The Canadian ME/CFS Clinical Case Definition and Guidelines for Medical Practitioners (Overview) provides a comprehensive breakdown of the symptoms, diagnosis and management of ME/CFS. While aimed at medical practitioners, it is also of great value to people who have ME/CFS, assisting with a greater understanding of the condition.

Diagnosis of ME/CFS

Diagnosis is based on:

• Physical examination;
• The type, pattern and severity of symptoms;
• The history and length of illness; and
• Laboratory and other tests.

A medical practitioner will carry out routine laboratory tests and, following assessment of the person's symptoms, case history, physical examination and his/her test results, may request a number of additional laboratory tests and investigative procedures, depending on the individual's specific illness profile.

Although there is no specific test available yet to diagnose ME/CFS, routine laboratory and other investigations are important to eliminate other diseases that have symptoms in common with ME/CFS. Abnormalities may be found in a number of non-routine tests and, in some circumstances, may be of diagnostic assistance. Some non-routine tests are showing promise as potential diagnostic tools.

A diagnosis of ME/CFS will involve a number of visits to the diagnosing practitioner over a period of time. The diagnosing practitioner is usually able to make the diagnosis, although in individual cases the practitioner may refer the person to a specialist.

For a positive diagnosis of ME/CFS to be made, symptoms need to correspond with a Case Definition of ME/CFS and to have been present for at least six months, although a diagnosis may be made after three for children. Excluding other illnesses is an important part of the diagnostic process.

It is not uncommon for people with ME/CFS to consult a number of doctors before receiving a diagnosis of ME/CFS because some practitioners are unfamiliar with ME/CFS. In these circumstances a clear diagnosis can be a relief for the person with ME/CFS as it removes the uncertainty and allows the person to focus on treatment and illness management.

For more information on the diagnostic procedure for ME/CFS, refer to the following pages of the Canadian Guidelines (Overview):

• Clinical evaluation of ME/CFS, pages 7-8;
• Routine tests, pages 8-9; and
  
• Non-routine tests for abnormalities in ME/CFS, page 18.