What diagnostic tests are recommended for confirming hypersensitivity pneumonitis in a primary care setting?

In a primary care setting, there are no specific diagnostic tests recommended to definitively confirm hypersensitivity pneumonitis (HP). Initial assessment should focus on a detailed clinical history, including environmental and occupational exposures, and a clinical examination to identify features suggestive of HP. Basic investigations such as chest X-ray and lung function tests (spirometry and gas transfer) may be performed to assess lung involvement but are not diagnostic for HP. If hypersensitivity pneumonitis is suspected, referral to secondary care for specialist assessment is essential, where high-resolution computed tomography (HRCT) of the thorax and multidisciplinary team evaluation are used to confirm the diagnosis. More invasive tests such as bronchoalveolar lavage or lung biopsy are considered only in specialist settings if the diagnosis remains uncertain after non-invasive assessments.

Summary of recommended approach in primary care:

• Take a detailed history focusing on exposure to potential antigens.
• Perform clinical examination and basic blood tests to exclude other diagnoses.
• Order chest X-ray and lung function tests as initial investigations.
• Refer promptly to respiratory specialists for further evaluation including HRCT and multidisciplinary team review.

This approach aligns with the NICE guideline on idiopathic pulmonary fibrosis and interstitial lung diseases, which recommends specialist involvement for diagnosis confirmation and use of advanced imaging and pathology when needed ¹.