If FVC is decreased compared to predicted values, what condition is most likely indicated?

• A. Asthma
• B. Restrictive lung disease
• C. Normal pulmonary function
• D. Obstructive lung disease

Answer: (B)

When forced vital capacity (FVC) is decreased compared to predicted values, it is most indicative of restrictive lung disease. This condition is characterized by a reduction in lung volumes and often results from factors that limit lung expansion, such as fibrosis, pleural disease, or neuromuscular conditions. In restrictive lung disease, there is a notable decrease in total lung capacity, making it difficult for individuals to fully expand their lungs during inhalation, leading to a diminished FVC.

In contrast, asthma and obstructive lung disease typically manifest with normal or even increased FVC values but show abnormalities in other measurements, such as decreased forced expiratory volume (FEV1). Normal pulmonary function does not align with a decreased FVC, as it implies lung capacities are within expected limits. Therefore, a decreased FVC is clearly indicative of a restrictive process rather than these other conditions.