Fatigue is a common complaint characterized by a persistent feeling of tiredness, lack of energy, or exhaustion that interferes with daily activities. It can be physical, mental, or both, and may have various underlying causes.

Definition

Fatigue is typically defined as:

• A subjective feeling of tiredness or exhaustion
• Decreased capacity for physical or mental work
• Impaired ability to perform daily activities
• Lasting for at least one month, though chronic fatigue lasts 6 months or longer

Etiology

Medical Causes

• Endocrine disorders (e.g., hypothyroidism, diabetes)
• Infections (e.g., viral illnesses, chronic infections like HIV)
• Anemia or iron deficiency
• Heart and lung conditions (e.g., heart failure, COPD)
• Autoimmune disorders (e.g., lupus, rheumatoid arthritis)
• Cancer and cancer treatments
• Sleep disorders (e.g., sleep apnea, insomnia)
• Chronic pain conditions

Lifestyle Factors

• Poor sleep habits or insufficient sleep
• Lack of regular exercise
• Unhealthy diet
• Alcohol or drug use
• Excessive caffeine intake

Psychological Causes

• Depression
• Anxiety disorders
• Stress
• Emotional exhaustion or burnout

Medications

• Antidepressants
• Antihistamines
• Beta-blockers
• Statins
• Some pain medications

Diagnostic Approach

• Comprehensive medical history
  • Duration and onset of fatigue
  • Associated symptoms
  • Sleep patterns
  • Medication review
  • Lifestyle factors
• Physical examination
  • General appearance
  • Vital signs
  • Systemic examination for signs of underlying conditions
• Laboratory tests
  • Complete blood count
  • Thyroid function tests
  • Fasting glucose
  • Liver and kidney function tests
  • Erythrocyte sedimentation rate or C-reactive protein
• Additional tests based on clinical suspicion
  • Sleep studies
  • Hormone level tests
  • Autoimmune markers
  • Imaging studies
• Psychological assessment
  • Screening for depression and anxiety

It’s important to note that in about one-third of cases, no specific cause of fatigue is identified. Management often involves addressing any underlying conditions, improving sleep hygiene, increasing physical activity, and providing psychological support as needed.