Information for Physicians on Diagosing Chronic Fatigue Syndrome
The criteria for diagnosing Chronic Fatigue Syndrome were officially defined by the CDC in 1988 and revised in 2001 (CDC 2001). The Oxford criteria differ slightly. The British criteria insist upon the presence of mental fatigue, although the American criteria include a requirement for several physical symptoms, reflecting the belief that Chronic Fatigue Syndrome has an underlying immune or infectious pathology (Fauci et al. 1998; Reid et al. 2000).
Centers for Disease Control's Criteria for Chronic Fatigue Syndrome
Clinically evaluated, unexplained, persistent, or relapsing fatigue that is:
- Of new or definite onset
- Not a result of ongoing exertion
- Not alleviated by rest
- Results in a substantial reduction in previous levels of occupational, social, or personal activity
Four or more of the following symptoms that persist or recur during 6 or more consecutive months of illness and that do not predate the fatigue:
- Self-reported impairment of short-term memory or concentration
- Sore throat
- Tender lymph nodes
- Muscle pain
- Multijoint pain without swelling or redness
- Headaches of a new type, pattern, or severity
- Unrefreshing and/or interrupted sleep
- Postexertion malaise (a feeling of general discomfort or uneasiness) lasting more than 24 hours
Exclusion criteria:
- Active, unresolved or suspected disease that is likely to cause fatigue
- Psychotic, melancholic, or bipolar depression (but not uncomplicated major depression)
- Psychotic disorders
- Dementia
- Anorexia or bulimia nervosa
- Alcohol or other substance misuse
- Severe obesity
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Oxford (British) Criteria for Chronic Fatigue Syndrome
Severe disabling fatigue of at least a 6-month duration that:
- Affects both physical and mental functioning
- Is present for more than 50% of the time
Other symptoms, particularly myalgia and sleep and mood disturbances, may be present.
Exclusion criteria:
- Active, unresolved, or suspected disease that is likely to cause fatigue
- Psychotic, melancholic, or bipolar depression (but not uncomplicated major depression)
- Psychotic disorders
- Dementia
- Anorexia or bulimia nervosa
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Additional Symptoms:Although the symptoms heretofore listed are the official diagnostic criteria, many patients with Chronic Fatigue Syndrome present a variety of other symptoms, including:
- Pain (almost universal in chronic fatigue)
- Allergies
- Chemical sensitivities
- Secondary infections, including Candida and viral infections
- Cognitive impairment, including short-term memory loss, difficulty concentrating and doing word searches and math problems
- Digestive disturbances, such as chronic constipation or diarrhea
- Night sweats or spontaneous daytime sweats, unaccompanied by fever
- Headaches, migraines
- Weakness (paresis), muscle fatigue, and pain (fibromyalgia)
- Premenstrual syndrome (PMS)
- Sleep disorders, including excessive sleep (hypersomnia), light sleep, or an inability to sleep for more than an hour (hyposomnia), disturbing nightmares
- A period of 1-3 hours after awakening during which patients are too exhausted to get out of bed (dysania)
- Cystitis (inflammation of the urinary bladder), particularly interstitial cystitis in which urine cultures are negative
- Vision and eye problems, including sensitivity to light (photophobia), dry eyes, tunnel vision, night blindness, and difficulty focusing
An initial office examination may also find the following signs:
- Low blood pressure, particularly on standing (orthostatic hypotension)
- Low oral temperatures (less than 97°F)
- Slightly elevated oral temperatures (but less than 100°F) which are part of persistent flulike symptoms
- Increased heart rate (tachycardia)
- A positive Romberg test (unsteadiness when standing with eyes closed)
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Novel and Conventional Laboratory Tests
Doctors usually perform the following laboratory tests, when attempting to diagnose a patient with Chronic Fatigue Syndrome:
- Complete blood count (CBC) with differential
- Chem 20 panel
- Erythrocyte sedimentation rate (ESR), a marker of inflammation
- Urinalysis
Optional tests include:
- Antinuclear antibodies (ANA) and rheumatoid factor (RF). (These are tests for rheumatoid arthritis and SLE, systemic lupus erythematous.)
- Thyroid tests (T3, T4, TSH)
- Adrenal tests (a.m. and p.m. cortisol levels)
- Lyme titers and HIV serology
Specific tests that support (but do not necessarily confirm) a diagnosis of chronic fatigue include (Verillo et al. 1997):
- Tests for viral infections, such as cytomegalovirus, Epstein-Barr virus, human herpes virus 6, and coxsackievirus
- Immune system tests, including low natural killer (NK) cell counts, elevated interferon alpha, tumor necrosis-alpha, interleukins 1 and 2, T-cell activation, altered T4/T8 cell ratios, low T-cell suppressor cell (T8) count, fluctuating B- and T-cell counts, antinuclear antibodies, immunoglobin deficiency, antithyroid antibodies
- Exercise testing may show decreased cortisol levels after exercise, decreased cerebral blood flow after exercise, inefficient glucose utilization, and erratic breathing patterns
Research into the cause(s) of Chronic Fatigue Syndrome touches upon a vast array of systems and etiologies. Several laboratory tests, in addition to those mentioned above, may be helpful in guiding appropriate treatment. These would include:
- Functional assessments of the adrenal gland, including measurements of cortisol, DHEA (dehydroepiandrosterone), and DHEA-S
- Assessments of oxidative stress
- Homocysteine levels
- C-reactive protein, a sensitive marker of inflammation
- Toxin analysis, including heavy metals, pesticides, and organic chemicals
Source: American Association for Chronic Fatigue Syndrome, c/o Harborview Medical Center, 325 Ninth Avenue, Box 359780, Seattle, WA 98104
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