17th February 2025

A 20-year-old man presents to his GP with intermittent shortness of breath on exertion and nocturnal cough.

A 20-year-old man presents to his GP with intermittent shortness of breath on exertion and nocturnal cough. His past medical history is hayfever and type 1 diabetes. He smokes around 5 cigarettes a day. His GP suggests a salbutamol inhaler and a trial of inhaled corticosteroids. After six weeks of treatment he has ongoing symptoms, so his GP arranges spirometry with reversibility testing which show an FEV/FVC of < 0.7 and an FEV1 of 2.9 L pre-bronchodilator, which improves to 3.5 L post-bronchodilator. What is the most likely diagnosis?