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 isn't 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. In people with pulmonary scarring, pulmonary function tests show that the amount of air the lung can hold is below normal. Blood tests may reveal a low number of white blood cells.
Immunoglobulin levels are often high, especially in blacks.
The levels of liver enzymes, particularly alkaline phosphatase, may be high if the liver has been affected. Commonly, sarcoidosis improves or clears up spontaneously. More than two thirds of people with lung sarcoidosis have no symptoms after 9 years. Even enlarged lymph nodes in the chest and extensive lung inflammation may disappear in a few months or years. More than three quarters of those with only enlarged lymph nodes and more than half of those with lung involvement recover after 5 years.