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Pulmonary Fibrosis Foundation

Pulmonary Fibrosis Foundation

How PF Is Diagnosed

How PF Is Diagnosed

What is the diagnostic process for PF? The Pulmonary Fibrosis Foundation gives a detailed explanation as part of its Disease Education Webinar Series.

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In its commitment to serving the PF community, the Pulmonary Fibrosis Foundation provides a detailed explanation of the process for diagnosing PF.

The roughly 30-minute webinar was presented by David Lederer, MD, MS of New York Presbyterian/ Columbia University as part of its Disease Education Webinar Series.

Dr. Lederer divides the diagnostic process into several sections: doctor visit clues, initial diagnostic steps, and establishing disease type.

Doctor Visit Clues

  • Breathlessness. Common symptoms include shortness of breath, which often first appears when exercising or climbing stairs; from walking quickly or frequent phone use as the disease progresses; and eventually with just routine activity and bending over.
  • Cough. Dry cough (no phlegm) is typical, as is post-nasal drip (mucus buildup in the throat).
  • Lung crackles. The Velcro-like sound a doctor will hear when listening to deep breathing with a stethoscope, which can indicate scar tissue and inflammation if the person is not suddenly ill (pneumonia, for instance) and does not have heart disease.

Initial Diagnostic Steps

If these three major clues are present, a doctor will start thinking about PF and order testing. Two tests are lung function and high-resolution CT scan of the chest, which may be ordered at the same time.

  • Lung function testing can involve multiple tests, but two tests that are more common are discussed.

1. Spirometry involves breathing through the mouth into a machine that measures air volume and speed of entry and exit when inhaling and exhaling. This is done during both regular breathing and after taking the deepest breath possible and blowing as hard and fast as one can. Three important results on a printout are forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and the FEV1/FVC ratio.

a. “One of the most important measures of disease severity,” FVC is the amount of air blown out after the deepest possible breath, reflecting how much air the lungs can hold. FVC will decrease as scar tissue builds, indicating less lung capacity and greater disease severity. In early disease, a person can have a normal FVC of over 80% of the expected amount for someone the same age and gender with normal lung function. (An example is shown in which a person’s test result in liters of air is just 48% of the reference amount.)

b. FEV1 is the amount of air exhaled in the first second of blowing out as hard and fast as possible, and is often lower than normal in PF. Normal FEV1 is over 80% of the expected amount. (In the example, FEV1 is just 51% of normal and usually close to FVC in a person with PF.)

c. FEV1/FVC ratio is the amount of air exhaled in the first second versus the total amount. Most people with PF have a normal ratio of greater than 70%, where most of the air is exhaled within the first second.

2. Diffusing capacity measures how much air is passing from the lungs into the bloodstream (in other words, how thick the walls of air sacs are inside the lungs). Diffusing capacity decreases as scarring increases since, even in early disease, it becomes harder to get oxygen into blood with air sac walls getting thicker and stiffer. A normal diffusing capacity is 70%-80% of expected value. (It is usually 30%-40% less than FVC in someone with PF.)


  • High-resolution computed tomography (HRCT) scans show inside the lungs, where scarring, inflammation and other changes may be seen. Black areas represent normal lung tissue, thick white lines indicate blood vessels, and lighter gray areas (typically near the edges of the lungs) indicate scar tissue. Besides fibrosis, scarring can go by many names such as “reticulation,” “honeycomb” (appearing as such), and “traction bronchiectasis.” The term “ground glass” means haziness, which could indicate inflammation, while “usual pattern of interstitial pneumonia” and “non-specific interstitial pneumonia” (NSIP) describe scarring location. Critically, the CT scan confirms the presence of PF.

Establishing Disease Type—Which Kind of PF?

  • Once PF has been established on a CT scan, a doctor will try to find a cause through health and work history plus blood testing. Known causes are drugs (example, certain chemotherapies); radiation to the chest (cancer treatment); environmental (called “hypersensitivity pneumonitis” or HP) from exposure to mold and birds, most commonly; autoimmune (“connective tissue disease-related”) in which the immune system attacks the lungs, often occurring with joint inflammation and skin changes, for example, such as in rheumatoid arthritis and scleroderma; and occupational (“pneumoconiosis”) from dusts, fibers, and fumes that can cause PF (example, asbestos, coal, silica). HP can sometimes be established with known exposures and certain CT scan findings, though a lung biopsy is sometimes needed. Clues to autoimmune disease-related PF include, for example, stiff, painful joints; rash; dry eyes and mouth; and skin tightening on the face and hands (a rheumatologist can often confirm without need for lung biopsy). Occupational clues include job history in mining, quarry work, heavy metals, or asbestos, for example (biopsy is sometimes needed to confirm).


  • If a cause cannot be found, the disease may be “idiopathic” (of unknown cause). There are many idiopathic subtypes, including IPF, idiopathic NSIP, and sarcoidosis, for example. In IPF, a CT scan is often enough for diagnosis if a typical visual pattern of usual interstitial pneumonia (UIP) is present and all other possibilities have been eliminated. In cases of “probable” UIP, a diagnosis can also usually be made without a lung biopsy, but sometimes it is needed to confirm. (This aligns with new IPF diagnostic guidelines published in 2018.)

Dr. Lederer advises this entire process, or at least the later stages, be done by a pulmonologist. A second opinion can be pursued at any of 68 Pulmonary Fibrosis Foundation Care Centers throughout the US.

The webinar can be found at:

The webinar can also be found on YouTube, where slides can be viewed in full screen:

To ask any questions or obtain slides from the presentation, contact the PFF Patient Communication Center at: or toll-free 844.825.5733

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