Angiotensin-Converting Enzyme (ACE) is used to detect and monitor the clinical course of sarcoidosis (a granulomatous disease that affects many organs, especially the lungs). Furthermore, it is used to differentiate between sarcoidosis and other granulomatous diseases. It is also used to differentiate active and dormant sarcoid disease.
Angiotensin-Converting Enzyme is found in pulmonary epithelial cells and converts angiotensin I to angiotensin II (a potent vasoconstrictor). Angiotensin II is a significant stimulator of aldosterone. ACE is vital in the renin/aldosterone mechanism and therefore important in controlling blood pressure. Despite this, ACE is not very helpful in the evaluation of hypertension. Its value is in the detection of sarcoidosis.
High Angiotensin-Converting Enzyme levels are found in a high percentage of patients with sarcoidosis. This test is primarily used in patients with sarcoidosis to evaluate the severity of disease and the response to therapy. Levels are especially high with active pulmonary sarcoidosis and can be normal with inactive (dormant) sarcoidosis. Elevated ACE levels also occur in conditions other than sarcoidosis, including Gaucher disease (a rare familial lysosomal disorder of fat metabolism), leprosy, alcoholic cirrhosis, active histoplasmosis, tuberculosis, Hodgkin disease, myeloma, scleroderma, pulmonary embolism, and idiopathic pulmonary fibrosis. An ACE assay can be performed using spectrophotometry or radio-immunoassay.
Causes of Angiotensin-Converting Enzyme False Indications
- Patients under 20 years of age normally have very high Angiotensin-Converting Enzyme levels.
- Hemolysis or hyperlipidemia may factitiously decrease Angiotensin-Converting Enzyme levels.
- Drugs that may cause decreased Angiotensin-Converting Enzyme levels include ACE inhibitor antihypertensives and steroids.
Causes of High Angiotensin-Converting Enzyme Levels
Sarcoidosis: This is the disease for which this test is primarily performed. The more severe the sarcoidosis, the greater the likelihood that ACE will be increased.
Other rare diseases that have been found to be associated with ACE elevations include Gaucher Disease, Tuberculosis, Leprosy, Alcoholic Cirrhosis, Active Histoplasmosis, Hodgkin Disease, Myeloma, Idiopathic Pulmonary Fibrosis, Diabetes Mellitus, Primary Biliary Cirrhosis, Amyloidosis, Hyperthyroidism, Scleroderma, and Pulmonary.