Diagnostic Challenges
Diagnosing chronic fatigue syndrome (CFS) can be complicated by a number of factors: 1) there's no diagnostic laboratory test or biomarker for CFS, 2) fatigue and other symptoms of CFS are common to many illnesses, 3) CFS is an invisible illness and many patients don't look sick, 4) the illness has a pattern of remission and relapse, 5) symptoms vary from person to person in type, number and severity, and 6) no two CFS patients have exactly the same symptom set.
These factors have contributed to an alarmingly low diagnosis rate. Of the four million Americans who have CFS, less than 20% have been diagnosed.
Clinical Evaluation
Because there is no blood test, brain scan or other lab test to diagnose CFS, it's a diagnosis of exclusion. Your health care professional will first take a detailed patient history, including a review of medications that could be causing your fatigue. A thorough physical and mental status examination will also be performed. Next, a battery of laboratory screening tests will be ordered to help identify or rule out other possible causes of your symptoms. Your professional may also order additional tests to follow up on results of the initial screening tests.
The following summary is the procedure recommended by a panel of chronic fatigue syndrome (CFS) experts for clinically evaluating and classifying chronic fatigue. It is designed to help you better understand the process that your physician used (or will use) to reach (or exclude) a diagnosis of chronic fatigue syndrome.
Step One:
Your doctor will obtain a detailed medical history from you by asking a series of questions. This will be followed by a complete examination.
Step Two:
Your doctor will conduct a mental status examination. Usually, this will entail just a short discussion in the office or a brief oral test.
Step Three:
A standard series of laboratory tests will be performed on blood and urine specimens to help identify alternative causes of fatigue.
Step Four:
If your initial test results suggest an alternative explanation for your fatigue, additional laboratory testing may be required to confirm a diagnosis. If no cause for chronic fatigue is identified at this point, your doctor will proceed to the next step.
Step Five:
A patient will be classified as having CFS if he or she meets the following two criteria:
- 1. Unexplained fatigue that is not due to ongoing exertion, is not relieved by rest, and results in a substantial reducation in previous levels of activity, and...
- 2. If four or more of the following symptoms are concurrently present for six months or more:
- impaired memory or concentration
- sore throat
- tender cervical or axillary lymph nodes
-
muscle pain
- multi-joint pain
- new headaches
-
unrefreshing sleep
- post-exertional malaise
If a patient's fatigue is not severe enough, or if the symptom criteria for CFS are not met, he or she will be classified as having idiopathic (defined) chronic fatigue.
Placing various fatigued patients into specific categories provides scientists with a convenient means for comparing CFS patients with other forms of unexplained fatigue, thus enabling them to search more effectively for any clinical markers that may be unique to CFS.
Exclusionary Conditions
Chronic fatigue syndrome can resemble many other illnesses, including mononucleosis, Lyme disease, lupus, multiple sclerosis, fibromyalgia, primary sleep disorders, severe obesity and major depressive disorders. 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 needs to be treated. 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.
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