What's the Difference Between Chronic Fatigue & Chronic Fatigue Syndrome?
The terms "chronic fatigue" and "chronic fatigue syndrome" (CFS or ME/CFS) often are used interchangeably, but they're actually 2 very different conditions that are diagnosed and treated differently.
Understanding Fatigue
Fatigue is one of the most common complaints doctors hear. Much of the time it's caused by stress, lack of sleep, overexertion or minor illness such as a cold. Typically, fatigue goes away when you get rest or recover from being sick.
In both chronic fatigue and ME/CFS, fatigue is extreme and constant. It makes it difficult or impossible for you to function at even the most basic level. Think of the way you felt the last time you were seriously ill, severely sleep deprived, or coming out from under anesthesia -- that's the kind of fatigue we're talking about.
What is Chronic Fatigue (Without the "Syndrome")?
If you have simply chronic fatigue, it means that you have exhaustion or lack of energy for 6 months or longer. Chronic fatigue is generally a symptom of something else, such as:
- Infection
- Immune or autoimmune disorders (such as lupus or rheumatoid arthritis)
- Muscle or nerve diseases (such as multiple sclerosis)
- Endocrine diseases (such as hypothyroidism)
- Depression
- Organ disease
- Fibromyalgia
- Sleep disorders or ongoing lack of sleep
- High stress levels
- Nutritional deficiency
Some causes of chronic fatigue (such as lack of sleep, nutritional deficiency or short-term infection) have an obvious solution and are somewhat easy to correct. When caused by a chronic illness, chronic fatigue can be treated but not cured.
In some cases, doctors can't figure out the cause of chronic fatigue, but the person doesn't meet the diagnostic criteria for ME/CFS. Those cases are diagnosed as idopathic chronic fatigue. (Idiopathic means without known cause.)
Chronic Fatigue Syndrome
To get a diagnosis of chronic fatigue syndrome, you need more than extreme, persistent fatigue that lasts longer than 6 months. You've also got to have at least four of the following, also for longer than 6 months but starting after the fatigue:
- Impaired memory or concentration
- Post-exertional malaise (extreme, prolonged exhaustion and sickness following physical or mental activity)
- Unrefreshing sleep
- Muscle pain
- Joint pain without swelling or redness
- Headaches of a new type or severity
- Sore throat that's frequent or recurring
- Tender cervical or axillary lymph nodes
In addition to these diagnostic criteria, ME/CFS has about 50 recognized symptoms, including dizziness and balance problems, allergies and chemical sensitivities, anxiety, stiffness, numbness, and irregular heart beat. While not required for a diagnosis, these other symptoms can help your doctor identify what's going on in your body.
So far, doctors don't have a diagnostic test that can accurately detect ME/CFS. The condition is not curable, and so far no medications are FDA approved as treatments for it. Researchers are, however, getting closer to understanding the causes of ME/CFS and learning more about treatments.
Sources:
2008 A.D.A.M. Illustrated Encyclopedia, About.com, a part of the New York Times Company. All rights reserved. "Chronic fatigue syndrome"
June 2003 National Institutes of Health. "Chronic Fatigue Research: Challenges and Opportunities."
2007 University of Maryland Medical Center (UMMC). All rights reserved. "Chronic Fatigue Syndrome"
