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Diagnostic Challenges

Diagnosing chronic fatigue syndrome (CFS) can be challenging for health care professionals. A number of factors add to the complexity of making a CFS diagnosis: 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 remitting and relapsing course , 5) symptoms vary from person to person infrequency and severity, and 6) no two CFS patients have exactly the same pattern of symptoms.

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

Overcoming the Challenges

In spite of these challenges, CFS can be diagnosed in a primary care setting. The 1994 International Case Definition for CFS forms the basis of a reliable diagnostic algorithm for CFS, particularly in adults.

While there is evidence that children can get CFS, current research suggests that the illness isn't prevalent in younger children, particularly those under the age of 11. Diagnosing pediatric CFS can be more difficult than adult CFS because children may have difficulty recognizing and verbalizing their symptoms, and because they have a remarkable ability to become accustomed to symptoms and adapt to them. Clinicians assessing adolescents for CFS should exercise judgment based on the course of the illness and the patient's medical history.

Diagnostic Resources

Several resources have been created to assist health care professionals in diagnosing and managing CFS. These resources can be accessed below:

How Physicians Diagnose CFS

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 physician should further investigate the possibility that the patient may have CFS. The first step in this investigation is obtaining a detailed medical history and performing a complete physical examination of the patient. Initial testing should include a mental status examination, which ordinarily will involve a short discussion in the office or a brief oral test. A standard series of laboratory tests of the patient's blood and urine should be performed to help the physician identify other possible causes of illness. If test results suggest an alternative explanation for the patient's symptoms, additional tests may be performed to confirm that possibility. If no cause for the symptoms is identified, the physician may render a diagnosis of CFS if the other conditions of the case definition are met (see What Is CFS?). A diagnosis of insufficient fatigue could be made if a patient has been fatigued for 6 months or more, but does not meet the symptom criteria for CFS.

An Empirical Definition

Recently the definitional criteria have reached using information derived from 3 questionnaires: MOS SF-36, Multidimensional Fatigue Inventory, and the CDC Symptom Inventory (Reeves et al, 2005). This approach can be useful in identifying patient and in monitoring their illness course or response to treatment.

Appropriate Tests for Routine Diagnosis of CFS

While the number and type of tests performed may vary from physician to physician, the following tests constitute a typical standard battery to exclude other causes of fatiguing illness: alanine aminotransferase (ALT), albumin, alkaline phosphatase (ALP), blood urea nitrogen (BUN), calcium, complete blood count, creatinine, electrolytes, erythrocyte sedimentation rate (ESR), globulin, glucose, phosphorus, thyroid stimulating hormone (TSH), total protein, transferrin saturation, and urinalysis. Further testing may be required to confirm a diagnosis for illness other than CFS. For example, if a patient has low levels of serum albumin together with an above-normal result for the blood urea nitrogen test, kidney disease would be suspected. The physician may choose to repeat the relevant tests and possibly add new ones aimed specifically at diagnosing kidney disease. If autoimmune disease is suspected on the basis of initial testing and physical examination, the physician may request additional tests, such as for antinuclear antibodies.

Psychological/Neuropsychological Testing

In some individuals it may be beneficial to assess the impact of fatiguing illness on certain cognitive or reasoning skills, e.g., concentration, memory, and organization. This may be particularly relevant in children and adolescents, where academic attendance, performance, and specific educational needs should be addressed. Personality assessment may assist in determining coping abilities and whether there is a co-existing affective disorder requiring treatment.

Theoretical and Experimental Tests

A number of tests, some of which are offered commercially, have no demonstrated value for the diagnosis of CFS. These tests should not be performed unless required for diagnosis of a suspected exclusionary condition (e.g., MRI to rule out suspected multiple sclerosis) or unless they are part of a scientific study. In the latter case, written informed consent of the patient is required. No diagnostic tests for infectious agents, such as Epstein-Barr virus, enteroviruses, retroviruses, human herpesvirus 6, Candida albicans, and Mycoplasma incognita, are diagnostic for CFS and as such should not be used (except to identify an illness that would exclude a CFS diagnosis, such as mononucleosis). In addition, no immunologic tests, including cell profiling tests such as measurements of natural killer cell (NK) number or function, cytokine tests (e.g., interleukin-1, interleukin-6, or interferon), or cell marker tests (e.g., CD25 or CD16), have ever been shown to have value for diagnosing CFS. Other tests that must be regarded as experimental for making the diagnosis of CFS include the tilt table test for NMH, and imaging techniques such as MRI, PET-scan, or SPECT-scan. Reports of a pathway marker for CFS as well as a urine marker for CFS are undergoing further study; however, neither is considered useful for diagnosis at this time.


Diagnostic Resources

Several resources have been created to assist health care professionals in diagnosing and managing CFS. These resources can be accessed below:

CFS Toolkit: Fact Sheets
The toolkit is designed to help break the cycle of frustration. It provides a quick and easy-to-use resource for clinical care… Read more

Image of Resource GuideProvider Resource Guide
PDF file PDF (2 Pages / 122 KB)
This brochure will give health care professionals a brief overview of how to diagnose and recommend treatment for their patients with CFS.

Free Continuing Education Course
“Chronic Fatigue Syndrome: Diagnosis and Management” is a two-hour Web-based self-study course intended for primary care professionals, rehabilitation specialists and behavioral health professionals... Read more

Page last modified on May 9, 2006


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