A multiple step process is necessary to diagnose interstitial lung disease (ILD). Diagnosis begins with an in-depth look at family history, a review of any symptoms suggestive of connective tissue diseases, a listing of all current and former medications, and a review of any environmental and occupational exposures to dusts, gases, chemicals, pets (in particular birds), air conditioners and humidifiers.
Other procedures to help with diagnosis may include:
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A complete physical examination. Findings of crackling sounds in the lungs and changes in the skin, joints and fingernails can help direct further evaluation.
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A high resolution chest computed tomography (CT) scan. Results are usually abnormal and can sometimes help determine the type of ILD present.
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Pulmonary function tests. These lung function test results are usually abnormal with ILD. Your lung function may be checked before and after an inhaled bronchodilator treatment.
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Arterial blood gas. The arterial blood gas test measures the amount of oxygen and carbon dioxide in your blood. The results may be normal or show a reduced oxygen level.
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Exercise testing. Exercise tests may show a reduction in your oxygen level during activity.
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Bronchoscopy with bronchoalveolar lavage or biopsy. Bronchoscopy may be done to check for inflammatory cells in your lungs or sample small pieces of the lung to look for evidence of a specific ILD. Bronchoscopy involves inserting a tube through the nose into your trachea (windpipe) to see the airways. In bronchoalveolar lavage, a small amount of sterile saline is placed in one area of your lung and then withdrawn. This fluid contains cells that will be analyzed under the microscope. Small biopsy tools may be used through the bronchoscope if indicated.
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Surgical lung biopsy. In many cases of ILD, a surgical lung biopsy is needed to get enough lung tissue to make a specific diagnosis. This is often performed with the use of a thoracoscope that allows the surgeon to biopsy multiple areas of one lung through a few very small incisions.
