Diagnostic Tests for Idiopathic Pulmonary Fibrosis
By Dr. James H. Dauber
Medical history and general physical are taken during the initial visit.
Type of Study |
What is done and when |
Reason for Doing |
|---|---|---|
| Chest imaging studies | Involves taking chest x-rays or high-resolution CT (computed tomography) scans of the chest. Imaging studies are usually performed very early in the workup of IPF and are repeated as indicated. The CT should not be repeated too frequently because of higher radiation exposure compared to the chest x-ray. Both the chest x-ray and CT scan will require about 15-30 minutes of time. | Chest x-ray is a screening tool to assess for the cause of shortness of breath. It may be negative in early cases of IPF. CT scans assess extent of disease (changes in bronchial structure, scarring pattern throughout the lung) and are much more sensitive than the chest x-ray in detecting early disease. Both studies are used to assess for progression of disease |
| Pulmonary function test (PFT) | Involves breathing into a device called a spirometer to measure maximum breathing capacity. PFT’s require about 30 minutes to complete and require making the best effort possible which may cause some chest discomfort and coughing. TLC–total lung capacity(the amount of air in the lungs at maximal inspiration) FVC–forced vital capacity(the total amount of air that can be blown out on maximal expiration after taking a full breath in) FEV1–forced expiratory volume in the first second of the FVC maneuver DLco–diffusion capacity for carbon monoxide( an indirect measure for the transfer of oxygen from the lung into the blood) |
To measure the initial degree of lung function impairment and to monitor disease progression. These studies should be repeated routinely every 3 months to assess for progression or sooner if shortness of breath worsens. |
| Arterial blood gas analysis | Mearsurement of oxygen levels in the arterial blood. This requires blood directly obtained from an artery which is more painful than taking blood from a vein. This test is done during the intial evaluation and when symptoms worsen. It takes about 5-10 minutes to perform and is usually done with the PFT’s. | To determine the lung's ability to deliver oxygen to the body's tissues and whether supplemental oxygen is required at rest or with exertion to maintain a safe level of oxygen in the arterial blood. Arterial blood gas analyses are not routinely repeated but should be done again if symptoms worsen. |
| Exercise test | Involves walking on a treadmill, riding stationary bike or walking as far as possible for six minutes (Six minute walk test) while the amount of oxygen in the blood is monitored with a pulse oximeter. Pulse oximetry is a noninvasive method. These tests will take from 20-40 minutes and require maximal performance which may cause cough, shortness of breath and fatigue. | To determine how well the heart and lungs respond to the demands of physical activity and whether supplemental oxygen is needed to maintain a safe level of oxygen during activity. These studies will also detect progression of disease much earlier than do the radiographic studies and PFT’s. |
| Other laboratory tests | Urinalysis, full blood count, differential blood count, blood urea nitrogen, electrolytes, creatinine, liver function and, autoantibodies They require obtaining venous blood which should take just a few minutes and not be too painful. | To rule out other diseases, monitor changes in body functions over time that are related to the disease or its treatment |
| Lung biopsy | Taking a number of small samples of lung tissue through a bronchoscope or larger pieces of lung through a small incision in the chest with a thoracoscope. The transbronchial lung biopsy is an outpatient procedure with low risk that requires half a day. The tissue obtained is insufficient to make a diagnosis of IPF, but may exclude other diseases. The thoracoscopic biopsy is an inpatient procedure that requires general anesthesia but is the “gold standard” for confirming a diagnosis of IPF. | To directly examine lung tissue for a correct diagnosis of IPF, for measuring disease activity and risk for progression A thoracoscopic lung biopsy is not always necessary to confirm a diagnosis of IPF, though. |
Tests for connective tissue diseases such as rheumatoid arthritis, lupus, or scleroderma are done.
Bronchoalveolar Lavage maybe done to study the cells and check for signs of inflammation.
What Are the Risk Factors for IPF?
Learn more about the various risk factors for IPF ranging from age, environment, to family history.
Copyright © 2006 James H. Dauber, MD