Because symptoms of sarcoidosis can mimic those of other diseases, in some cases sarcoidosis may be diagnosed by excluding these other similar diseases. Frequently, sarcoidosis is diagnosed because a routine chest x-ray shows an abnormality. To make a diagnosis, most doctors will take a medical history and perform a physical examination. The doctor also may need to perform various tests and procedures to help diagnose sarcoidosis.

Some of the key tests to help monitor the disease during and after treatment include:

Physical Examination:  The doctor will look for symptoms of the disease, such as red bumps on the skin, swollen lymph nodes or redness in the eyes. The doctor also will check for other possible causes of any symptoms.

Chest X-Ray:  A chest x-ray, which poses little risk to health, can detect sarcoidosis. X-ray beams cannot pass as easily through granulomatous or scarred tissue as through normal tissue. The x-ray may show granulomas, which appear as a shadow, or enlarged lymph glands in the chest. Frequently, sarcoidosis is diagnosed because a chest x-ray, taken routinely or for some other reason, shows an abnormality. A staging system is used to classify chest x-rays
taken to detect sarcoidosis.

• Stage 0 is a normal chest x-ray.
• Stage 1 is a chest x-ray with enlarged lymph nodes but otherwise clear lungs.
• Stage 2 is a chest x-ray with enlarged lymph nodes plus
  infiltrates (shadows) in the lungs.
• Stage 3 is a chest x-ray that shows the infiltrates (shadows) are present but the lymph nodes are no longer seen.
• Stage 4 shows scar tissue in the lung tissue.

X-ray stages do not tell the severity of the disease. However, in general the higher the stage of the x-ray, the worse the person’s symptoms and lung function (as measured by breathing tests). But there is a lot of individual variation, and persons at Stages 0 through 3 may or may not have symptoms.

Blood Tests: Blood analyses evaluate the number and types of blood cells in the body. The tests also measure the blood levels of various proteins, such as angiotensin converting enzyme (ACE), which are known to be involved in immunological activities, as well as increases in calcium levels. ACE is made by cells in the granulomas.  However, ACE levels are not always elevated in those with the disease.  Blood tests can also show liver, kidney and bone marrow abnormalities that can occur with sarcoidosis.

Pulmonary Function Tests:  Pulmonary function tests are used to monitor the course of the disease in the lungs. These tests are safe and easy to do, but are frequently expensive. The results are compared over time. One pulmonary function test uses a "spirometer" or a device that measures how much and how fast a person can blow air out of the lungs after taking a deep breath. This amount will be less than normal if there is significant inflammation and/or scarring (or fibrosis) in the lung.  Another test measures lung volume, which indicates how much air the lungs can hold. In some patients, the lungs may shrink or contract due to sarcoidosis, and the lung volumes will be smaller than normal. Other tests check for diffusing capacity, or how well a gas moves into the bloodstream from the lungs. Sarcoidosis makes it harder for oxygen to move from the lungs into the bloodstream. In one test, a device called a pulse oximeter is placed on the finger to give the doctor a rough idea of the level (or saturation) of oxygen in the patient’s blood. An arterial blood gas test is a more accurate way to check the level of oxygen in the bloodstream. Blood from an artery (usually in the wrist) is used because it has passed through the lungs and taken up oxygen. The blood is then analyzed for its oxygen and carbon dioxide levels. The better the lungs are working, the more oxygen there will be in the arterial blood.

Fiberoptic Bronchoscopy:  In this procedure, a long, narrow, flexible tube with a light at the end is inserted into an airway of the lung. This makes it possible for the doctor to look at the tissue lining the air passageways of the lungs. It is also possible to use the bronchoscope to obtain small samples of lung tissue and to obtain lung washings (or lavage) that contain lung cells from various parts of the lungs.

Fiberoptic Bronchoscopy Biopsy: In this procedure, a tiny sample of lung tissue is removed. The procedure is usually done to make the diagnosis when pulmonary function tests or chest x rays are abnormal and characteristic of sarcoidosis. If performed, it is done at the time of a fiberoptic bronchoscopy. The test is done while the patient is awake but slightly sedated. The test is usually very safe and done on an outpatient basis.

Bronchoalveolar Lavage:  Often, a procedure called a bronchoalveolar lavage (BAL) is done as part of a fiberoptic bronchoscopy. BAL involves injecting saline (salt water) into a region of the lung. The fiberoptic bronchoscope then uses suction to remove the fluid, which has washed out cells and other materials from the tiny air sacs (or alveoli) of the lung. The pulmonary inflammation associated with sarcoidosis begins in the lung in these air sacs. The removed sample is examined for signs of inflammation and tested for infections that may mimic sarcoidosis.

CT Scan:  A computed tomographic (CT) scan is a complicated kind of x-ray that gives a better picture of the lungs than the ordinary chest x-ray. A CT scan may be done to better assess how much of the lung is affected by sarcoidosis.  CT scans are not done routinely because they are more costly. Instead, they are done when specific factors call for their need. CT scan of the lungs is important if the patient is coughing up blood.

MR Scan: Magnetic resonance (also called nuclear magnetic resonance, NMR scanning, or magnetic resonance imaging, MRI) uses powerful magnets and radio waves to see inside the body. A computer generates images of the heart, brain and other organs. The test is not invasive and has no known hazards. It can show if features typical of sarcoidosis are present in organs, particularly the brain and spinal cord.

Thallium and Gallium Scans:  These scans are used to help diagnose sarcoidosis and are often done to see if it is in the heart. Thallium and gallium are radioactive elements. The doctor injects one of these into a vein to help determine if the heart has been affected by sarcoidosis or another inflammatory condition. At a specified time after the injection, the body is scanned for radioactivity. Since any inflammation will cause an abnormal uptake of the radioactive element, the test does not give a definitive diagnosis of sarcoidosis.

PET Scans: Positron emission tomography (PET) scanning detects changes in the body’s chemical activities. As with nuclear imaging tests, you are injected with a radioactive tracer, usually a kind of fluoride, before the test. It then travels through the bloodstream, accumulating in areas that show increased chemical activity. Since the parts of an organ that are not functioning properly often show increased chemical activity, PET scanning can help doctors determine whether an organ is healthy or inflamed. It is often used to help diagnose cardiac sarcoidosis or to find a good spot to biopsy.

Heart Tests:  In addition to the imaging techniques described above a number of other tests are sometimes used to help diagnose cardiac sarcoidosis. Electrocardiography and Holter monitoring are probably the simplest and most widely available tools for initial evaluations of your heart rhythm. Heart biopsies are invasive. They are rarely used today to diagnose cardiac sarcoidosis.

Eye Tests: All persons diagnosed with sarcoidosis should have an eye test done by an ophthalmologist (eye doctor), even if there are no symptoms of the disease in the eyes.  If eye symptoms appear, the test will be repeated during treatment. Certain drugs can sometimes cause side effects related to vision. (Refer to the 'Treatment' section of this site for more information on drugs used with sarcoidosis.)  For the eye examination, the doctor looks into the eye for abnormalities.

MONITORING THE DISEASE
Someone who is thought to have sarcoidosis should see their doctor about the disease. Not all patients need to be seen by a doctor who specializes in treating sarcoidosis. Referral to a specialist may be helpful in complicated situations or to help plan treatment. (For more information on doctors who treat sarcoidosis, see the 'Find a Specialist' section of this site.)

Follow-up examinations may include a review of symptoms, physical exams, chest x-rays and blood tests.  How often these tests are performed depends on the specific needs and symptoms of each patient.

The preceding information relating to diagnosing sarcoidosis is drawn in part from the Department of Health and Human Services, the National Institutes of Health and the National Heart Lung and Blood Institute publication on Sarcoidosis.  For more information on NHLBI resources, visit the Links section of this site.