How is chronic fatigue syndrome diagnosed?

There are no laboratory or imaging tests that can diagnose chronic fatigue syndrome. The diagnosis of chronic fatigue syndrome is based on a medical history and physical examination. Doctors use specific criteria to diagnose the condition. Lab tests are used to rule out other medical conditions that may be causing fatigue and other symptoms. In general, the results of routine lab testing are normal in people who have only chronic fatigue syndrome. Doctors carefully question patients about their symptoms, any other illnesses they have had, and medications they are taking. They also conduct a physical examination, neurological examination, and laboratory tests to identify any underlying disorders or other diseases that cause fatigue. In the United States, many doctors use the CDC case definition to determine if a patient has chronic fatigue syndrome.

To be diagnosed with chronic fatigue syndrome, patients must meet both of the following criteria: Unexplained continuing or recurring chronic fatigue for at least six months that is of new or definite onset, is not the result of ongoing exertion, and is not mainly relieved by rest, and causes occupational, educational, social, or personal activities to be greatly reduced. Four or more of the following symptoms: loss of short-term memory or ability to concentrate; sore throat; tender lymph nodes; muscle pain; multi-joint pain without swelling or redness; headaches of a new type, pattern, or severity; unrefreshing sleep; and post-exertional malaise (a vague feeling of discomfort or tiredness following exercise or other physical or mental activity) lasting more than 24 hours. These symptoms must have continued or recurred during six or more consecutive months of illness and must not have started before the fatigue began.

More information on chronic fatigue syndrome (CFS)