Sarcoidosis is diagnosed based on your signs and symptoms, as well as your medical history, family history, and test results.
Your doctor may perform the following tests to diagnose sarcoidosis:
- Lung function tests: measure how much air you can breathe in and out, how fast you can breathe out, and how well your lungs deliver oxygen to the blood. The most common lung function test is called spirometry and measures how much air you can breathe out after taking a deep breath and how fast you can expel the air.
- Imaging tests: X-ray, computed tomography (CT), positron emission tomography (PET), and magnetic resonance imaging (MRI) scans provide images of structures inside the body. Doctors can visually inspect these images for signs of sarcoidosis. Chest X-rays can show lung damage or enlarged lymph nodes, while PET scans or MRI scans can show sarcoidosis that affects the heart or nervous system.
- Biopsies: your doctor may wish to examine a small amount of your tissue in a laboratory to look for granulomas. This is called a biopsy. It is easiest to take a biopsy of the skin, but tissue from the lungs can be biopsied using an instrument called a bronchoscope, which is inserted into the lungs through the nose or mouth. The lungs and lymph nodes can also be biopsied surgically.