Steroid Use During Pulmonary Function Testing
Oral or systemic corticosteroids should be continued during pulmonary function testing (PFT), while inhaled corticosteroids can definitely be continued without affecting test results.
Rationale for Continuing Steroids During PFTs
Inhaled Corticosteroids
- Inhaled corticosteroids do not need to be discontinued before pulmonary function testing 1
- The British Thoracic Society (BTS) guidelines specifically list inhaled corticosteroids among "drugs that may be continued" during testing 1
- Inhaled steroids primarily act locally in the airways and do not significantly alter the mechanical properties of the lungs in a way that would invalidate PFT results
Systemic Corticosteroids
- Discontinuing systemic corticosteroids before PFTs could:
- Trigger disease exacerbation
- Lead to adrenal insufficiency in patients on long-term therapy
- Potentially worsen the underlying condition being evaluated
- Create confounding variables by changing the patient's baseline status
Important Considerations
Risk-Benefit Assessment
- For patients on chronic systemic corticosteroid therapy (e.g., for inflammatory/rheumatologic diseases), the risk/benefit ratio strongly favors continuing therapy rather than stopping for PFTs 1
- Abrupt discontinuation of steroids could lead to:
- Adrenal crisis
- Disease flare
- Respiratory deterioration
Specific Clinical Scenarios
Asthma Assessment
- When performing bronchodilator reversibility testing, baseline measurements should be taken while the patient is on their usual steroid therapy
- This provides the most clinically relevant information about the patient's current disease state and treatment response
Interstitial Lung Disease
- For patients with ILD on corticosteroids, maintaining therapy during PFTs provides the most accurate assessment of their current functional status 1
- Discontinuing steroids could potentially lead to acute worsening of inflammation and affect test results
Tuberculosis Testing Considerations
- While not directly related to PFTs, it's worth noting that corticosteroids can suppress T-cell function and potentially lead to false-negative tuberculin skin test results 2
- This is a separate consideration from PFT performance
Documentation Requirements
- Always document the patient's current medications, including steroid type, dose, and timing of last dose before the PFT
- This information is crucial for proper interpretation of results
Conclusion
Continuing steroid therapy during pulmonary function testing provides the most accurate assessment of a patient's current respiratory status while minimizing risks associated with medication discontinuation. This approach aligns with current clinical practice guidelines and prioritizes patient safety and test validity.