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Chapter 7. Fatigue

Richard J. Simons, MD; Nicole A. Swallow, MD

A 45-year-old woman presents to your clinic after suffering from “months” of feeling bad. She feels tired all the time and is finding it difficult to keep up daily activities. Her tiredness is interfering with her ability to play an active role in the lives of her husband and 2 children. She has no significant past medical history and has not seen a physician in several years.

  • What additional information about her “tiredness” do you need?
  • How would you classify her fatigue?
  • What alarm symptoms would you look for in this patient?
  • Would laboratory testing help you to make a diagnosis?

Fatigue is one of the most common symptoms encountered in primary care settings. Twenty-four percent to 32% of adult patients report significant fatigue during visits to their primary care physicians.1,2 Fatigue is a sensation that everyone experiences from time to time; however, it is the persistence of fatigue that is considered abnormal. Common descriptors from patients with fatigue include a lack of energy to complete tasks, exhaustion, and tiredness. Fatigue often signifies underlying medical or psychiatric disease.

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Chronic fatigueGenerally implies fatigue persisting for 6 months.
Chronic fatigue syndrome (CFS)

Unexplained, persistent, or relapsing fatigue that is of new or definite onset; is not the result of ongoing exertion; is not alleviated by rest; and results in substantial reduction in previous levels of occupational, educational, social, or personal activities and 4 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:

  1. Self-reported impairment in short-term memory or concentration

  2. Sore throat

  3. Tender cervical or axillary nodes

  4. Muscle pain

  5. Multiple joint pain without redness or swelling

  6. Headaches of a new pattern or severity

  7. Unrefreshing sleep

  8. Postexertional malaise lasting 24 hours4

Idiopathic fatigue (IF)Fatigue that has not been attributed to a psychiatric or medical illness.
Persistent fatigueFatigue that generally persists for more than 1 month.

The chronic fatigue syndrome (CFS) represents a very small subset of patients with chronic fatigue. CFS remains a controversial subject but probably has existed for centuries under various labels, including effort syndrome (soldier's heart described in 1870), neurasthenia (1890), and more recently, the Gulf War syndrome (1991). Recently, the Centers for Disease Control and Prevention (CDC) developed a tool to assist in the more definitive diagnosis of CFS, expanding upon previous work in this field.3 Unfortunately, because fatigue may accompany almost any medical or psychological illness, evaluating and treating a patient with fatigue can be particularly challenging and sometimes frustrating for the clinician. A careful history with special attention to psychosocial issues, the physical examination, and a few selected laboratory tests should reveal the cause in most patients.

Approximately 70% of patients with chronic fatigue are found to have a medical or psychological explanation.2,5 Psychiatric disorders (depression ...

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