Diagnosis

Diagnostic Challenges

For doctors, diagnosing chronic fatigue syndrome (CFS) can be complicated by a number of factors:

1. There's no lab test or biomarker for CFS.
2. Fatigue and other symptoms of CFS are common to many illnesses.
3. For some CFS patients, it may not be obvious to doctors that they are ill.
4. The illness has a pattern of remission and relapse.
5. Symptoms vary from person to person in type, number, and severity.

These factors have contributed to a low diagnosis rate. Of the one to four million Americans who have CFS, less than 20% have been diagnosed.

Exams and Screening Tests for CFS

Because there is no blood test, brain scan, or other lab test to diagnose CFS, the doctor should first rule out other possible causes.

If a patient has had 6 or more consecutive months of severe fatigue that is reported to be unrelieved by sufficient bed rest and that is accompanied by nonspecific symptoms, including flu-like symptoms, generalized pain, and memory problems, the doctor should consider the possibility that the patient may have CFS. Further exams and tests are needed before a diagnosis can be made:

• A detailed medical history will be needed and should include a review of medications that could be causing the fatigue and symptoms
• A thorough physical and mental status examination will also be needed
• A battery of laboratory screening tests will be needed to help identify or rule out other possible causes of the symptoms that could be treated
• The doctor may also order additional tests to follow up on results of the initial screening tests

A CFS diagnosis requires that the patient has been fatigued for 6 months or more and has 4 of the 8 symptoms for CFS for 6 months or more. If, however, the patient has been fatigued for 6 months or more but does not have four of the eight symptoms, the diagnosis may be idiopathic fatigue.

For Doctors and Other Healthcare Professionals: Criteria for Diagnosing CFS

Consider a diagnosis of CFS if these three criteria are met:

1.  The individual has severe chronic fatigue for 6 or more consecutive months that is not due to ongoing exertion or other medical conditions associated with fatigue (these other conditions need to be ruled out by a doctor after diagnostic tests have been conducted)
2.  The fatigue significantly interferes with daily activities and work
3.  The individual concurrently has 4 or more of the following 8 symptoms:

• post-exertion malaise lasting more than 24 hours
• unrefreshing sleep
• significant impairment of short-term memory or concentration
• muscle pain
• multi-joint pain without swelling or redness
• headaches of a new type, pattern, or severity
• tender cervical or axillary lymph nodes
• a sore throat that is frequent or recurring

For Patients Who Think They Might Have CFS

It can be difficult to talk to your doctor or other health care professional about the possibility that you may have CFS. A variety of health care professionals, including doctors, nurse practitioners, and physician assistants, can diagnose CFS and help develop an individualized treatment plan for you.

CFS can resemble many other illnesses, including mononucleosis, Lyme disease, lupus, multiple sclerosis, fibromyalgia, primary sleep disorders, and major depressive disorder. Medications can also cause side effects that mimic the symptoms of CFS.

Because CFS can resemble many other disorders, it's important not to self-diagnose CFS. It's not uncommon for people to mistakenly assume they have chronic fatigue syndrome when they have another illness that will respond to treatment. If you have CFS symptoms, consult a health care professional to determine if any other conditions are responsible for your symptoms. A CFS diagnosis can be made only after other conditions have been excluded.

It's also important not to delay seeking a diagnosis and medical care. CDC research suggests that early diagnosis and treatment of CFS can increase the likelihood of improvement.