What is the management approach for elevated white blood cell (WBC) count in patients with muscular dystrophy?

Management of Elevated White Blood Cell Count in Muscular Dystrophy

Elevated white blood cell count in patients with muscular dystrophy should be evaluated for underlying infection first, as it is not a typical feature of the disease itself, and any unexplained leukocytosis warrants investigation for secondary causes.

Assessment of Elevated WBC in Muscular Dystrophy Patients

Initial Evaluation

• Consider that muscular dystrophy itself does not typically cause leukocytosis
• Evaluate for common causes of elevated WBC:
  • Infection (most common cause requiring intervention)
  • Medication effect, particularly corticosteroids
  • Stress response (including respiratory distress)
  • Inflammation related to muscle breakdown

Specific Considerations in Muscular Dystrophy

Medication-Related Causes

• Corticosteroids (commonly used in muscular dystrophy treatment) can cause significant leukocytosis
  • Peak WBC elevation occurs approximately 48 hours after steroid administration
  • Mean increase of 4.84 × 10^9/L WBCs may be seen with high-dose steroids 1
  • Smaller increases (mean 1.7 × 10^9/L) with medium doses
  • Minimal increase (mean 0.3 × 10^9/L) with low doses

Infection Assessment

• Patients with muscular dystrophy are at increased risk for respiratory infections due to:
  • Weakened respiratory muscles
  • Impaired cough mechanism
  • Potential aspiration risk
• Signs of respiratory infection may be subtle in muscular dystrophy patients:
  • May not display typical labored breathing or accessory muscle use due to generalized weakness 2
  • Hypoxemia (saturations <95%) should prompt urgent assessment 2

Management Algorithm

Step 1: Determine Severity and Urgency

• If patient shows signs of respiratory distress:
  • Ensure CO2 levels are monitored
  • Low threshold for enhanced monitoring and critical care input
  • Consider arterial blood gas analysis to rule out hypercapnia 2
  • Urgent assessment by a respiratory specialist is recommended

Step 2: Identify Likely Cause

1. Medication review:

   • Check if patient is on corticosteroids (prednisone/prednisolone or deflazacort)
   • If recently started or dose increased, WBC elevation up to 4.84 × 10^9/L may be expected 1
   • Larger increases suggest other causes

2. Infection workup:

   • Complete blood count with differential
   • Blood cultures if febrile
   • Chest imaging (preferably CT rather than plain radiograph for better sensitivity)
   • Sputum culture if productive cough present
   • Urinalysis and urine culture

3. Other considerations:

   • Recent trauma or surgery
   • Emotional stress
   • Recent physical exertion

Step 3: Management Based on Cause

If Infection Identified:

• Initiate appropriate antimicrobial therapy based on suspected source
• For respiratory infections:
  • Ensure adequate airway clearance
  • Consider urgent assessment by physiotherapist with experience in airway clearance 2
  • Non-invasive ventilation (NIV) is the initial treatment of choice for respiratory infections 2
  • Regular physiotherapy with mechanical insufflator-exsufflator (MI-E) is often required 2

If Medication-Related:

• If WBC elevation is consistent with expected steroid effect:
  • Continue monitoring without intervention
  • Do not discontinue glucocorticoids prematurely as they remain cornerstone of treatment 3

If Stress-Related:

• Address underlying stressor if possible
• Monitor for resolution as stress diminishes

Special Considerations

Respiratory Management in Muscular Dystrophy

• Avoid excessive oxygen administration in isolation as it can worsen hypercapnia 2
• Target oxygen saturation range of 88%-92% in adults or above 92% for children 2
• High or increasing oxygen requirement should prompt urgent reassessment and consideration of NIV 2

Common Pitfalls to Avoid

1. Misinterpreting steroid-induced leukocytosis as infection
2. Overlooking subtle signs of respiratory compromise in muscular dystrophy patients
3. Delaying specialist respiratory input when needed
4. Excessive oxygen administration without ventilatory support
5. Failing to contact the patient's primary neuromuscular team for guidance 2

When to Consult Specialists

• Contact primary respiratory and neuromuscular teams as soon as practicable for any acute respiratory deterioration 2
• Consider hematology consultation if leukocytosis remains unexplained after initial workup
• Low threshold for critical care involvement with any signs of respiratory compromise

By following this systematic approach, clinicians can appropriately evaluate and manage elevated white blood cell counts in patients with muscular dystrophy, ensuring timely identification and treatment of potentially serious underlying conditions.