This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Interstitial Lung Disease, Subject name: Medicine
Which pattern is seen in pulmonary function tests in a patient with interstitial lung disease? 
Select and explain. 
A. FEV1/FVC ratio increases and DLCO increases, B. FEV1/FVC ratio increases and DLCO decreases, C. FEV1/FVC ratio decreases and DLCO decreases, D. FEV1/FVC ratio decreases and DLCO increases
B: FEV1/FVC ratio increases and DLCO decreases
Answer: B: FEV1/FVC ratio increases and DLCO decreases 
Explanation: Pulmonary function tests In PFT,Airway narrowing,lung volume and gas exchange capacity are quantified and compared with normal values adjusted for age,gender,height,etc. Most forms of ILD will show restrictive pattern on PFT. Restrictive deficit TLC(Total lung capacity) Reduced FEV1(Forced expiratory volume in 1 sec) Symmetrically reduced FVC(Forced vital capacity) Reduced DLCO(Diffusing capacity of the lung for carbon monoxide) Reduced FEV1/FVC ratio Normal or increased characteristically >0.7 Approach to pulmonary function test interpretation: