Pulmonary fibrosis diagnosis
Fact-checked by Diagnosing pulmonary fibrosis (PF), a disease marked by lung scarring (fibrosis) that makes it harder to breathe, can be challenging because its symptoms overlap with those of other lung and heart conditions.
There is no single test that can diagnose PF. Instead, doctors usually rely on a person’s symptoms, medical and family history, a physical examination, and a series of diagnostic tests to look for signs of the disease and rule out other possible causes.
Additional tests may help identify the underlying cause and specific type of PF, which helps guide treatment choices and provides information about a person’s long-term prognosis.
Because the diagnostic process can be complex, evaluation by a lung specialist (pulmonologist) who understands how PF is diagnosed can help reduce the risk of a misdiagnosis. While there is no cure for the disease, an early diagnosis of PF enables the start of treatments that make life with PF easier.
Symptoms that may lead to testing
The first step toward a PF diagnosis is usually the collection of a detailed medical history and physical examination. Symptoms of PF that could lead to further testing include:
- Shortness of breath, even with everyday activities
- Persistent, dry cough lasting lasted for several weeks or months
- Extreme fatigue
- Unintended weight loss
- Widening or rounding of the fingertips or toes (clubbing)
During the physical exam, a doctor may listen to the lungs for fine crackling sounds, sometimes described as resembling Velcro being pulled apart. The clinician may also check for clubbing and signs of low blood oxygen, such as a bluish tint to the lips or fingernails.
The doctors will also ask about factors that could help identify the cause of any lung changes, including:
- Smoking history
- Occupational and environmental exposures, such as dust, chemicals, or mold
- Family history of PF or other lung diseases
- Current and previous medication use
- Autoimmune diseases or other health issues that may affect the lungs
This information helps doctors understand an individual’s risk of PF and give clues about its possible cause if the condition is suspected. If signs and symptoms of PF or another lung disease are present, additional diagnostic tests for PF and referral to a lung specialist will be necessary.
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| Tests | What they look for |
|---|---|
| Medical history and physical exam | Symptoms, family history, environmental or occupational exposures, medication use, crackling sounds in the lungs, and other clues to possible causes of lung scarring |
| Imaging tests | Signs of lung scarring, inflammation, and patterns that may help identify the type of PF |
| Lung function tests | How well the lungs move air and transfer gas into the bloodstream |
| Exercise and oxygen tests | Whether blood oxygen levels drop during activity and how well a person tolerates physical exertion |
| Blood tests | Signs of autoimmune disease, possible infections, and other clues that may help identify the cause of lung damage or rule out other conditions |
| Bronchoscopy and lung biopsy | Samples of fluid or lung tissue that may help identify infection, inflammation, or specific patterns of lung damage when other tests do not provide a clear diagnosis |
Imaging tests
Imaging tests allow doctors to examine the lungs for signs of scarring, inflammation, and other abnormalities. Such tests can help identify signs consistent with PF and rule out other lung conditions. These may include:
- Chest X-rays: These are quick and inexpensive scans that can reveal changes consistent with PF or another lung problem. However, they may miss early or subtle lung changes, and may not provide details on the pattern of fibrosis to help identify a possible cause.
- High-resolution CT scan (HRCT): This scan provides more detailed images of the lungs and is an important test for diagnosing PF. An HRCT scan may reveal lung scarring, which may appear as a honeycomb pattern in some people. It may also provide clues as to the type of PF a person has.
An echocardiogram, or a heart ultrasound, may also be used to investigate pulmonary hypertension or other heart problems that can occur alongside PF.
Lung function and exercise tests
If PF or another lung disease is suspected, patients will undergo pulmonary function tests that measure how well the lungs work. Among these short, noninvasive tests are:
- Spirometry: This test measures the amount of air a person can breathe in and out, and how fast they can blow air out of their lungs.
- Lung volume testing: This test measures how much air the lungs can hold.
- Lung diffusion testing, also called the DLCO test: This test is used to measure how well gas moves between the lungs and the blood.
- Pulse oximetry: This is an oxygen assessment test that estimates the amount of oxygen in the blood via a small device, called a pulse oximeter, placed on the fingertip.
- Exercise testing: This test monitors heart and lung function while a person walks or runs on a treadmill or stationary bike.
- Arterial blood gas testing: This test measures the amount of oxygen and carbon dioxide in the bloodstream using a small blood sample taken from an artery.
A common exercise assessment is the six-minute walk test for PF, which measures how far a person can walk on a flat surface in six minutes. During the test, the clinician may also monitor oxygen levels, breathing, and heart rate.
These tests help doctors understand the extent of lung impairment and track changes over time. In PF, as scar tissue increasingly interferes with the lungs’ ability to hold air, performance on these tests is progressively impaired at advancing disease stages.
Blood tests and other laboratory work
There is no blood test that can diagnose PF. But such tests are important for ruling out other conditions and, once a diagnosis is made, identifying the possible causes of the lung disease. Specifically, blood tests can assess:
- General functioning of the liver, kidneys, and other organs
- Whether there are antibodies linked to autoimmune diseases
- Any possible infections
In some cases, especially for an idiopathic pulmonary fibrosis diagnosis, a blood sample may also be collected for genetic testing to look for mutations in certain risk genes. This is particularly likely if a person has a family history of PF or other lung diseases.
Additional tests that may be needed
If imaging, lung function tests, and blood work are not sufficient to determine the cause of a person’s symptoms, doctors may recommend more invasive PF testing to help establish a diagnosis.
This often involves collecting a sample of tissue or fluid from the lungs and analyzing it in the lab for signs of PF. There are two ways this might be done:
- Bronchoscopy: In this procedure, a thin, flexible tube with a camera attached, called a bronchoscope, is inserted into the airways via the nose or throat. A doctor may perform a bronchoalveolar lavage, in which saltwater is injected into the lungs through the bronchoscope. That fluid, now containing cells and microbes from the lungs, is suctioned back up for analysis.
- Lung biopsy: A more invasive procedure, this test requires the collection of a small sample of lung tissue, which is then examined under a microscope. A lung biopsy may be performed using video-assisted thoracoscopic surgery (VATS), in which small incisions are made in the chest and a camera is used to guide tissue collection. However, there are cases in which lung tissue can be collected with a bronchoscope.
Direct analysis of lung tissue samples can reveal hallmarks of PF that aren’t clearly visible on imaging tests. However, because these procedures are invasive and carry risks, doctors weigh the potential benefits against those risks in deciding whether to use them.
Pulmonary Fibrosis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
