Fatigue

Fatigue, or the tendency to tire easily, is a common complaint in primary care. 

Psychological factors almost certainly play a role in most cases: 

• Even when an organic cause can be found to explain an abnormal lack of energy, an individual's threshold for complaining to the point of seeking medical attention will be influenced by such factors as stress and satisfaction with daily living. 

• The evaluation of chronic fatigue must always be accompanied by an evaluation for depression, which may be present as a primary or concomitant disorder. 

• Screening questionnaires such as the Beck Depression Inventory are easily administered in the primary care setting for this purpose and are equally useful in ruling out significant depression as they can be to uncover true cases requiring further evaluation and possibly treatment.

Fatigue must be distinguished from weakness or excessive somnolence. The former is reproducible on physical examination, while the latter symptom is characterized by a difficulty or inability to remain awake during situations where sleepiness is not common and is obviously detrimental. 

• It is always abnormal for a person to fall asleep while talking, eating, driving, or operating machinery. 

• The tendency to fall asleep in the afternoon or while reading may be abnormal if an individual reports it as new or as seriously debilitating, but may also be a common complaint of normal persons. 

Normal people generally require between 6 and 8 hours uninterrupted sleep per 24 hours. Many people function apparently normally with less sleep, often for long periods of time (weeks), although a period of "catch-up" sleep (for example, during a weekend) can often be elicited from a careful history. The long term health risks from chronic low level sleep deprivation are unknown. If a patient with excessive daytime somnolence does not admit to any degree of sleep deprivation, a specialty evaluation to rule out sleep apnea syndromes and/or narcolepsy is indicated. Although the typical sleep apnea patient is overweight and snores, these need not always be present. 

• Due to the arduous nature of military duty and the dangers of operating equipment while sleepy, reports of excessive daytime somnolence must be taken very seriously. 

• Another screening questionnaire such as the Epworth Sleepiness Score may be useful to gauge the seriousness of a complaint of sleepiness or fatigue. 

• Patients with high scores should be relieved of dangerous duties including long haul driving and flight status, and prompt evaluation undertaken. 

Because the complaint of fatigue may be so subjective, ask specific questions concerning levels of possible activity as well as specific limiting factor:

• What was the previous highest level of functioning? 

• How recently was that level being achieved? 

• If a patient used to run 10 miles a day but now cannot climb ladders on a ship without dyspnea, something is obviously wrong. 

• But if the patient describes running track and field in high school, and now several years later reports only a vague sense of not being able to do heavy manual labor without fatigue, the importance of this limitation may be difficult to gauge. Indeed, even during subspecialty evaluation of chronic unexplained fatigue, specialized testing may be necessary to determine how much work can be performed with an observable degree of effort. 

• A patient's medications must always be scrutinized. Drugs used to treat hypertension are commonly implicated as causing fatigue. Other medications, herbals, and occasionally oral contraceptives(1) may be temporally related to the onset of fatigue. When in doubt, a trial of discontinuing or switching to other drugs is indicated.

Although many people complaining of fatigue will have no identifiable illness, others with a complaint of similar or even lesser severity may actually be quite ill. An example may be the highly motivated sailor who develops sarcoidosis. In this case the physical exam may be quite normal but the patient will complain of just not being able to do all of what he or she has been used to, or of becoming short of breath or extremely tired while doing so. Frequently such individuals will "push" themselves so that by the time they present for medical attention their disease may be in full bloom. 

Systemic illness may cause fatigue. Accordingly, a complete physical examination is always indicated. Special attention should be placed on looking for swollen lymph glands (infection, HIV, lymphoma), diffuse skin pigment or texture changes (endocrine disorders), or neurological findings (weakness or asymmetric function). Multiple sclerosis is just one disorder that may present as episodic weakness or fatigue in young adults. 

When physical exam and history do not provide a clear or likely explanation for a person's complaint of fatigue, screening lab tests should be ordered. These include:

• CBC

• ESR

• TSH

• Chemistry panel including electrolytes, glucose, and measures of kidney and liver function. 

The main diseases one is seeking to rule out are anemia, hypo- or hyperthyroidism, diabetes, and occult inflammation. Low potassium will be seen in familial periodic paralysis, which presents as episodic profound weakness and fatigue, usually after a large carboydrate meal. Addison's disease (adrenal hypofunction) or Cushing's syndrome (excessive cortisol) may be suspected by abnormal electrolyte concentrations. A chest x-ray ought to be performed if there is any suspicion of organic unidentified illness because of the low but definite possibility of occult malignancy (Hodgkin's Disease, lung cancer, and others).

When sleep deprivation is ruled out, the physical examination is normal, screening laboratory tests are normal, and there is no excessive daytime somnolence, one may be dealing with a case of chronic fatigue syndrome (CFS). This difficult disorder remains controversial, but is probably due to infection in a least a small minority of cases. Criteria for CFS promulgated by the Center For Disease Control are listed in the Table. Rigorous attention to ruling out organic disorders before recommending psychological or psychiatric evaluation is important. 

TABLE 1. DIAGNOSTIC CRITERIA FOR CHRONIC FATIGUE SYNDROME 

Unexplained, persistent, or relapsing chronic fatigue that is new or had a definite onset, is not due to ongoing exertion, is not substantially alleviated by rest, and substantially reduces occupational, educational, social, or personal activities 

-PLUS-

At least four of the following for >= 6 months (note: these symptoms must NOT have predated the onset of fatigue)

• Impaired short-term memory or concentration (self-reported) severe enough to substantially reduce occupational, educational, social, or personal activities 

• Sore throat 

• Tender cervical or axillary lymph nodes 

• Muscle pain 

• Multijoint pain without joint swelling or tenderness 

• Headaches of new type, pattern, or severity 

• Unrefreshing sleep 

• Postexertional malaise lasting > 24 hours

The Epworth Sleepiness Scale (ESS)

The Epworth Sleepiness Scale (ESS) has been proposed as a simple method to reliably quantify the key symptom of excessive sleepiness (M. Johns, "Daytime sleepiness, snoring, and obstructive sleep apnea. The Epworth Sleepiness Scale." Chest 1993;103:30). 

This is a self-administered, eight question test that measures sleep propensity and further correlates with a measure of sleep apnea called the Respiratory Disturbance Index. The patient rates from zero to three the likelihood of falling asleep in various situations, and a total score is obtained, ranging from zero to 24. 

In one report, all patients with severe obstructive sleep apnea (OSA) had totals above 10; the average score was 12 for all patients with any degree of OSA. 

Many specialty clinics incorporate this simple questionnaire in their initial office visit.(3) Of course patients must be honest about answering the questions, so the use of such a questionnaire can never substitute for a directed history and physical exam. 

REFERENCES: 

1. Smith JM and Huggins GR. Chapter 93, "Birth Control," in Barker, et.al. Principles of Ambulatory Medicine, Fifth Ed. Williams and Wilkins, 1999.
2.  Data from the Centers for Disease Control and Prevention, the National Institutes of Health, and the International Chronic Fatigue Study Group. 
3.  Kline, LR. Clinical presentation and diagnostic approach to sleep apnea. In: UpToDate, Rose, BD (Ed.), Vol 8.3, 2000. UpToDate, Wellesley, MA. 

ADDITIONAL READING

1. The Merck Manual of Diagnosis and Therapy - 17th Ed. (1999), CHAPTER 287. Syndromes of Uncertain Origin: Chronic Fatigue Syndrome.

2. Fosnocht, KM and Ende, J. Approach to the Patient With Fatigue. In: UpToDate, Rose, BD (Ed.), Vol 8.3, 2000. UpToDate, Wellesley, MA. 

3. Buchwald, D, Umali, P, Umali, J, et al. Chronic fatigue and the chronic fatigue syndrome: Prevalence in a pacific northwest health care system. Ann Intern Med 1995; 123:81 

4. Aaron, LA, Burke, MM, Buchwald, D. Overlapping conditions among patients with chronic fatigue syndrome, fibromyalgia, and temporomandibular disorder. Arch Intern Med 2000; 160:221.

5. Fukuda, K, Straus, SE, Hickie, I, et al. The chronic fatigue syndrome: A comprehensive approach to its definition and study. International Chronic Fatigue Syndrome Study Group. Ann Intern Med 1994; 121:953.

6. Ridsdale, L, Evans, A, Jerrett, W, et al. Patients who consult with tiredness: Frequency of consultation, perceived causes of tiredness and its association with psychological distress. Br J Gen Pract 1994; 44:413.

This section provided by CDR Dominick A. Rascona, MC, USNR, Naval Medical Center Portsmouth

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