Diagnosing asbestosis is complex, because it is a rare disease. When patients go to their primary care physician complaining of a persistent cough or shortness of breath, the doctor must first rule out more common illnesses such as asthma and pneumonia. Patients are then usually referred to a lung specialist or pulmonologist for additional testing.
However, even when a specialist sees the symptoms of asbestosis and signs of tissue scarring on imaging scans, this is only enough evidence to suggest some kind of lung scarring disease, referred to as pulmonary fibrosis or interstitial lung disease.
Many things can cause scarring in the lungs besides asbestos — radiation exposure, air pollutants and various autoimmune diseases — and in many cases, doctors never determine the exact cause.
Pinpointing asbestosis depends on the patient providing thorough medical and occupational histories that suggest high levels of asbestos exposure. A patient must report a history of asbestos exposure.
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Testing for Asbestosis
One of the first tools a doctor will use in the diagnostic process is a stethoscope, which allows them to listen to the lungs. Scarring causes the lungs to make a dry, crackling sound when the patient breathes.
The doctor typically also has the patient perform a pulmonary function test to determine how the lungs are functioning. The patient blows into an instrument called a spirometer, which measures how much air the lungs can hold and how well air flows in and out.
Not all patients with asbestosis have abnormal pulmonary function test results, but one of the key signs of the disease is evidence of restrictive lung disease, which includes a reduction in forced vital capacity, or the most air a patient can force from their lungs after a full inhalation. Pulmonary function tests often reveal reduced lung function because of restriction caused by scarring.
- Chest X-Ray
Scarred lung tissue appears more opaque on an X-ray. In advanced cases of asbestosis, lung tissue may have a honeycomb-like appearance.
- CT Scan
Doctors use computerized tomography (CT) scanning when X-ray results are unclear. CT scanning can also be used to regularly screen asbestos-exposed individuals, as these scans can sometimes detect asbestosis sooner than chest X-rays.
While evaluating imaging scans, the doctor can also check the pleural lining around the lungs for signs of asbestos exposure. Inhaling asbestos may lead to the formation of pleural plaques, which can support a diagnosis of asbestosis.
A 2022 study published in the International Journal of Medical Informatics reported on the increased diagnostic accuracy of a computer algorithm to identify asbestosis on imaging scans compared to a radiologist.
It is possible to examine a sample of lung tissue under a microscope to help confirm a diagnosis of asbestosis, but this is uncommon. Extracting a tissue sample requires an invasive bronchoscopy procedure, so doctors usually only recommend it as a last resort.
Establishing a History of Asbestos Exposure
Asbestosis is caused by inhaling asbestos. For a patient to be diagnosed with this disease, the patient’s history must reveal consistent exposure to asbestos for more than five years or a shorter period of extremely intense exposure. During their medical evaluation, the patient must discuss all sources of asbestos exposure with their doctor and identify the duration, intensity and circumstances under which the exposure occurred.
There’s no easy way to test whether you have been exposed to asbestos. If you know you worked or lived in conditions with a lot of asbestos dust many years ago, then you should talk to your doctor about cancer screening. The same applies if you lived or frequently visited the house of someone with regular exposure.
The long latency period of asbestosis is a key factor in diagnosing the disease. Depending on the level of exposure, asbestosis usually takes 20 years or more from the time of initial exposure to cause symptoms. If a patient develops symptoms within only a few years of being exposed to asbestos, doctors are likely to suspect other lung diseases.
Grades of Asbestosis Severity
- Grade 0
Scarring affects the walls of some of the passageways (bronchioles) leading to the lungs’ air sacs (alveoli).
- Grade 1
Scarring affects the walls of most bronchioles and some alveoli.
- Grade 2
Scarring affects most bronchioles and alveoli.
- Grade 3
Scarring is advanced and some alveoli are completely damaged.
- Grade 4
Lung has a honeycomb-like appearance because of pervasive scarring.