Sarcoidosis can look like many other diseases, including multiple sclerosis, lymphoma and asthma. Consequently, there is no single way to diagnose Sarcoidosis. Often Sarcoidosis is discovered as part of a routine exam or an effort to evaluate symptoms thought to be caused by another illness. In the course of the diagnosis, your doctor will have to rule out the presence of those other diseases.
Your doctor will ask for a detailed medical history and likely start with a physical exam, including a close examination of any skin lesions. He or she will also listen carefully to your heart and lungs and check your lymph nodes for swelling.
Diagnostic tests can help exclude other illnesses and determine what organs may be affected by Sarcoidosis. Patients may have a chest X-ray to check for lung damage or swollen lymph nodes, a computerized topography (CT) scan, positron emission tomography (PET) scan, blood tests to review overall health, lung function tests that measure breathing and an eye exam to review vision problems.
Here are some more specific tests:
- Blood Tests. These tests can show the number and type of cells in your blood. They also will show whether there are increases in your calcium levels or changes in your liver, kidney, and bone marrow that can occur with Sarcoidosis.
- Lung Function Tests. One test uses a spirometer (spi-rom’e-ter), a device that measures how much and how fast you can blow air out of your lungs after taking a deep breath. If there is a lot of inflammation and/or scarring in your lungs, you will not be able to move normal amounts of air in and out. Another test measures how much air your lungs can hold. Sarcoidosis can cause your lungs to shrink, and they will not be able to hold as much air as healthy lungs.
- Electrocardiogram (EKG). This test will help show if your heart is affected by Sarcoidosis.
- Pulse Oximetry. A small clip attached to your finger tip can show how well your heart and lungs are moving oxygen into your blood.
- Arterial Blood Gas Test. This test is more accurate than pulse oximetry for checking the level of oxygen in your bloodstream. Blood is taken from an artery (usually in your wrist). It is then analyzed for its oxygen and carbon dioxide levels.
- Fiberoptic Bronchoscopy. In this procedure, your doctor inserts a long, narrow, flexible tube with a light on the end through your nose or mouth into your lungs to look at your airways. This tube is called a bronchoscope. You most likely would have this procedure as an outpatient in a hospital under local anesthesia.
- Bronchoalveolar Lavage (BAL). During bronchoscopy, your doctor may inject a small amount of salt water (saline) through the bronchoscope into your lungs. This fluid washes the lungs and helps bring up cells and other material from the air sacs deep in your lungs where the inflammation usually starts to develop. The cells and fluid are then examined for signs of inflammation.
- Biopsy. Your doctor may take a small sample of tissue from one of your affected organs. For example, when breathing tests or chest x rays show signs of Sarcoidosis in your lungs, your doctor may do a fiberoptic bronchoscopy biopsy. This will help confirm the diagnosis. Your doctor inserts a tiny forceps through the bronchoscope to collect tissue that will be examined. Because the granulomas may be spread out in your lungs, the bronchoscope may miss some of them. Biopsies of your skin and liver are sometimes done to detect granulomas in these organs. You may have Sarcoidosis in other organs as well and multiple biopsies may be necessary. However, every organ involved does not need to be biopsied for a diagnosis to be made.
- Computerized Tomography (CT) Scan. This test provides a computer-generated image of your organs that has more detail than a regular chest x ray. It can provide more information about how sarcoidosis has affected an organ.
- Magnetic Resonance (MR) Scan. This test is also called nuclear magnetic resonance (NMR) scanning or magnetic resonance imaging (MRI). This scan uses powerful magnets and radio waves to make images of some of your organs that your doctor doesn’t want to risk doing a biopsy on. For example, an MR scan can be used to diagnose Sarcoidosis in your brain, spinal cord, nerves, or heart.
- Thallium and Gallium Scans. These scans are often done to see if Sarcoidosis is affecting your heart. Thallium and gallium are radioactive elements. Your doctor injects a small amount of one of them into a vein in your arm. The elements collect at places in your body where there is inflammation. After awhile, your body is scanned for radioactivity. Increased radioactivity at any place may be a sign of inflammation. This test gives information on the tissue in your body that has been affected by Sarcoidosis and the amount of damage to it. But since this test shows all inflammation in your body, even inflammation caused by conditions other than Sarcoidosis, it does not give a definite diagnosis of sarcoidosis.
- Positron Emission Tomography (PET) Scan. This test also uses radioactive injections. It may be more sensitive than gallium in detecting areas of inflammation. Some doctors are using it instead of gallium scans.