Test/Range/Collection

Angiotensin-converting enzyme, serum (ACE)

8-65 U/L

(age-dependent)

Gold SST, red

$$

Separate serum from cells as soon as possible or within 2 hrs after collection.

Physiologic Basis

ACE is part of the renin-angiotensin cascade. It is a dipeptidyl carboxypeptidase that converts angiotensin I to the vasopressor, angiotensin II.

ACE is normally present in the kidneys and other peripheral tissues. Serum levels in healthy subjects are dependent on polymorphisms in ACE genes. In granulomatous disease, ACE levels increase, derived from epithelioid cells within granulomas.

There is a high level of inter-individual variability in serum ACE due to genetic polymorphism.

Interpretation

Increased in: Sarcoidosis (~60%), hyperthyroidism, acute hepatitis, primary biliary cirrhosis, diabetes mellitus, multiple myeloma, osteoarthritis, amyloidosis, Gaucher disease, pneumoconiosis, histoplasmosis, miliary tuberculosis. Drugs: dexamethasone.

Decreased in: Renal disease, obstructive pulmonary disease, hypothyroidism.

Comments

Serum ACE is elevated in most (~60%) patients with active sarcoidosis. Test is not useful as a screening test for sarcoidosis since the sensitivity is low. Specificity is compromised by positive tests in diseases more common than sarcoidosis. Result needs to be correlated with diagnostic imaging and tissue biopsy findings.

Some advocate measurement of ACE to follow disease activity in sarcoidosis; there is a significant decrease in ACE activity in some patients receiving prednisone.

Genotyping may increase the utility of ACE in sarcoidosis due to the large interindividual biological variation in ACE levels.

Fl⊘e A et al. Genotyping increases the yield of angiotensin-converting enzyme in sarcoidosis—a systematic review. Dan Med J 2014;61:A4815.  [PMID: 24814734]

Heinie R et al. Diagnostic criteria for sarcoidosis. Autoimmun Rev 2014;13:383.  [PMID: 24424172]

Keir G et al. Assessing pulmonary disease and response to therapy: which test? Semin Respir Crit Care Med 2010;31:409.  [PMID: 20665391]