who can diagnose chronic fatigue syndrome

There’s no single test to confirm a diagnosis of chronic fatigue syndrome. Because the symptoms of chronic fatigue syndrome can mimic so many other health problems, you may need patience while waiting for a diagnosis.

Your doctor must rule out a number of other illnesses before diagnosing chronic fatigue syndrome.

These may include:

Sleep disorders. Chronic fatigue can be caused by sleep disorders. A sleep study can determine if your rest is being disturbed by disorders such as obstructive sleep apnea, restless legs syndrome or insomnia.
Medical problems. Fatigue is a common symptom in several medical conditions, such as anemia, diabetes and underactive thyroid (hypothyroidism). Lab tests can check your blood for evidence of some of the top suspects.
Mental health issues. Fatigue is also a symptom of a variety of mental health problems, such as depression, anxiety, bipolar disorder and schizophrenia. A counselor can help determine if one of these problems is causing your fatigue.

To meet the diagnostic criteria of chronic fatigue syndrome, or myalgic encephalomyelitis, you must have unexplained, persistent fatigue for six months or more, along with at least four of the following signs and symptoms:

Loss of memory or concentration
Sore throat
Enlarged lymph nodes in your neck or armpits
Unexplained muscle pain
Pain that moves from one joint to another without swelling or redness
Headache of a new type, pattern or severity
Unrefreshing sleep
Extreme exhaustion lasting more than 24 hours after physical or mental exercise

In contrast, for a diagnosis of systemic exertion intolerance disease (SEID), you must have the following three symptoms:

Unexplained, persistent fatigue
Extreme exhaustion lasting more than 24 hours after physical or mental exercise
Unrefreshing sleep

And at least one of these two symptoms:

Cognitive impairment
Dizziness and lightheadedness

Chronic fatigue accompanies many medical conditions and may not be an isolated symptom. In such cases, the better term may be "chronic multifactorial fatigue.