Sarcoidosis - Tests Used For Diagnosis Part 1
It is important to diagnose sarcoidosis in people who are suspected of having this disease - the effects of sarcoidosis can range from non-harmful to life threatening.
Overview - Diagnosing Sarcoidosis
In many cases a doctor will perform a physical examination and review a patients medical history. Additional tests usually include blood tests, chest x ray and breathing tests. Many people displaying sarcoidosis symptoms are referred by their doctor to a pulmonologist (lung physician) - the lungs are an organ often affected by sarcoidosis.
Despite the number of tests which can be used a biopsy is the only reliable method when diagnosing sarcoidosis. A biopsy is a test which uses a sample of tissue taken from the affected area. The tissue is then tested for a disease. As sarcoidosis is a disease which affects the whole body, not just one organ, a tissue sample is usually taken from an accessible area of the body. Simple skin or conjunctival biopsy samples are normally taken under local anesthetic in a doctors surgery - the conjunctiva is a membrane which lines the eyelids inner surface.
Sarcoidosis Tests & Procedures
The tests and procedures below help diagnose sarcoidosis - they can also be used to assess and monitor the disease during and after treatment.
- Physical Examination
- Usually performed by the patients regular doctor who will look for external sarcoidosis symptoms. These include:
- red bumps on the skin
- redness in the eyes
- swollen lymph nodes
The doctor will look for other possible causes of these symptoms during the examination.
- Blood Tests
Blood tests are used to measure the blood levels of proteins such as ACE (angiotensin converting enzyme). ACE is made by the cells in the granulomas. However, elevated or high levels of blood ACE does not always indicate sarcoidosis - other tests to diagnose sarcoidosise are also used.
Blood tests may also show elevated calcium levels and abnormalities in the liver, kidneys and bone marrow (organs which can be affected by sarcoidosis).
- Chest X Ray
Chest x rays are frequently used to test for sarcoidosis and present a safe and easy method. Granulomas may appear as a shadow on an x ray. A chest x ray may also show enlarged lymph glands. Granulomas & enlarged lymph glands are both symptoms of sarcoidosis
- Pulmonary Function Tests
- Like x rays, pulmonary function tests are safe and easy to perform. Pulmonary function tests can include:
- using a spirometer - a spirometer is a device which measures the rate and volume a person can blow out after taking a deep breath. Sarcoidosis can scar and/or inflame the tissue of the lungs affecting performance on this test.
- measuring lung volume - sarcoidosis can contract or shrink the lungs, lowering the lungs volume & affecting their capacity to hold air.
- measuring diffusing capacity - the efficiency of gas moving from the lungs into the bloodstream can be affected. Sarcoidosis can make it harder for oxygen to enter the bloodstream.
- Fiber Optic Bronchoscopy
A fiber optic bronchoscope is a slender tubular instrument used to examine the bronchial tubes. A flexible tube passes light through a fibre optic cable. The tube is inserted into the airway of the lung allowing a doctor to inspect the tissue lining.
- Fiber Optic Bronchoscopy Biopsy
A bronchoscope can also be used to take small samples of lung tissue & 'lung washings' (which contain lung cells) from parts of the lungs.
- Bronchoalveolar Lavage (BAL)
A saline solution (salt water) is injected into the lung. The fluid is removed using the suction action from a fibre optic bronchoscope. The fluid is then analyzed for washed out cells and other materials from alveoli (tiny air sacs) of the lung.
The pulmonary inflammation (a symptom of sarcoidosis) begins in the alveoli so washed out cells from this area can indicate sarcoidosis of the lungs.