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Chronic Fatigue Syndrome

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At this time, there is no blood test, imaging scan, or other test to diagnose chronic fatigue syndrome. The syndrome is diagnosed by excluding other possible causes. This typically involves:

  • Documenting the patient's medical history
  • Performing a thorough medical examination
  • Conducting cognitive function tests
  • Ruling out other conditions that may be causing or worsening the fatigue (and/or identifying and treating those that can be treated)
  • Fulfilling the Centers for Disease Control and Prevention (CDC) or the National Academy of Medicine criteria for the definition of CFS
  • Monitoring the patient over time to see if other underlying conditions arise

Patients may get a classification of unknown or idiopathic chronic fatigue if they do not meet the CDC's or National Academy of Medicine's symptom criteria for CFS or do not exhibit severe enough fatigue.

Laboratory tests can be useful to help diagnose and manage other conditions with similar symptoms and disorders that must be identified and treated before a diagnosis of CFS can be made. The CDC provides a set of basic tests that may be done, but these may vary depending on the healthcare provider:

Laboratory tests

Additional tests may be ordered to follow up abnormal findings on the general tests and as warranted by signs and symptoms. These additional tests are used to help identify or rule out diseases and disorders that may cause signs and symptoms similar to CFS, such as fatigue. A few examples include:

Non-laboratory tests
Occasionally, an MRI (magnetic resonance imaging) scan may be ordered to help rule out multiple sclerosis as a cause of chronic fatigue. Other tests and imaging scans may be used in a research setting but are not considered clinically useful at this time.

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