Sarcoidosis > Diagnosis

Sarcoidosis: Diagnosis

The first step in diagnosing sarcoidosis is a good evaluation. The inflamed microscopic granulomas seen in the affected organ with sarcoidosis are similar to those in other diseases such as tuberculosis, fungal diseases, berylliosis, and farmer's lung. Because of this, a careful evaluation is necessary to make a diagnosis. Only after the known causes of granulomas have been ruled out is the diagnosis of sarcoidosis made.

An evaluation to detect sarcoidosis should include the following:

  • Thorough Medical Examination: This can help rule out other diseases that may be similar to sarcoidosis.

  • Chest X-Ray: Doctors look at chest X-rays for evidence of enlarged lymph nodes and small round spots in the lung caused by the clusters of inflammation. "Staging" can help the doctor determine the degree of lung involvement in sarcoidosis. A scale of 0-4 is commonly used, with 4 having the highest amount of lung involvement.

  • Pulmonary Function Tests: These standard breathing tests give an indication of the severity of lung disease. There is nothing unique about sarcoidosis on these tests, so they do not substitute for other, more specific tests. Pulmonary function tests can show obstruction of airflow out of the lungs, restriction of the lung's ability to take in air, and a decrease in the transport of oxygen from the lung into the blood stream. The most important types of breathing tests in sarcoidosis are spirometry, lung volumes, and diffusing capacity. In some cases, measurement of blood oxygen levels during an exercise test should also be done.

  • Tissue Biopsy: A microscopic examination of tissue samples from the lungs or other affected organs is also needed to be absolutely sure of the diagnosis. A bronchoscopy can obtain this tissue. A bronchoscopy is an outpatient procedure in which the doctor places a narrow tube through the nose and into the airways. Sometimes the diagnosis is made by obtaining tissue samples from the skin, liver, or enlarged lymph nodes.

  • Bronchoalveolar Lavage: When a bronchoscopy is done, a small part of lung can be washed (lavaged) in order to obtain some cells of the immune system from the lung. By counting the types of cells in lavage fluid, it is possible to get an estimate of how inflamed the lungs are and whether the type of inflammation is characteristic of sarcoidosis.

  • Eye Examination: A slit lamp examination by an eye doctor (ophthalmologist) is an important part of an eye examination to detect inflammation.

  • Serum Angiotensin Converting Enzyme Level (S.A.C.E.): This blood test is also useful. If the level of this blood test is high, it can indicate the presence of sarcoidosis. It can sometimes be used to monitor if sarcoidosis is improving or worsening. Unfortunately, other diseases can cause increased S.A.C.E. blood levels also, so this test cannot be used alone to make the diagnosis.

  • CT Scan: A CT scan is a detailed type of X-ray. The CT scan may make it possible to see lymph nodes and scars in the lung when regular chest X-rays sometimes cannot.

  • Gallium Scan. This is another type of X-ray scan. A small amount of radioactive material is injected into a person's blood, which travels to areas of the body that are inflamed. An X-ray camera scans the body to see where the radioactive material has collected. Although not needed in all cases, gallium scanning can help show sarcoidosis in many organs, including the lungs, salivary glands, bone, spleen, and liver. It is not frequently used these days.

  • Calcium Levels in the Blood and Urine: People with sarcoidosis can have sensitivity to vitamin D. This results in too much calcium being absorbed through the intestines. This can cause a high level of calcium in the blood and/or urine. Exposure to the sun can further stimulate this process. It may be necessary to collect a urine sample for 24 hours to measure the calcium level as well as collect a blood sample for calcium. There are rarely symptoms seen with high levels of calcium in the blood. If symptoms are present they may include vague bone pain and frequent urination.

  • Kveim Test: The Kveim test is a test in which an extract of sarcoid-affected tissue is injected under the skin. It is not used very often in a sarcoidosis evaluation these days.

  • PET (Positron Emission Tomography) Scan: This is a special kind of scan where a patient is given radioactive labeled sugar intravenously and then the patient is placed in a special scanning machine to see where the radioactive labeled sugar accumulated. Areas of active inflammation take up the radioactive labeled sugar and this can be detected with the scanning machine giving your doctor a better idea of which areas or organs might be involved with sarcoidosis.

  • Heart Testing: The doctor might order an electrocardiogram to evaluate the electrical system of the heart and an echocardiogram to evaluate the structure and function of the heart. Occasionally, the doctor might order further tests for the heart if there is suspicion of possible heart involvement with sarcoidosis. These tests might include a holter monitor and/or a heart MRI (Magnetic Resonance Imaging).