Spirometry Interpretation: Normal Lung Function
Your spirometry results are normal and do not indicate obstructive lung disease. With an FEV1/FVC ratio of 78% (which exceeds the diagnostic threshold of 70%), FVC at 102% predicted, and FEV1 at 92% predicted, these values fall within the expected range for healthy lung function.
Why This is Not Obstructive Disease
The FEV1/FVC ratio of 78% is above the 70% threshold required to diagnose airflow obstruction - multiple guidelines consistently define obstruction as FEV1/FVC <70%, and your ratio exceeds this cutoff 1.
Both FEV1 (92% predicted) and FVC (102% predicted) are within normal limits - these values indicate preserved lung volumes and airflow capacity 1.
The pattern does not meet criteria for any severity classification of COPD - even mild COPD requires FEV1/FVC <70% as the fundamental diagnostic criterion 1, 2.
Clinical Significance
An FEV1/FVC ratio >70% with normal FVC excludes obstructive lung disease - this pattern indicates the airways are not narrowed and air can be expelled normally from the lungs 1.
The slightly reduced FEV1 (92% vs 102% FVC) is within normal biological variation - FEV1 values ≥80% predicted are considered normal when the FEV1/FVC ratio is preserved 1.
Important Caveats
If respiratory symptoms are present despite normal spirometry, consider alternative diagnoses - conditions such as exercise-induced bronchoconstriction, early interstitial lung disease, or cardiac causes may require additional testing beyond baseline spirometry 1, 3.
The fixed 70% threshold may underdiagnose obstruction in younger adults - however, your ratio of 78% provides substantial margin above this threshold, making false-negative diagnosis unlikely 1, 4.
Serial measurements over time are more informative than a single test - if symptoms develop, repeat spirometry can detect early changes in lung function 1.