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Diagnosing CFS: Textual Explanation

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The following summary is the procedure recommended by a panel of chronic fatigue syndrome (CFS) experts for clinically evaluating and classifying chronic fatigue. It is designed to help you better understand the process that your physician used (or will use) to reach (or exclude) a diagnosis of chronic fatigue syndrome.

Step One:

Your doctor will obtain a detailed medical history from you by asking a series of questions. This will be followed by a complete examination.

Step Two:

Your doctor will conduct a mental status examination. Usually, this will entail just a short discussion in the office or a brief oral test.

Step Three:

A standard series of laboratory tests will be performed on blood and urine specimens to help identify alternative causes of fatigue.

Step Four:

If your initial test results suggest an alternative explanation for your fatigue, additional laboratory testing may be required to confirm a diagnosis. If no cause for chronic fatigue is identified at this point, your doctor will proceed to the next step.

Step Five:

A patient will be classified as having CFS if he or she meets the following two criteria:

  1. Unexplained fatigue that is not due to ongoing exertion, is not relieved by rest, and results in a substantial rEducation in previous levels of activity, and...
  2. If four or more of the following symptoms are concurrently present for six months or more:
    • impaired memory or concentration
    • sore throat
    • tender cervical or axillary lymph nodes
    • muscle pain
    • multi-joint pain
    • new headaches
    • unrefreshing sleep
    • post-exertional malaise


If a patient's fatigue is not severe enough, or if the symptom criteria for CFS are not met, he or she will be classified as having idiopathic(defined) chronic fatigue.

Placing various fatigued patients into specific categories provides scientists with a convenient means for comparing CFS patients with other forms of unexplained fatigue, thus enabling them to search more effectively for any clinical markers that may be unique to CFS.

Page last modified on May 3, 2006

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