This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System Pa 1, Subject name: Physiology
Pulmonary function abnormalities in interstitial lung disease include all of the following except - 
Select and explain. 
A. Reduced vital capacity, B. Reduced FEV1/FVC ratio, C. Reduced diffusion capacity, D. Reduced total lung capacity
B: Reduced FEV1/FVC ratio
Answer: B: Reduced FEV1/FVC ratio 
Explanation: Interstitial lung disease is a restrictive lung disease. In a restrictive lung disease, lung compliance or expansibility is decreased. Hence, vital capacity is reduced. Total lung capacity will also decrease. Diffusion capacity of respiratory membrane is reduced as the diffusion distance is increased in interstitial lung disease. Since VC is reduced, FEV1/FVC ratio is increased.