One of the primary causes of ILD is thought to be air-borne fungi particles. These may have been ejected into the air from such sources as hay, air conditioning vents put into use after the winter shut down without being properly cleaned and disinfected and bird droppings.
Other possible causes are inorganic dust (such as silica and hard metal dusts), organic dust like bacteria, animal proteins. Also gases, fumes, drugs, chemicals and other poisons.
Possible drugs and poisons are chemotherapeutic agents, antibiotics (rare) and radiation. Residue left by certain infections may also play a role in this disease. Two possibilities are Systemic Lupus Erythematosus and Rheumatoid Arthritis.
In making a diagnosis your pulmonary specialist will or should consider a careful and thorough medical history including environmental and occupational exposures to dusts, gases, chemicals, pets, air conditioners, and humidifiers. You probably will have a complete physical examination. A chest x-ray. X-ray results are usually abnormal but in as many as 10% of cases, may be normal.
Pulmonary Function Tests or PFT's. Results are nearly always abnormal for PFT's. The early tests will most likely be conducted before and after an inhaled bronchodilator treatment. You may or may not have an exercise test which includes an Arterial blood gas test. Usually an artery in the wrist is utilized and measurements may be normal or show decreased oxygen.
Often elusive, this disease can demand a further battery of tests. Like anything else the best proof is something you can see. To that end your doctor may perform or have performed a bronchoalveolar lavage. This is where a very thin bronchoscope is passed through the nose into the windpipe to get a good look at the airways. This instrument also has a device attached to the end which enables small tissue samples to be collected for scrutiny in a lab. If good samples are obtained positive disease identification may be arrived at. However, in a good many cases it is sometimes necessary to do open lung biopsy so that better samples can be obtained.
Though not a high risk operation by today standards, this procedure does require hospital stay and can have some discomfort associated with it. An accurate diagnosis is critical to treatment for each individual. ILD's progression can vary from person to person, and people respond differently to therapy. Therefore it is very important to have the specific diagnosis made along with the staging of the disease. Staging indicates how much of the affected tissue is inflamed and how much is scarred. Some other ILD disorders are hypersensitivity pneumonitis, eonsinophilic granuloma, sarcoidosis, chronic eosinophilic pneumonia, Wegener's granulomatosis, idiopathic pulmonary hemosiderosis, and bronchiolitis obliterans.