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Diagnostic Tests to Exclude Other Causes

Tests for Routine Diagnosis of CFS

While the number and type of tests performed may vary from doctor to doctor, the following tests constitute a typical standard battery to exclude other causes of fatiguing illness:

  • alanine aminotransferase (ALT)
  • albumin, alkaline phosphatase (ALP)
  • blood urea nitrogen (BUN)
  • calcium
  • complete blood count with differential
  • creatinine
  • electrolytes
  • erythrocyte sedimentation rate (ESR)
  • globulin
  • glucose
  • phosphorus
  • thyroid stimulating hormone (TSH)
  • total protein
  • transferrin saturation
  • urinalysis

Further testing may be required to confirm a diagnosis for illness other than CFS. For example,

  • If a patient has low levels of serum albumin together with an above-normal result for the blood urea nitrogen test, kidney disease would be suspected. The doctor may choose to repeat the relevant tests and possibly add new ones aimed specifically at diagnosing kidney disease.
  • If autoimmune disease is suspected on the basis of initial testing and physical examination, the doctor may request additional tests, such as for antinuclear antibodies.

Assessing the Impact of Fatigue on Cognition

For some patients, it may be beneficial to conduct tests to assess how fatigue is affecting their cognitive skills such as concentration, memory, and organization. This additional testing can be useful in the differential diagnosis process or in identifying specific areas in which therapy may help. This may be particularly helpful to children and adolescents with CFS. Academic attendance and performance are important in these patients, and their specific educational needs should be addressed.

Tests for Differential Diagnosis and Management

CFS remains a diagnosis based on medical history, illness symptoms, physical examination, and exclusion of certain illnesses using a standard group of laboratory tests (1994 case definition). Additional tests such as imaging and physiological assessments can also be used to diagnose underlying illnesses:

  • specific cultures or serological tests if an ongoing infection is considered
  • MRI or other neuroimaging procedures to test for diseases such as multiple sclerosis
  • physiological testing such as sleep studies, exercise testing (including VO2 max), or tilt table testing to address specific questions, often in consultation with a specialist

Be aware that a patient can have CFS as well as a co-existing illness that cause fatigue or other CFS symptoms – for example, depression or low blood pressure. If treatment of those other illnesses does not resolve the symptoms, then the person can still have CFS.

Additional Diagnostic Resources for Healthcare Professionals

Several resources have been created to assist health care professionals in diagnosing and managing CFS. These resources can be accessed below:

CFS Toolkit

The toolkit is designed to help break the cycle of frustration. It provides a quick and easy-to-use resource for clinical care.

Free Continuing Education Course

"Chronic Fatigue Syndrome: Diagnosis and Management" is a two-hour Web-based self-study course intended for primary care professionals, rehabilitation specialists and behavioral health professionals.


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