Diagnosing sarcoidosis can be challenging because symptoms vary greatly. Early symptoms are shared with a number of conditions, and a diagnostic test that can specifically distinguish sarcoidosis from others does not exist yet. For these reasons, several tests are needed to help the physicians exclude other conditions and reach an accurate diagnosis.
Physical examination and medical history
During physical examinations, physicians listens to the lungs of patients, examines their lymph nodes for swelling, and checks for any skin lesions. They may also inquire about complaints such as fever, cough, weight loss, and shortness of breath.
Sharing the patient’s detailed medical history with the physician regarding infections and certain environmental factors plays an important role in the diagnostic process.
In the event that the physical exam and medical history of the patient raises suspicions of sarcoidosis, a differential diagnosis is necessary to help rule out other possibilities. If the physician concludes that the differential diagnosis points to the possibility of sarcoidosis, further testing is needed for confirmation.
Lungs are the most commonly affected organs in people with sarcoidosis. A chest X-ray is used to detect granulomas in the lungs and lymph nodes. For a more detailed visualization, the physician might prefer a computerized tomography (CT) scan of the chest.
Based on how much inflammation is found in the lymph nodes and lungs, the patient is classified as having stage 1, 2, 3, or 4 sarcoidosis.
The condition can also affect the heart and the central nervous system. An electrocardiogram (EKG) or echocardiogram (echo) can be used to assess heart function. Magnetic resonance imaging (MRI) and positron emission tomography (PET) are used to assess whether there is any central nervous system involvement.
A Gallium scan, where a radioactive material is injected into the vein, may provide additional information about the inflammation sites in the body.
If there are bumps and rashes on the skin, a small sample can be taken for pathological analysis of the granulomas. This is called a skin lesion biopsy, which is a very safe procedure that requires numbing only the tissue from where the sample will be taken.
It may also be necessary to take a sample from the lungs. This test is more likely to give a definitive diagnostic result. It is a safe procedure called a bronchoscopy and can be performed without general anesthesia. A bronchoscopy can also help the physician to exclude infections as the source of symptoms.
In rare cases when other tests are inconclusive, the physician might ask for a sample of the lymph nodes found in the chest. This requires a minor surgical procedure called a mediastinoscopy performed under general anesthesia.
Liver, kidney, bone marrow, and glands that make tears and saliva, muscles, and lymph nodes in other parts of the body can also be tested if necessary.
Blood tests measure numbers of immune cells to assess the level of inflammation in the body.
Blood and urine samples can also be tested for increased levels of some components such as angiotensin-converting enzymes, which is excessively produced by granulomas; alkaline phosphatase, which signals abnormal liver activity; and calcium and creatinine, which indicate poor kidney function.
Granulomas in the lungs may cause decreased lung volume, resulting in reduced lung function. A lung function test is commonly performed to see how well the lungs can expand and supply oxygen to the body.
Eyes are commonly damaged because of sarcoidosis, even though there are no symptoms. A thorough examination of the eyes can reveal whether there is any inflammation, small granulomas inside the eyelids or on the white of the eye, or nerve damage.
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