How is Asbestosis Diagnosed?

Asbestosis, a form of pneumoconiosis, is a serious, chronic, progressive, non-cancerous respiratory disease. It is caused by breathing asbestos dust and generally affects individuals who have had prolonged contact with asbestos. The inhaled asbestos fibers settle deep in the lungs, where the cause scarring, or fibrosis, that results in shortness of breath and a dry, crackling sound in the lungs while inhaling. In advanced cases, asbestosis may cause cardiac failure. In most cases the symptoms of asbestosis become apparent decades after the exposure to asbestos occurred.

In diagnosing asbestosis, it is important for a doctor to know about the patient's history of asbestos exposure both at work and at home. Information about the length of asbestos exposure, the use (or lack) of protective clothing and respiratory dust masks, and whether co-workers or other household members have been diagnosed with asbestos-related diseases may also help to determine whether asbestosis is likely.

In the physical examination, a doctor using a stethoscope placed over the lungs will listen for abnormal sounds called basal crackles or persistent, high-pitched sounds that are characteristic of asbestosis. The doctor will also look for clubbed fingers, which often indicate the presence of a lung disorder.

Since the lung tissue scarring of asbestosis makes it difficult for the lungs to expand and contract and reduces the rate at which the lungs transfer oxygen to the blood, pulmonary function tests can be used to help diagnose the disease. In one such test, the patient blows into a spirometer, which is a device that helps determine lung capacity and lung and chest wall mechanics. Other tests measure how efficient the lungs are at transferring oxygen from the air into the blood. In addition, blood tests can be used to measure concentrations of oxygen and carbon dioxide.

In a person who has a history of exposure to asbestos, a doctor sometimes can diagnose asbestosis with a chest x-ray. An x-ray may show small, irregular, opaque areas usually in the lower lobes of the lungs; shadows or spots on the lungs; or an indistinct or shaggy outline of the heart that suggests the presence of asbestosis. When pleural plaques are caused by asbestos exposure, they often contain calcium, which makes them easily visible on x-rays. However, x-rays are limited in detecting early asbestosis as they sometime yield false positives for smokers as well as false negatives.

A computed tomography or CT scan may be more helpful in diagnosis asbestosis than the chest x-ray, particularly in those cases in which the x-ray is ambiguous or if the patient has a normal chest x-ray. A CT scan can help detect asbestosis in the early stages, and it can also show the flat, raised patches associated with advanced asbestosis.

If the chest x-ray shows a tumor of the pleura, the doctor may order a biopsy (the removal of a small piece of tissue so it can be examined under a microscope) to determine if the patient has cancer rather than or in addition to asbestosis. Alternatively, a needle may be used to remove some of the fluid around the lungs for analysis in a procedure called thoracentesis. A pleural biopsy, however, is usually more accurate than thoracentesis.

'How is Asbestosis Diagnosed?' Resources:
  1. O'Reilly, Katherine M.A., et al. American Family Physician. Vol. 75, No.5, March 1, 2007. "Asbestos-Related Lung Disease"
  2. U.S. Environmental Protection Agency. "The Asbestos Informer".
    Accessed: 13 August 2007
  3. Mayo Clinic. "Asbestosis: Screening and Diagnosis".
    Accessed: 13 August 2007
  4. Merck Manuals Online Medical Library. "Asbestosis".
    Accessed: 13 August 2007
  5. Asbestos Network. "Asbestosis Diagnosis".
    Accessed: 13 August 2007
  6. Health-Cares.net. "How is Asbestosis Diagnosed?".
    Accessed: 13 August 2007
  7. Mesothelioma & Asbestos Awareness Center. "Asbestosis Diagnosis".
    Accessed: 13 August 2007