by EBSCO Medical Review Board

CFS can be hard to diagnose. It may take some time. There are many conditions that cause similar symptoms.

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

If tests are normal, the doctor may suspect CFS.

Diagnosis may be based on 3 of the following symptoms:

  • 6 or more months of severe tiredness—with reduced or impaired functioning that:
  • Affects daily activities, such as work and relationships
  • Does not get better with good sleep
  • Is not due to too much activity
  • Severe tiredness or muscle fatigue after activity—at least 50% of the time
  • Sleep problems at least 50% of the time—moderate to severe

One or both of these symptoms:

  • Problems with memory, focus, or thinking at least 50% of the time—moderate to severe
  • Lightheadedness or eyesight problems when standing or sitting up

Tests will be based on past health, a physical exam, and symptoms. Not everyone will have all tests. Tests may include:

Blood and Urine Tests

Blood tests may be done to check:

  • How the liver and kidneys are working
  • 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
  • Creatine kinase

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

Psychological and Neurological Tests

The doctor may want to test mental skills. These may include tests for focus, memory, and organization. A personality test may look at coping skills. They also look for any mental health problems such as:

Additional Tests

Other tests may include:

  • A sleep study—to rule out sleep disorders
  • Imaging tests—to look for brain and nerve problems


Chronic fatigue syndrome. EBSCO DynaMed website. Available at: Accessed April 12, 2022.

Chronic fatigue syndrome. Merck Manual Professional Version website. Available at: Accessed April 12, 2022.

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. Washington (DC): National Academies Press (US); 2015 Feb 10. Available at:

Diagnosis of ME/CFS. Centers for Disease Control and Prevention website. Available at: Accessed April 12, 2022.

Revision Information