute onset ME/CFS

Diagnosis in gradual onset ME/CFS

The role of delayed diagnosis in the development of severe ME/CFS

Even further reading



Carruthers, B. M., et al. “Myalgic encephalomyelitis: International Consensus Criteria.” J Intern Med, 2011, 270(4): 327-338.

Carruthers, B. M. et al. “Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Clinical Working Case Definition, Diagnostic and Treatment Protocols.”  Journal of Chronic Fatigue Syndrome, 2003, 11(1): 7-36.

Fukuda, K., et al. “The chronic fatigue syndrome: a comprehensive approach to its definition and study. International Chronic Fatigue Syndrome Study Group.” Ann Intern Med, 1994, 121(12): 953-959.