Fatigue

Differential Overview

❑ Infectious mononucleosis

❑ Depression

❑ Diabetes

❑ Hypothyroidism

❑ Drugs

❑ Chronic sleep deprivation

❑ Congestive heart failure

❑ Occult infection

❑ Iron deficiency anemia

❑ Obstructive sleep apnea

❑ Renal failure

❑ Chronic fatigue syndrome

❑ Cushing syndrome

❑ Occult cancer

❑ Addison disease

❑ Myasthenia gravis

Diagnostic Approach

Organic fatigue is characterized by physical weakness or exhaustion, which is exacerbated by activity and partially relieved by sleep, short duration (,2 months), unintentional weight loss of greater than 10%, and an ill appearance. Most organic causes have associated signs and symptoms, specific and few in number.

Psychological fatigue is characterized by a primary inertia to initiation of physical activity, which when undertaken, can be performed. The patient is tired all the time, but fatigue is not exacerbated by exertion or relieved by rest. A protracted course, multiple and nonspecific associated symptoms, relation to stressful life events, and an anxious or depressed appearance are other clues. The sick role response to prior minor illness can indicate likely response to the current illness.

A medical or psychiatric diagnosis can be found in over two-thirds of patients with more than one month of fatigue. Psychiatric diagnoses, especially depression, panic disorder, or somatization disorder are the most common.

A diagnostic approach that involves careful history-taking and physical examination, assiduous avoidance of early closure, and a clear orientation to the reality of the patient’s perceptions whatever the cause (i.e., never implying “It’s all in your head”), is most rewarding. The differential is wide, and identification of the unusual organic causes among the many psychophysiological ones takes great skill.

Clinical Findings

Infectious mononucleosis  Acute onset of prominent fatigue in a young adult is accompanied by sore throat, fever, posterior cervical lymphadenopathy, and splenomegaly. The symptoms do not begin to resolve as quickly as with other causes of pharyngitis.

Depression  Depressed mood is usually recognized by the patient, but the physical manifestations such as fatigue, sleep disturbance, anorexia, or anhedonia may obscure the diagnosis.

Diabetes  Usually presents with concurrent weight loss and polyuria/nocturia.

Hypothyroidism  Fatigue is prominent, but other symptoms and findings, including weight gain, dry skin, hoarseness, constipation, cold intolerance, periorbital edema, delayed relaxation phase to the ankle jerks, goiter, and thinning of the lateral third of the eyebrows, suggest the diagnosis.

Drugs  Beta blockers, reserpine, diuretics (primarily via hypokalemia), antihistamines, antidepressants, tranquilizers, steroids, narcotics, and alcohol can cause fatigue as a side effect.

Chronic sleep deprivation  This is a common cause of fatigue in workers who alter shifts, parents of young children, international travelers, and in patients with depression or fibromyalgia. Excessive daytime sleepiness in combination with heavy snoring should suggest obstructive sleep apnea.

Congestive heart failure  Early disease may be suggested by paroxysmal nocturnal dyspnea and exertional fatigue. Fatigue indicates reduced cardiac output.

Occult infection  The hallmark is fever. Endocarditis, tuberculosis, HIV, HBV, and occult abscess should be considered.

Iron deficiency anemia  Fatigue may be associated with severe, but usually not mild, anemia. Menstrual blood loss and gastrointestinal blood loss are common causes.

Obstructive sleep apnea  Excessive daytime somnolence is the prominent symptom. Obesity and the bedmate reporting heavy snoring followed by apneic periods are additional clues.

Renal failure  Edema and foamy urine are present if there is proteinuria. The skin is sallow in color.

Chronic fatigue syndrome  CFS is defined as lasting longer than 6 months, during which the affected person has less than 50% physical capacity. Associated symptoms and findings include recurrent sore throat, lymphadenopathy, myalgia, headache, and sleep disorder. If tender trigger points are present, the fibromyalgia end of the diagnostic spectrum should be considered.

Cushing syndrome  Indicators include hypertension, moon facies, purple striae, truncal obesity, and a “buffalo hump.” Suspect this syndrome in patients taking steroids.

Occult cancer  Leukemia, lymphoma, and pancreatic cancer commonly present with fatigue. Adenopathy, splenomegaly, and night sweats are helpful clues.

Addison disease  Look for hyperpigmentation, especially of the palmar creases and buccal mucosa. Suspect adrenal insufficiency in patients recently withdrawn from steroids. Concomitant symptoms include weakness, weight loss, anorexia, and hypotension.

Myasthenia gravis  Muscle weakness characteristically increases with repeated use. Early disease involves cranial muscles with ptosis, diplopia, and chewing fatigue. Proximal limb weakness soon develops. The “peek sign” has a likelihood ratio of 30: Orbicularis oculi weakness is observed on gentle eye closure. After initial complete apposition of the lid margins, they separate within seconds and the white of the sclera peeks through.

Book Source Details

• Book Title: Field Guide to Bedside Diagnosis
• Author(s): David S. Smith
• Year of Publication: 2007
• Copyright Details: Field Guide to Bedside Diagnosis, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright Details: Field Guide to Bedside Diagnosis, Copyright © 2008 Williams & Wilkins.

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More About This Book: Title: Field Guide to Bedside Diagnosis Authors: David S. Smith Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-78178-165-5

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