Fatigue

I. Background
A. General considerations
Fatigue is a very common complaint in the primary care office. It may be the primary reason a patient seeks care or a secondary complaint. We are all bothered by fatigue at some point in time. However, for millions of patients each year, it becomes bothersome enough to seek medical attention. True fatigue needs to be distinguished from weakness and from excessive somnolence secondary to sleep disturbances. Fatigue lasting less than a month is considered acute. If symptoms last more than a month, fatigue is considered prolonged.
B. Definitions
  • Chronic fatigue is diagnosed when symptoms last >6 months. The Center for Disease Control and Prevention has defined chronic fatigue syndrome (CFS) as profound fatigue of 6 months duration that presents with four of the following eight symptoms:
    • Impairment in short-term memory or concentration
    • Sore throat
    • Tender lymphadenopathy
    • Myalgias
    • Multijoint pain
    • Headaches of a new type, pattern, or severity
    • Unrefreshing sleep
    • Postexertional malaise lasting >24 hours (1)
  • Idiopathic chronic fatigue is diagnosed if a patient has been fatigued for ox>6 months, but does not meet the other criteria for CFS.
II. Pathophysiology
A. Etiology
Some of the common causes of CFS are listed in Table 2.5.1. Fatigue may be due to medical disorders, psychiatric disease, or lifestyle factors. In some cases, a cause is never determined. Fatigue that persists for several months or years is more likely to have a psychiatric etiology, whereas a shorter duration of fatigue is more likely to have a medical explanation (2). If a medical cause of fatigue is present, it is usually identifiable on the initial history, physical and laboratory testing (3).
B. Epidemiology
The true incidence of profound fatigue is unknown. It has been estimated that over 7 million office visits per year are for complaints of fatigue (3). The true gender predilection is also unknown, however, women present to the physician's office twice as often as men. Patients younger than 45 years of age are more likely to present for fatigue than patients older than 45 years of age (2).
III. Evaluation
A. History
  • A detailed history and review of systems should be performed. The onset, duration, and degree of fatigue should be explored, along with any possible precipitating events. Specific attention should be given to sleep patterns, daytime somnolence, or sleep apnea symptoms.
  • The patient's exercise habits, caffeine intake, and drug or alcohol use should be explored, and medications should be reviewed.
  • A psychiatric history to evaluate symptoms of depression or anxiety should be obtained. Lifestyle issues such as stress at home or in the work place, childcare responsibilities, shift work, or changing work schedules should be addressed.
B. Physical examination
A thorough physical examination should be performed. Vital signs should be carefully noted. Attention should be given to the presence of pallor, muscle weakness, goiter, lymphadenopathy, and body habitus. A psychiatric for signs of depression, anxiety, or other mental illness should be performed. In older adults, a mental status exam to evaluate cognitive function may be appropriate.
TABLE 2.5.1 Common Causes of Fatigue
Medical conditions Psychiatric disorders Lifestyle factors
Hypothyroidism
Anemia
Cardiomyopathy
COPD
Morbid obesity
Sleep disorders
Medication side effects
   β-Blockers
   Centrally acting α-Blockers
   Antihistamines
   Antidepressants
Subacute infections
   Viral infections (CMV, EBV, HIV)
   Bacterial endocarditis
Malignancy
Fibromyalgia		 Major depressive disorder
Bipolar disorder
Alcoholism/substance abuse
Anxiety
Somatoform disorders		 Sleep deprivation
Marital discord
Job stress
Caring for young children
Altering work schedule
COPD, chronic obstructive pulmonary disease; CMV, cytomegalovirus; EBV, Epstein-Barr virus; HIV, human immunodeficiency virus.
C. Testing
  • Initial laboratory testing should be limited to:
    • Complete blood count
    • Comprehensive metabolic profile
    • Thyroid-stimulating hormone
    • Erythrocyte sedimentation rate
    • Urine analysis
  • Other tests may be indicated by the history or physical examination:
    • Antinuclear antibody
    • Rheumatoid factor
    • Monospot
    • Chest x-ray
    • Colonoscopy
    • Sleep study
  • Screening tests appropriate for age and gender should be performed.
IV. Diagnosis
Fatigue is a very commonly encountered complaint. In most cases, a thorough history, physical and a limited number of ancillary tests reveal a more precise diagnosis. Fatigue is rarely the only presenting symptom in cases of malignancy or connective tissue disease. Studies have shown that among patients with fatigue, approximately 40% have an underlying medical diagnosis, approximately 40% have a psychiatric diagnosis, and 12% have both medical and psychiatric explanations for their fatigue. Approximately 8% of patients have no discernible diagnosis (2). If undiagnosed fatigue persists for >6 months and meets the other criteria for CFS, that diagnosis is applied. If the other criteria for CFS are not met, the term idiopathic chronic fatigue is used. Fatigue that cannot be attributed to a medical or psychiatric diagnosis is often thought to be due to lifestyle factors.
References
1. Centers for Disease Control and Prevention. Chronic fatigue syndrome, accessed at National Center for Infectious Diseases (www.cdc.gov/ncidod/diseases/cfs/index.htm) on 13 May 2005.
2. Morrison JD. Fatigue as a presenting complaint in FP. J Fam Pract 1980;10:795 - 801.
3. Epstein KR. The chronically fatigued patient. Med Clin North Am 1995;79:315 - 327.
4. Craig T, Kakumanu S. Chronic fatigue syndrome: evaluation and treatment. Am Fam Physician 2002;65:1083 - 1089.