17th January 2024

Diagnosis

Firstly, a detailed history should be taken, particularly in relation to identifying if any confirmed exposure to a causative agent has occurred at any point. In two-thirds of cases, the allergen is never found but known exposure to a known causative agent makes this diagnosis likely alongside relevant clinical signs and symptoms.

Testing for sensitivity to known allergens is not always recommended, as false positive and negative results are common. The diagram below details the typical panel of tests ordered when working up a patient with suspected HP, alongside an explanation of expected findings in someone with this diagnosis.

Adapted from: Grammer, L. (2022) Hypersensitivity pneumonitis, Hypersensitivity pneumonitis – Symptoms, diagnosis and treatment | BMJ Best Practice. BMJ Best Practice. Available at: https://bestpractice.bmj.com/topics/en-gb/647 (Accessed: January 15, 2023).