Symptoms and Signs of Interstitial Lung Disease

Interstitial Lung Disease Symptoms

Decreased lung function is the result of the inflammation present in the supporting interstitial tissues, which leads to scarring and thickening. This is because the thickened and stiff tissues cannot breathe as effectively as healthy lung tissue. Symptoms, therefore, are related to the reduced efficiency of breathing and corresponding reduced levels of oxygen in the blood.

The symptoms depend to a certain extent upon the exact cause of the condition, but shortness of breath and a dry cough are the most common symptoms. In most cases, these symptoms develop gradually. Signs of chronically reduced oxygen levels in the blood include clubbing (a painless enlargement of the fingertips) and an enlarged heart.

Interstitial lung disease can lead to serious long-term complications. Pulmonary hypertension, a type of high blood pressure that affects the arteries within the lungs, may develop. Ultimately, right-sided (the side of the heart that pumps blood back to the lungs to receive oxygen) heart failure may result (known as cor pulmonale). Respiratory failure is a potentially fatal long-term complication of interstitial lung disease.

Interstitial Lung Disease Causes

Interstitial lung disease is felt to be caused by a misdirected immune or healing reaction to a number of factors, including:

• infections of the lungs;
• toxins in the environment (such as asbestos, silica dust);
• certain medications (particularly some drugs used as chemotherapy for cancers);
• radiation therapy to the chest; and
• chronic autoimmune diseases: connective tissue diseases such as lupus, scleroderma, and rheumatoid arthritis

Sometimes, the process of inflammation and scarring of the interstitial tissues of the lungs develops in the absence of a known cause. When no cause can be identified, this is referred to as idiopathic (unknown cause) interstitial lung disease or idiopathic pulmonary fibrosis. Depending upon the location, severity, and pattern of lung involvement, the idiopathic interstitial lung diseases have been further subdivided into categories. Examples of different types of idiopathic interstitial lung disease include:

• usual interstitial pneumonitis (UIP),
• bronchiolitis obliterans with organizing pneumonia (BOOP),
• lymphocytic interstitial pneumonitis (LIP), and
• desquamative interstitial pneumonitis (DIP).