Pulmonary fibrosis (PF) is a respiratory disease characterized by the presence of scarred tissue in the lungs. The disease starts to cause the thickening and stiffening of the tissue, which ends up turning into fibrosis and causing difficulties in the lungs to properly transport the oxygen into the bloodstream. The lack of oxygen is responsible for symptoms like shortness of breath, a persistent dry and hacking cough, fatigue and weakness, discomfort in the chest, loss of appetite, unexplained weight loss, and clubbing of the fingers.

“It can be challenging to figure out what caused your pulmonary fibrosis. Sometimes doctors are able to identify one or more causes of your disease, but it is also common to end up without an answer, despite completing a large number of medical tests. Diseases where a specific cause is not identified are often called ‘idiopathic’ — meaning the cause is not identified or the disease occurs spontaneously,” according to the Pulmonary Fibrosis Foundation (PFF). The foundation adds that there is also idiopathic nonspecific interstitial pneumonia (NSIP), cryptogenic organizing pneumonia (COP), and sarcoidosis, in addition to idiopathic pulmonary fibrosis.

Pulmonary Fibrosis Associated with Autoimmune Diseases

Pulmonary fibrosis can be caused by an autoimmune disease such as rheumatoid arthritis or systemic scleroderma, or by certain muscle diseases including polymyositis, dermatomyositis, and anti-synthetase syndrome.

These types of conditions are also considered to be connective tissue diseases, collagen vascular diseases, or rheumatologic diseases which all affect the immune system. Due to these autoimmune diseases, the body’s own immune system can attack the lungs, causing inflammation and scarring.

Occupational and Environmental Exposure as a Cause for Pulmonary Fibrosis

Occupational and environmental exposure to toxic substances can cause irritation of the cells in the lungs and result in scarred tissue. In many cases, patients who develop pulmonary fibrosis were exposed to a wide variety of inorganic dust including asbestos, silica, coal dust, beryllium, or hard metal dusts.

In the case of environmental exposure, it is often related to organic dusts such as animal proteins, bacteria, and molds. These substances can cause the development of specific types of pulmonary fibrosis, which are known as “hypersensitivity pneumonitis.”

Pulmonary Fibrosis Related to Medication or Drugs

There are also medications and drugs that can cause lung damage and pulmonary fibrosis. Patients who undergo radiation therapy can suffer from it, depending on how much of the lung was exposed to radiation, the total amount of radiation administered, whether chemotherapy also was used, and the presence of underlying lung disease. Similarly, chemotherapy drugs designed to kill cancer cells, including methotrexate (Trexall) and cyclophosphamide (Cytoxan), can cause damage to lung tissue. Antiobiotics used to treat heart conditions like nitrofurantoin and sulfasalazine, as well as the seizure medication phenytoin, are also known to cause pulmonary fibrosis.

Impact of Genetics on Pulmonary Fibrosis Development

“Approximately 10-15 percent of those with an ‘idiopathic’ form of PF have another family member afflicted by the disease. This is called familial pulmonary fibrosis (FPF) or familial interstitial pneumonia (FIP). A number of genes and genetic variants have been identified that are associated with the development of pulmonary fibrosis, but frequently genetic tests are not performed when PF is diagnosed, as we are only just beginning to understand the significance of these genetic abnormalities,” according to the PFF. “It is important to discuss the potential risks and benefits of genetic testing with a qualified genetic counselor and your medical provider.”

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