MRCP2-4140

MRCP2-4140

A 57-year-old accountant is referred to the respiratory clinic by his General Practitioner with a 4-month history of a cough. He has no medical history of note, is a non-smoker and takes no regular medications. The patient describes a dry nocturnal cough with no sputum or haemoptysis and no other associated symptoms.

On examination, the patient has a body mass index (BMI) of 28 kg/m². Cardiovascular, respiratory and abdominal examinations are unremarkable. A chest x-ray is normal and a Forced Expiratory Volume in 1 second to Forced Vital Capacity ratio (FEV1/FVC) is calculated to be 0.62.

What would be your first line investigation choice?