The Angiotensin Converting Enzyme (ACE) test is a blood test that measures the levels of the ACE enzyme in the blood. ACE is an enzyme that plays a role in regulating blood pressure by converting angiotensin I into angiotensin II, a potent vasoconstrictor that narrows blood vessels and raises blood pressure. The ACE test is commonly used to diagnose and monitor conditions that affect the lungs, such as sarcoidosis, a disease that causes inflammation and small lumps of cells to form in various organs, including the lungs. Elevated levels of ACE in the blood can indicate inflammation and tissue damage, while low levels may be a sign of improvement or response to treatment. The ACE test involves taking a small sample of blood, which is then analyzed in a laboratory to determine the levels of the enzyme. Depending on the results of the test, doctors may recommend additional diagnostic tests or treatments to address underlying conditions. Regular monitoring of ACE levels can also be used to track the progression of lung disease and evaluate the effectiveness of treatment.