What is the initial workup for fatigue?

Initial Workup for Fatigue

The initial workup for fatigue should include a focused history, physical examination, and targeted laboratory studies including complete blood count, comprehensive metabolic panel, and thyroid function tests. 1, 2

Assessment Algorithm

Step 1: Quantify Fatigue Severity

• Use a 0-10 numeric rating scale:
  • 0: No fatigue
  • 1-3: Mild fatigue (requires education only)
  • 4-6: Moderate fatigue (requires evaluation)
  • 7-10: Severe fatigue (requires prompt evaluation) 2

Step 2: Focused History

• Document specific characteristics:
  • Onset, pattern, and duration
  • Change over time
  • Associated or alleviating factors 1
• Assess for treatable contributing factors:
  • Medications (particularly sleep aids, pain medications, antiemetics)
  • Alcohol/substance use
  • Nutritional issues (weight/caloric intake changes)
  • Decreased functional status or activity level
  • Sleep patterns and disorders 1, 2

Step 3: Physical Examination

Focus on:

• Cardiopulmonary system
• Neurologic assessment
• Skin examination 3
• Signs of anemia or infection
• Evidence of endocrine disorders

Step 4: Laboratory Evaluation

Based on history and physical findings, consider:

• Complete blood count with differential
• Comprehensive metabolic panel (electrolytes, hepatic and renal function)
• Thyroid-stimulating hormone (TSH) 1, 2
• Consider inflammatory markers (ESR, CRP) if indicated 2

Classification of Fatigue

Fatigue can be classified into three main categories, which helps direct management:

1. Physiologic fatigue: Related to lifestyle factors, can be addressed through proper sleep hygiene, balanced diet, and appropriate energy expenditure 3

2. Secondary fatigue: Due to underlying medical conditions that require specific treatment 3

3. Chronic fatigue: Persistent fatigue lasting ≥6 months, including conditions like myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) 3

Important Considerations

• Laboratory studies affect management in only 5% of patients with fatigue. If initial results are normal, repeat testing is generally not indicated 4

• Be alert for warning signs of serious underlying conditions requiring urgent evaluation:

  • Unexplained weight loss
  • Fever
  • Localized pain
  • Abnormal physical findings
  • Severe fatigue (7-10/10) 2

• Fatigue is rarely an isolated symptom; a multisymptom screening tool may have greater clinical utility 1

• Consider post-exertional malaise as a key symptom that may indicate ME/CFS, particularly in the post-COVID context 3

Common Pitfalls to Avoid

• Failing to quantify fatigue severity, which helps determine urgency and extent of evaluation
• Overlooking psychological factors such as depression and anxiety 2
• Relying solely on pharmacologic interventions rather than incorporating lifestyle modifications 2
• Recommending increased exercise for all patients with fatigue (can worsen symptoms in ME/CFS) 3
• Missing medication side effects as a common cause of fatigue
• Failing to schedule regular follow-up visits to monitor progress 4