Carl R. Darnall Army Medical Center - Health Library

Diagnosis of Chronic Fatigue Syndrome (CFS)

CFS can be hard to diagnose. It may take some time. This can feel frustrating but you can work to relieve symptoms while you are waiting.

The doctor will ask about your symptoms. You will also be asked about your family and health past. There are no standard tests for CFS. However, tests may be done to rule out other issues. People with CFS often have normal physical exams and test results.

If you have symptoms but tests are normal, the doctor may begin to suspect CFS. The Institute of Medicine has a list of criteria to diagnose CFS. All 3 of the following symptoms must be present:

  • 6 months or more of decreased ability to activity level that you had before the onset of illness. Fatigue does not get better with good sleep.
  • Severe fatigue/muscle fatigue at least 50% of the time with moderate to severe intensity.
  • Sleep problems at least 50% of the time with moderate to severe intensity.

In addition, 1 or both of the following must also be present:

  • Trouble with short-term memory or concentration, forgetfulness, or confusion at least 50% of the time. With moderate to severe intensity.
  • Lightheadedness or vision problems when standing or sitting up. Symptoms worsen when upright, but improve when lying down.

Testing is done based on your medical history, physical exam, and symptoms. Not everyone will have all tests. Tests may include:

Blood and Urine Tests

Blood tests may be done to check:

  • Liver function
  • Kidney function
  • Calcium levels
  • Vitamin D levels
  • Red and white blood cell, and platelet counts—complete blood count (CBC)
  • Electrolyte levels such as salt and potassium
  • Inflammation—erythrocyte sedimentation rate (ESR)
  • Glucose levels
  • Phosphorus levels
  • Thyroid function—thyroid stimulating hormone (TSH)
  • Total protein levels
  • Iron levels

Urine tests can help to find infections or changes in the kidneys.

Other tests may include imaging tests or a .

Psychological and Neurological Tests

The doctor may want to test mental skills. You may have tests for concentration, memory, and organization. A personality assessment can help to determine your coping abilities. It is also done to identify any mental health issues that may also be present. These may include: .

Additional Tests

May include:


Chronic fatigue syndrome. EBSCO DynaMed Plus website. Available at: Updated August 30, 2018. Accessed May 4, 2018.

Chronic fatigue syndrome. Merck Manual Professional Version website. Available at: Updated October 2016. Accessed May 4, 2018.

Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, Board on the Health of Select Populations, Institute of Medicine. Beyond myalgic encephalomyelitis/chronic fatigue syndrome: redefining an illness. Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Washington (DC): National Academies Press (US); 2015 Feb 10. Available at:

Diagnosis. Centers for Disease Control and Prevention website. Available at: Updated July 4, 2017. Accessed May 4, 2018.

Last reviewed May 2017 by EBSCO Medical Review Board James P. Cornell, MD  Last Updated: 5/4/2018