ACE

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Also known as: serum angiotensin converting enzyme; SACE
Formal name: Angiotensin converting enzyme

At a Glance

Why Get Tested?

To help diagnose and monitor sarcoidosis; to help differentiate this systemic condition from other disorders causing similar symptoms

When to Get Tested?

When you have granulomas that create small bumps under the skin, a lingering cough, red watery eyes, and/or other symptoms suggestive of sarcoidosis; regularly when you have active sarcoidosis to monitor its course

Sample Required?

A blood sample drawn from a vein in your arm

The Test Sample

What is being tested?

Angiotensin converting enzyme (ACE) is an enzyme produced by vascular endothelial cells to help regulate blood pressure. It catalyses the conversion of angiotensin I (an inactive protein) to angiotensin II. Angiotensin II functions as a strong vasopressor - it causes arteries to contract, making them temporarily narrower and increasing the pressure of the blood flowing through them. ACE is produced throughout the body, but is especially concentrated in the lungs. It is normally found in high levels in the blood in those less than 20 years of age, but then drops to a relatively stable lower level in healthy adults.

Increased amounts of ACE are sometimes secreted by cells found at the margins (outside borders) of granulomas. Granulomas are small tumour-like masses of immune and inflammatory cells and fibrous tissue that create bumps under the skin and throughout the body. They are a classic feature of sarcoidosis, a systemic disorder of unknown cause that often affects the lungs but may also affect many other body organs including the eyes, skin, nerves, liver and heart. ACE levels often increase when granulomas develop. About 50-80% of patients with active sarcoidosis will have elevated levels of ACE – levels that will rise and fall with disease activity.

Granulomas, fibrosis and elevated ACE levels may also be seen with infectious disorders, such as leprosy and tuberculosis (the granulomas form around the invading mycobacteria) and with exposure to irritant particle poisons such as beryllium, asbestos, and silicon (with current worker protection, these causes are relatively rare).

How is the sample collected for testing?

A blood sample is obtained by inserting a needle into a vein in the arm.

The Test

Common Questions

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.