Fatigue occurs most often as part of a symptom complex, but even when it is the sole or main presenting symptom, fatigue is one of the most common symptoms. Fatigue is difficulty initiating and sustaining activity due to a lack of energy and accompanied by a desire to rest. Fatigue is normal after physical exertion, prolonged stress, and sleep deprivation.

Fatigue is a desire to rest that reflects exhaustion. It differs from weakness, inability to move, and reluctance to move because of pain with movement. Fatigue may reflect activity of a systemic inflammatory disorder.

The most common disorders manifesting predominantly as recent fatigue (lasting lest than 1 month) are

• Drug adverse effects
• Anemia
• Stress and/or depression

The most common causes manifesting predominantly as prolonged fatigue (lasting 1 to 6 months) are

• Diabetes
• Hypothyroidism
• Sleep disturbances (eg, sleep apnea)
• Cancer

The most common causes manifesting predominantly as chronic fatigue (lasting more than 6 months) are

• Chronic fatigue syndrome
• Mood changes (eg, depression)
• Drugs
• Chronic weight loss
• Chronic fever or night sweating
• Generalized lymphadenopathy
• Muscle weakness or pain
• Serious non-fatigue symptoms (blood loss, Sever breathing problem, liver diseases , change of level of conciousness, suicidal ideation)
• Involvement of more than 1 organ system (eg, skin rashes plus joints pain)
• New or different headache or loss of vision, particularly with muscle pains, in an older adult
• Older age (eg, > 65 yr)

By  Dr. Fatemeh Aghanasiri, MD (MCC)