Which initial investigations should I perform for a patient with suspected interstitial lung disease?

For a patient with suspected interstitial lung disease (ILD), the initial investigations should include:

• Detailed history and clinical examination to identify clinical features suggestive of ILD and to exclude alternative diagnoses such as environmental, occupational exposures, connective tissue diseases, or drug-induced lung disease.
• Blood tests to help exclude alternative diagnoses and associated conditions.
• Lung function testing, including spirometry and gas transfer (diffusing capacity for carbon monoxide, TLCO), to assess lung function and identify restrictive patterns.
• Chest X-ray as a baseline imaging to review lung abnormalities.
• High-resolution computed tomography (HRCT) of the thorax to provide detailed imaging for diagnosis and assessment of ILD.

If these initial investigations do not yield a confident diagnosis, further evaluation by a multidisciplinary team and consideration of bronchoalveolar lavage, transbronchial biopsy, or surgical lung biopsy may be required.

These recommendations are based on NICE guideline CG163 on idiopathic pulmonary fibrosis and interstitial lung disease diagnosis and management ¹.