In most cases, your doctor will diagnose sarcoidosis based on three factors:
You have symptoms and physical findings that suggest sarcoidosis.
Your chest X-ray shows abnormal areas that are consistent with sarcoidosis.
You have had a biopsy done, and it shows signs of sarcoidosis. A biopsy is a small piece of tissue that is removed for laboratory testing. This tissue sample can be taken from your lung, skin, lip or another inflamed or abnormal area of the body.
It is common for sarcoidosis to be suspected based on abnormal results on a chest X-ray ordered for unrelated reasons. For example, a person who is otherwise healthy may have a chest X-ray as a requirement for his or her work and discover abnormalities that suggest the diagnosis.
Besides the chest X-ray and biopsy mentioned above, additional tests may be needed. These tests may be done to rule out other illnesses or to assess the amount of organ damage caused by sarcoidosis. Some of the most common tests are:
Blood tests to measure levels of calcium or angiotensin-converting enzyme, which may be high in people with sarcoidosis
Blood tests to evaluate how well your liver is functioning
Lung function tests to measure how well you breathe
A complete eye examination