I have noticed that many people living with PF are frustrated by the scientific and medical community's lack of understanding about the causes of PF. I thought I would take a moment to let you know what we DO and DON'T know about the causes of PF. I will also help you try to figure out the cause of your PF (if a cause is known for your kind of PF).
Idiopathic forms of PF
First, let's address the frustrating "idiopathic" types of PF. We use the term "idiopathic" to describe disease without a known cause. As many of you know, "idiopathic pulmonary fibrosis" (also known as IPF) is only one of the many types of PF for which we don't know the cause. Doctors group these diseases of unknown cause into a category called "idiopathic interstitial pneumonias." There are many of them. I am not going to go into detail about each one. But, I will tell you two pieces of (hopefully) useful information.
(1) Many of these conditions are named after the appearance of your lung tissue under the microscope. Importantly, many of these lung biopsy appearances (which we call "patterns") can be seen in other types of PF of known cause (see later on about the "interstitial lung diseases of known cause or association.") So, just because your biopsy shows "NSIP" doesn't necessarily mean that you have idiopathic NSIP. You might have an "interstitial disease of known cause or association" with an NSIP pattern on your biopsy. Read on and then talk to your doctor for more information.
(2) All of the "idiopathic interstitial pneumonias" require a surgical biopsy of the lung to diagnose, with two exceptions: idiopathic pulmonary fibrosis and unclassifiable idiopathic interstitial pneumonia can in some cases be diagnosed without a biopsy.
Here is a list of the idiopathic interstitial pneumonias (and their abbreviations):
- Idiopathic Pulmonary Fibrosis (IPF)
- Idiopathic Non-specific Interstitial Pneumonia (idiopathic NSIP)
- Respiratory Bronchiolitis-interstitial lung disease (RB-ILD)
- Desquamative Interstitial Pneumonia (DIP)
- Cryptogenic Organizing Pneumonia (COP)
- Acute Interstitial Pneumonia (AIP)
- Idiopathic Pleuroparenchymal Fibroelastosis (IPPFE)
- Idiopathic Lymphoid Interstitial Pneumonia (Idiopathic LIP)
Unclassifiable Idiopathic Interstitial Pneumonia (Unclassifiable IIP)
There are other types of PF of unknown cause too. For example, pulmonary sarcoidosis and a number of more rare types of lung disease would also be called "idiopathic", even if they are not included in the "idiopathic interstitial pneumonia" category.
Interstitial Lung Disease of Known Cause of Association
There are a handful of types of PF for which we do know the cause – or at least we understand what might have triggered the disease. We call these diseases "interstitial lung diseases of known cause or association" (I know, ridiculously long). Here are five major categories of "interstitial lung diseases of known cause or association"
- Radiation therapy-induced
- Autoimmune disease (also called Connective Tissue Disease-ILD)
- Hypersensitivity pneumonitis (Environmental causes)
- Pneumoconioses (Occupational causes)
If you have been diagnosed with PF (or ILD), you and your doctor can work together to see if you have one of these "interstitial lung diseases of known cause or association." It's not too difficult, and you can start the process by asking yourself a few questions. I'll share with you the questions I ask my patients to sort out possible causes of their PF:
"Have you ever taken a medication to slow a fast heartbeat? Have you ever had atrial fibrillation ("A Fib") or had your heart shocked to stop an abnormal heart rhythm? Have you ever taken a medication called Amiodarone or Cordarone?"
Amiodarone (Cordarone) can cause ILD.
"Have you ever had urinary or prostate infections? Have you ever taken an antibiotic called nitrofurantoin, Macrobid, or Macrodantin?"
Nitrofurantoin can cause ILD.
"Have you ever taken methotrexate or received chemotherapy?"
Methotrexate and chemotherapy can cause ILD.
"Are there other medications you've taken for long periods of time in the past?"
Lung disease due to medications that you either take currently or have taken in the past can be looked up at www.pneumotox.com. Be warned: Many of the cases of lung disease on Pneumotox.com are NOT caused by medications – but when people develop a lung disease after taking a medication, doctors scratch their heads and wonder if the drug could have been responsible for the lung disease – but they can't really prove the link. Be sure to discuss your medications with your health care provider before you make any changes to your medical regimen – seriously, you could be harmed by stopping your medications.
This one is usually pretty obvious. Any history of radiation treatment to the chest for breast cancer, lymphoma, or another type of cancer can cause PF.
There are a variety of autoimmune diseases that can cause "Connective Tissue Disease-associated Interstitial Lung Disease" (also known as CTD-ILD). "Auto" means "self" – so autoimmune diseases are conditions in which your immune system attacks tissues and organs in your body. This can lead to inflammation, injury, and scarring in different organs. The lungs are often involved.
In my experience, the most common autoimmune diseases that cause PF are:
- Rheumatoid Arthritis (this is different and less common that Osteoarthritis)
- Scleroderma (now called Systemic Sclerosis)
- Anti-synthetase syndrome
- Sjögren's Syndrome.
Occasionally other types of autoimmune disease (such as Systemic Lupus Erythematosis, or "lupus") can cause PF. Certain types of blood vessel inflammation diseases (called "vasculitis") can also cause PF. Some people even develop an "idiopathic interstitial pneumonia" due to "autoimmunity" but without developing one of these specific autoimmune diseases. We now use the term "interstitial pneumonia with autoimmune features" (or "IPAF") to describe this condition. Many of these folks have "NSIP" on their biopsy (see above section on "idiopathic interstitial pneumonias") and can also (correctly) be diagnosed with idiopathic NSIP.
In addition to asking my patients if they have ever had one of the autoimmune diseases listed above, I ask my patients the following questions to sort out if they might have an autoimmune disease:
"Do you have pain, swelling, or stiffness in any of your joints?"
"Are your hands stiff when you wake up in the morning? How long does it last?" (an hour suggests autoimmune disease)
"Have you noticed any thickening or tightening on your fingers, hands, or neck?"
"Have you noticed any rash on your face, chest, or arms? Does it occur in areas exposed to the sun?"
"Do you suffer from heartburn? Do you occasionally have food come all the way up to your throat?
"Do you suffer from dryness of the eyes?"
"Do you suffer from dryness of the mouth?"
"Do your fingers sometimes turn white or red? Does cold weather make this worse?"
"Do you suffer from pain in your muscles in your arms or legs? How about weakness?"
Now, many of us have had one or more of these symptoms – so don't start to worry that you have an autoimmune disease because you've had some joint pains or a rash. But definitely talk to your health care provider about any symptoms you are experiencing --- your doctors can help you determine if you have an autoimmune disease.
If you break down the term Hypersensitivity Pneumonitis, you can see that it means your lungs are "too sensitive" to something. Usually the "somethings" are proteins from a living thing that you are breathing in – the most common culprits are proteins from mold spores, bacteria, and animals (particularly birds living indoors). Breathing these proteins triggers inflammation in the tiniest little airways in your lungs, followed by inflammation in the walls of the air sacs, and in some cases this leads to scarring.
Hypersensitivity Pneumonitis is a long medical term – let's call it "HP" for short. In my practice, I see a LOT of HP – about 25% of my patients who have any kind of PF have HP (another 25% have autoimmune diseases, and 25% have idiopathic pulmonary fibrosis). There are 3 critical tests that help doctors figure out if you have HP as the cause of your PF:
- Asking the right questions to identify a possible exposure to proteins you are breathing in (see below)
- Listening carefully to the lungs for a special kind of lung sounds (called an "inspiratory squeak") – Squeaks sounds just like you'd expect. Squeaky. Ask your doctor.
- Getting the right kind of CAT scan – in addition to the usual CAT scan performed when you take a deep breath and hold it, a 2nd CAT scan performed after you breath out is also important. With this kind of CAT scan, your doctor can look for "gas trapping," or pockets of air that get trapped in different parts of your lungs when you breathe out.
Here are the questions I ask my patients to figure out if they have HP:
"Do you have a forced air heating system in your home? In a prior home? In a second or vacation home? In your workplace? If so, how long have you been exposed to it? Does it have a humidification system? Has it ever been contaminated with mold?"
"Have you ever had any water in your basement or another part of your home? Have you ever had water damage in your home?"
"Are you aware of any mold in your home (outside of your shower)?"
"Do you use a hot tub on a regular basis?"
"Do you use a humidifier in your home?"
"Do you have any birds that live in your home currently or in the past? Do you spend time in someone else's home where birds live? Do you take care of birds in cages or coops currently or in the past?"
"Have you been exposed to renovation or construction?"
"Have you been exposed to farming or an agricultural setting?"
"What hobbies do you have?"
Remember – just because you might have been exposed to one of the above does not mean it was the cause of your PF. Lots of us have had water in our basements at some point. But be sure to bring this up with your doctor.
Pneumoconioses (Occupational causes)
Pneumoconioses are types of PF that result from exposures in the workplace. Here are just a few examples:
- Asbestosis (due to asbestos exposure)
- Coal Worker's Pneumoconiosis
- Hard Metal Lung Disease
- (there are many others)
I usually ask my patients about their current job and all prior jobs. I also ask whether you ever worked in the military (particularly with exposure to Navy shipyards or dusts, fumes, gases, vapors, or chemicals).
I also ask if you've ever had a job where you were exposed to dusts, fumes, vapors, or gases that you might have breathed in. I also ask about the following exposures:
- Coal Work
- Foundry Work
- Sand Blasting
- Heavy metals
- Factory work
Please talk to your doctor if you've had a job where you might have been exposed to one or more of these things.
If you do have an "interstitial lung disease of known cause or association," it is important to figure this out. We can sometimes treat you based on the factors that are triggering your disease:
- Remove exposure to harmful medications
- Treat autoimmune diseases (usually with a Rheumatologist)
- Remove exposure to mold, bacteria, birds, etc.
- Remove exposure to occupational triggers
If you have PF of unknown cause, please talk to your doctor to figure out if you might have an "interstitial lung disease of known cause or association."
You can always get more information about PF and where to get medical care from the Pulmonary Fibrosis Foundation: