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.
There are many forms of pulmonary fibrosis that are idiopathic. The one that many people have heard of is “idiopathic pulmonary fibrosis” or IPF, but there are many others. A few examples are:
- Idiopathic nonspecific interstitial pneumonia (NSIP)
- Cryptogenic organizing pneumonia (COP)
When the cause of PF is known, if often falls into one of these categories:
Autoimmune diseases are also called connective tissue diseases, collagen vascular diseases, or rheumatologic diseases. “Auto” means “self” and “immune” refers to your immune system. With autoimmune diseases, your own immune system is attacking your lung. If you have an autoimmune disease, your immune system can cause inflammation and scarring in the lungs. Examples of autoimmune diseases that can cause PF include:
- Rheumatoid arthritis
- Scleroderma (now called “systemic sclerosis”)
- Certain muscle diseases (polymyositis, dermatomyositis, and the anti-synthetase syndrome)
Pulmonary fibrosis can develop after significant exposure to a wide variety of inorganic dusts, including asbestos, silica, coal dust, beryllium, hard metal dusts.
Organic dusts, including animal proteins, bacteria, and molds, can also contribute to the development of some types of PF. Diseases caused by inhaled organic dusts are often called “hypersensitivity pneumonitis”. Exposure to radiation can also contribute to the risk of PF.
Drug Induced or Medication exposures
Some medications have been linked to the development of PF, including drugs used to treat:
- Infections (nitrofurantoin, sulfasalazine)
- Heart disease (amiodarone, propranolol)
- Seizures (phenytoin)
- Cancer (methotrexate, bleomycin, oxaliplatin, radiation therapy)
Approximately 10-15% 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 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. It is important to discuss the potential risks and benefits of genetic testing with a qualified genetic counselor and your medical provider. To speak with a Certified Genetic Counselor free of charge, contact Janet Talbert, MS, CGC at 800.423.8891, extension 1097.
CLASSIFICATION OF COMMON INTERSTITIAL LUNG DISEASES
The most common symptoms of PF are cough and shortness of breath. Symptoms may be mild or even absent early in the disease process. As the lungs develop more scar tissue, symptoms worsen. Shortness of breath initially occurs with exercise, but as the disease progresses patients may become breathless while taking part in everyday activities, such as showering, getting dressed, speaking on the phone, or even eating.
Due to a lack of oxygen in the blood, some people with idiopathic pulmonary fibrosis may also have “clubbing” of the fingertips. Clubbing is a thickening of the flesh under the fingernails, causing the nails to curve downward. It is not specific to IPF and occurs in other diseases of the lungs, heart, and liver, and can also be present at birth.
Other common symptoms of pulmonary fibrosis include:
- Chronic dry, hacking cough
- Fatigue and weakness
- Discomfort in the chest
- Loss of appetite
- Unexplained weight loss