What is the workup for post-exertional fatigue?

Workup for Post-Exertional Fatigue

A comprehensive workup for post-exertional fatigue should include quantification of fatigue severity on a 0-10 scale, laboratory studies including complete blood count, comprehensive metabolic panel, thyroid function tests, and targeted cardiac evaluation when indicated. 1

Initial Assessment

Fatigue Severity Quantification

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

Focused History

• Document specific symptoms experienced after exertion:

  • Cognitive dysfunction (brain fog, difficulty concentrating) 2
  • Decrease in functional capacity 2
  • Sleep disturbances 3
  • Headaches 3
  • Muscle pain 3
  • Flu-like symptoms 3

• Determine onset pattern and duration of post-exertional symptoms:

  • Immediate vs. delayed onset (11% report consistent delay of ≥24 hours) 3
  • Duration of symptoms (84% experience symptoms for ≥24 hours) 3
  • Triggers (physical exertion, cognitive exertion, emotional distress) 3

Laboratory Studies

Essential Laboratory Tests

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

Additional Laboratory Tests

• Fasting blood glucose or glycohemoglobin 1
• Lipid profile 1
• Serum calcium and magnesium 1
• Urinalysis 1

Cardiac Evaluation

• 12-lead electrocardiogram for patients with cardiac symptoms 1
• Consider echocardiography if cardiac dysfunction is suspected 1
• Chest radiograph (PA and lateral) for patients with respiratory symptoms 1

Exercise Testing

• Consider cardiopulmonary exercise testing (CPET) to:
  • Evaluate cardiovascular response to exercise 4
  • Document post-exertional symptom exacerbation 5
  • Use Borg scale of perceived exertion to assess fatigue level during testing 4

Differential Diagnosis Considerations

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

• Post-exertional malaise is the hallmark symptom 5
• Key diagnostic indicators:
  • Presence of at least two symptoms post-exertion (cognitive dysfunction, decline in function) 2
  • Symptoms persisting for ≥24 hours after exertion 3
  • Multiple symptom domains affected (cognitive, sleep, pain, inflammatory) 3

Post-Stroke Fatigue

• Common sequela affecting at least half of stroke survivors 4
• Evaluate for:
  • Depression (common but distinct from fatigue) 4
  • Sleep disorders (sleep apnea, nighttime disturbances, daytime sleepiness) 4
  • Impact on rehabilitation participation 4

Cancer-Related Fatigue

• Evaluate using ICD-10 criteria for cancer-related fatigue 4:
  • Six or more symptoms present daily during same 2-week period
  • Significant fatigue disproportionate to activity level
  • Clinically significant distress or functional impairment
  • Evidence that symptoms are consequence of cancer or treatment
  • Not primarily due to psychiatric disorders

Management Approach

Non-Pharmacologic Interventions

• Structured exercise program with gradual progression 1:

  • Start with low-level activities
  • Include both aerobic and resistance exercises
  • Adjust intensity based on fatigue severity

• For moderate fatigue (4-6/10):

  • Reduce training volume to 5-6 hours weekly 1
  • Focus on shorter, less intense sessions 1
  • Prioritize quality over quantity 1

• Energy conservation strategies:

  • Schedule activities during peak energy times 1
  • Delegate non-essential tasks 1
  • Use labor-saving devices 1

Monitoring and Follow-up

• Regularly reassess fatigue levels 1
• Monitor for warning signs of excessive training load:
  • Inability to complete planned workouts
  • Breathing difficulty
  • Feeling faint or nauseous after exercise
  • Persistent fatigue
  • Sleep disturbances
  • Joint pain or discomfort 1

Common Pitfalls to Avoid

• Ignoring psychological factors (depression, anxiety) 1
• Relying solely on pharmacologic interventions 1
• Failing to recognize post-exertional malaise as distinct from general fatigue 5
• Overlooking delayed onset of post-exertional symptoms 3
• Inadequate monitoring of symptom patterns following exertion 1