ACE: Angiotensin Converting Enzyme

Sample: Fresh serum. Separate 1 mL of serum as soon as possible after collection and store refrigerated at 4°C.

Schedule: Daily

Units: Units ACE

Range: Up 53 Units ACE

Remarks: The principal site for production of ACE is the pulmonary bed of endothelial cells. It is known for its generation of Anigotensin II. The principal use of ACE is in sarcoidosis diagnosis, mainly when the disease is active as well as in assessing the response to corticosteroid therapy.

Serum ACE activity is increased in more than half of sarcoidosis patients. Low ACE levels correlates well with favorable prognosis whereas raising levels may reflect activity uncontrolled by the therapy. ACE test has low sensitivity as a diagnostic tool for sarcoidosis. On the other hand, ACE levels are less likely to rise in chronic sarcoidosis.

High levels of ACE are seen also in Gauchers disease. The biologically inactive Angiotensinogen is converted to the inactive also Angiotyensin I by the enzyme Renin. Renin is a proteolytic enzyme that is produced by the juxtaglomerular cells of the kidney. In the circulation, renin acts to cleave renin substrate to produce the decapeptide, Angiotensin I.

The inactive Angiotensin I then is cleaved by Angiotensin Converting Enzyme (ACE) to form the biologically active octopeptide, Angiotensin II. Angiotensin II is an extremely potent vasopressor that plays an important role in blood pressure regulation. Angiotensin II also stimulates the production of Aldosterone by the Adrenal gland.


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