Diagnosis of ME/CFS

Diagnosis of ME/CFS is based on a detailed history, physical examination and testing. An early diagnosis, with appropriate medical management and social support, may lead
to better outcomes.

History

Patients can assist the clinician by keeping a diary of symptoms, including activities and other factors that trigger a worsening of symptoms. It will also help to write down any factors that could be related to the onset of the illness.

There is often confusion between the symptom of chronic fatigue and the illness, Chronic Fatigue Syndrome, leading to misunderstanding over use of the word fatigue to describe symptoms of ME/CFS. Therefore it is important for diagnosis to explore the experiences that are labelled as fatigue, such as muscle weakness, inability to remain upright, cognitive difficulties. This will bring to light specific symptoms of ME/CFS, allowing it to be distinguished from other illnesses which have chronic fatigue as a symptom.

Post-exertional malaise (PEM), the worsening of all symptoms following minimal effort, is the cardinal symptom of ME/CFS. Because PEM is often delayed in onset, patients do not always recognise the connection between effort and both the decrease in function and escalation of symptoms a day or more later.

Physical Examination

Some common symptoms of ME/CFS will be evident on physical examination.

A feature of ME/CFS is instability in body systems and fluctuating severity of symptoms. Whilst some symptoms may be detected during an initial examination, others may become evident in subsequent visits.

People with ME/CFS may have pallor, tender lymph glands, localised tender points in muscles, painful joints without redness or swelling, resting tachycardia, low blood pressure or low body temperature. While orthostatic intolerance is best tested with a tilt table, there is an option for assessing it in the clinic.

Clinicians need to be aware that patients will only present for examination when their symptoms are mild enough for them to be able to attend. For people who are housebound by their ME/CFS, a home visit will be required.

The physical examination will also assist with identifying other conditions, which may exist alongside ME/CFS or might suggest an alternative diagnosis.

Testing

Currently there is no single test to confirm a diagnosis. Although routine blood tests often return normal results, further testing may show abnormalities that clearly identify markers of ME/CFS.

Clinicians may also undertake testing to rule out other conditions with similar symptoms, such as multiple sclerosis; and to identify treatable conditions that may be aggravating the ME/CFS, such as poor thyroid function or secondary depression.

Diagnostic Criteria in use in Australia

The ME/CFS Advisory Committee Report to the NHMRC Chief Executive Officer (30 April 2019) recommends the use of the Canadian Consensus Criteria (CCC), International Consensus Criteria (ICC) and the Paediatric Primer.

The CCC requires 6 months of unexplained fatigue before diagnosis. The ICC allows earlier diagnosis. The Paediatric Primer is designed to assist in diagnosis and management of young people.

South Australian clinical guidelines (2004) are based on the CCC.

The NHMRC now additionally recommends the UK's NICE Guidelines (2021) and the British Medical Journal's Best Practice Guideline (2024).

Additional considerations

It may help to have the diagnosis confirmed by a doctor who has extensive experience with ME/CFS patients.

While waiting for a firm diagnosis, it is important to avoid exacerbating ME/CFS symptoms.

An extensive lists of tests and treatments for ME/CFS and common co-morbid conditions are available from the U.S. ME/CFS Clinician Coalition.