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How is sarcoidosis diagnosed?

The diagnosis of sarcoidosis is based on the patient's medical history, physical examination, laboratory tests, lung function studies, and chest x-ray. The physical examination in sarcoidosis may reveal the characteristic skin lesions. Wheezes may be heard throughout the lungs. The liver may be enlarged. Examination of the eyes using a special light called a slit-lamp may reveal changes indicative of sarcoidosis. Lung function tests measures such things as the amount of air an individual

can breathe in and breathe out, the speed at which the air flows in and out, and the amount of air left in the lung after blowing out as much as possible in one second. A variety of lung function tests may show abnormal results in sarcoidosis.

Doctors most often diagnose sarcoidosis by observing its distinctive changes, including enlarged lymph nodes and a hazy, ground-glass appearance of lung tissue on a chest x-ray or on computed tomography (CT). When further testing is necessary, microscopic examination of a tissue specimen showing inflammation and granulomas confirms the diagnosis. Bronchoscopy with transbronchial lung biopsy is the best procedure for most people. Other possible sources of tissue specimens are skin abnormalities, enlarged lymph nodes close to the skin, and granulomas on the conjunctiva. Examination of a specimen from one of these tissues is accurate in 87% of cases. A liver biopsy is rarely needed even if there is evidence that the liver is affected.

Other methods that can help a doctor diagnose sarcoidosis or assess its severity include measuring the level of angiotensin-converting enzyme (ACE) in the blood, irrigating the lungs and examining the fluid, and using a whole-body gallium scan. In many people with sarcoidosis, the level of angiotensin-converting enzyme in the blood is high. The washings from a lung with active sarcoidosis contain a large number of lymphocytes, but this is not unique to sarcoidosis. Because gallium scanning shows abnormal patterns in the lungs or lymph nodes of a person with sarcoidosis in those places, this test is sometimes used when the diagnosis is uncertain.

Bronchoscopy is a very helpful diagnostic test. This involves passing a tiny tube (bronchoscope) through the nose or mouth, down the trachea, and into the airways (bronchial tubes). The bronchial tubes can be inspected through the bronchoscope. The bronchoscope is also designed in such a way as to allow biopsies to be obtained. Bronchoalveolar lavage involves washing the surfaces with a sterile saltwater (saline) solution. The saline is then retrieved and examined in a laboratory. Cells and debris from within the bronchial tubes and the tiny sacs of the lung (the alveoli) will be obtained in this way, and can be studied for the presence of an abnormally large number of white blood cells. A tiny piece of the lung tissue can also be obtained through the bronchosocope. This can be studied under a microscope to look for the characteristic granulomas and inflammation of sarcoidosis.

In people with lung scarring, pulmonary function tests may show that the amount of air the lung can hold is below normal. Blood tests may reveal a low number of white blood cells or platelets. Immunoglobulin levels are often high, especially in blacks. The levels of liver enzymes, particularly alkaline phosphatase, may be high if the liver is affected.


More information on sarcoidosis

What is sarcoidosis? - Sarcoidosis is a multisystem granulomatous disorder of unknown etiology, characterized histologically by noncaseating epithelioid granulomas involving various organs.
What causes sarcoidosis? - The exact cause of sarcoidosis is not known. Sarcoidosis is currently thought to be associated with an abnormal immune response.
Who is at risk of sarcoidosis? - Sarcoidosis is more commonly seen in blacks than whites, primarily people of northern European decent in the latter case.
What are the symptoms of sarcoidosis? - Symptoms of sarcoidosis include dry cough, shortness of breath, skin lesions, renal, liver and heart involvement, neuropathy.
How is sarcoidosis diagnosed? - The diagnosis of sarcoidosis is based on the patient's medical history, physical examination, laboratory tests, lung function studies, and chest x-ray.
What is the treatment for sarcoidosis? - The most effective treatment for sarcoidosis is the administration of steroid medications. Sarcoidosis responds very well to steroids.
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