Angiotensin-Converting Enzyme (ACE, Kinase II)

ACE production occurs mainly in the epithelial cells of the pulmonary bed. Smaller amounts are found in blood vessels and renal tissue, where ACE converts angiotensin I to angiotensin II; this conversion helps regulate arterial blood pressure. Angiotensin II stimulates the adrenal cortex to produce aldosterone. Aldosterone helps the kidneys maintains water balance by retaining sodium and promoting the excretion of potassium.

Normal range: 8 " “53 U/L.

Use

Evaluation of patients with suspected sarcoidosis

Evaluate the severity and activity of sarcoidosis

Evaluation of hypertension

Evaluation of Gaucher disease

Interpretation

Increased In

Active pulmonary sarcoidosis (50 " “75% of patients but only 11% with inactive disease)

Gaucher disease (100%)

DM (>24%)

Hyperthyroidism (81%)

Leprosy (53%)

Chronic renal disease

Cirrhosis (25%)

Silicosis (>20%)

Berylliosis (75%)

Amyloidosis

TB infection

Connective tissue diseases

Fungal disease, histoplasmosis

Decreased In

Far-advanced lung neoplasms

Anorexia nervosa associated with hypothyroidism

COPD, emphysema, lung cancer, cystic fibrosis

Starvation

Limitations

False-positive rate equals 2 " “4%.

Levels may be normal in lymphoma and lung cancer.

Serum ACE is significantly reduced in patients on ACE inhibitors (e.g., enalapril and captopril).

The reference interval for children and adolescents may be as much as 50% higher than specimens from adults.

Serum ACE abnormality has been reported in 20 " “30% ofα1-antitrypsin variants (MZ, ZZ, and MS Pi types) but in only about 1% of individuals with normal MM Pi type. There is evidence that paraquat poisoning (because of its effect on pulmonary capillary endothelium) is associated with elevated serum ACE.