What is the initial workup for a 45-year-old male presenting with fatigue?

Initial Workup for Fatigue in a 45-Year-Old Male

The initial workup for a 45-year-old male presenting with fatigue should include a focused history, physical examination, and targeted laboratory testing consisting of a complete blood count, comprehensive metabolic panel, and thyroid-stimulating hormone level. 1

Assessment of Fatigue

Severity Assessment

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

Focused History

When evaluating fatigue, focus on:

1. Fatigue characteristics:

   • Onset (sudden vs. gradual)
   • Pattern (constant vs. intermittent)
   • Duration (acute vs. chronic)
   • Change over time
   • Factors that worsen or alleviate symptoms
   • Impact on daily functioning 2

2. Key contributing factors to assess:

   • Pain
   • Emotional distress (depression, anxiety)
   • Sleep disturbances
   • Nutritional status
   • Activity level
   • Alcohol/substance use
   • Medication side effects
   • Comorbidities 2

Physical Examination

The physical examination should focus on identifying common secondary causes of fatigue:

• Cardiopulmonary assessment
• Neurological examination
• Skin examination for signs of systemic disease
• Lymph node examination 1

Laboratory Testing

For moderate to severe fatigue (score 4-10), initial laboratory testing should include:

• Complete blood count (to assess for anemia)
• Comprehensive metabolic panel (to evaluate electrolytes, kidney and liver function)
• Thyroid-stimulating hormone (TSH) 2, 1

Additional testing should be guided by clinical suspicion based on history and physical examination findings.

Important Considerations

Limited Yield of Extensive Testing

It's important to note that laboratory studies affect management in only 5% of patients with fatigue, and if initial results are normal, repeat testing is generally not indicated 3. Studies have shown that extensive laboratory investigations have a low yield in discovering treatable physical disorders in patients with chronic fatigue 4.

Classification of Fatigue

Fatigue can be classified as:

1. Physiologic: Related to lifestyle factors
2. Secondary: Due to underlying medical conditions
3. Chronic: Persistent fatigue lasting ≥6 months 1

Common Pitfalls to Avoid

• Attributing fatigue solely to one cause without comprehensive evaluation
• Ordering excessive laboratory tests without clinical indications
• Failing to consider common causes like medications, anemia, or depression
• Missing serious underlying conditions like malignancy 2

Follow-up Planning

• Schedule regular follow-up visits rather than sporadic urgent appointments for effective long-term management 3
• Reassess fatigue levels using the standardized scale at follow-up visits
• Adjust treatment plans based on response 2

For persistent unexplained fatigue despite normal initial evaluation, consider referral to appropriate specialists based on predominant symptoms or suspected underlying conditions.