Hypersensitive Pneumonitis Profile - Basic

Hypersensitivity pneumonitis (HP) previously known as extrinsic allergic alveolitis is an interstitial lung disease that is characterized by a complex immunological reaction of the lung parenchyma in response to repetitive inhalation and subsequent sensitization to a wide variety of inhaled organic dusts. HP is associated with progressive pulmonary disability, irreversible lung damage, and mortality in some cases. HP can be classified as Acute/Inflammatory (symptoms less than six months) and Chronic/Fibrotic (symptoms more than six months) based on clinical, radiologic and pathologic characteristics.

The name previously used for this condition, extrinsic allergic alveolitis, has been largely abandoned because inflammation involves more than just the alveoli and can extend to the bronchioles as well. The severity of the disease and clinical presentation varies depending on the quantity and type of inhaled antigen causing the condition. Numerous antigens have been found to cause HP. Exposures to the causative antigens can be associated with specific occupations or hobbies but can also occur in the home and general environment, some of which are:

• Bird or Pigeon Fancier’s Lung: Globally, this is the most commonly reported form of HP
• Farmer’s Lung: Caused by exposure to moldy hay, compost or grain stored in conditions of high humidity in the agricultural workplace

Humidifier/Sauna Taker’s Lung: HP secondary to occupational exposure to moldy water from heating/ventilation/air-conditioning systems

Associated Tests: 

Allergy - Adult (Comprehensive) Panel 

Allergy Screening 

Written by: Supriya Kulkarni, Lead-Content & Training

Reviewed by : Dr. Alap Christry M.D. AVP-Lab Operations & Scientific Business Head-Clinical Chemistry