Angiotensin Converting Enzyme (ACE) Test

The angiotensin-converting enzyme (ACE) test is a blood test that checks the level of angiotensin-converting enzyme in the blood. The test is also called the serum angiotensin converting enzyme (SACE) test.

ACE is an enzyme that helps control blood pressure and maintain the right balance of minerals and fluids (electrolytes) in the body. ACE is produced by cells in the body, mainly those lining the blood vessels in the lungs. The test is important for diagnosing and monitoring sarcoidosis (a condition where the lymph nodes, eyes, liver, and skin become inflamed) and Gaucher disease (a genetic condition in which the body lacks the enzyme glucocerebrosidase). Therefore, this test is important for doctors to help diagnose these serious conditions and begin proper treatment quickly.

You will be advised to take the ACE test if you have any of the following symptoms indicating abnormal levels of ACE protein:

• Shortness of breath
• Chest pain
• Dry cough
• Weight loss
• Fatigue
• Fever
• Vision changes
• Dry eyes

The test is also advised for the following categories of people:

• Individuals with kidney disease – ACE is an important part of the renin angiotensin system (RAS), which controls blood pressure and fluid balance in the body. Changes in this system can make renal (kidney disease) worse.
• Individuals with high blood pressure – ACE plays an important role in regulating and maintaining normal blood pressure.

The ACE blood test can be used to help diagnose or confirm the diagnosis of certain conditions, such as:

• Sarcoidosis – This is a condition in which the lymph nodes, eyes, liver, and skin become inflamed. Small clumps of abnormal tissue begin to grow in certain areas of the body.
• Gaucher disease – This is a genetic condition in which a person does not have an enzyme called glucocerebrosidase enzyme (GBA).

What to Expect Before the Angiotensin Converting Enzyme (ACE) Test

No fasting is required for a standalone Angiotensin Converting Enzyme (ACE) test. You can eat and drink normally. However, if it is part of a broader package that includes fasting tests, your doctor may advise fasting for 8-12 hours. Avoid strenuous exercise for 24 hours before the test, as intense physical activity can temporarily raise angiotensin converting enzyme (ACE) levels and affect interpretation. Always inform your doctor about any ongoing medications.

What to Expect During the Blood Collection

A phlebotomist cleans the skin with an antiseptic, then places an elastic band around your upper arm to make the veins easier to access. A small needle is inserted into the vein; you may feel a brief pinch. Blood is collected into a labelled tube in under a minute.

What to Expect After the Angiotensin Converting Enzyme (ACE) Test

A small cotton swab and bandage are placed over the site to stop any minor bleeding. You can return to normal activities immediately. Minor bruising is normal and disappears quickly. If dizzy, sit and rest for a few minutes.

In the ACE test, the primary parameter being measured is:

• The amount of angiotensin-converting enzyme in a sample of blood.

The ACE normal range is indicated in the table below.

Note: The normal range may vary slightly depending on the laboratory and individual health conditions.

The table below provides a general interpretation of the ACE test results based on whether the levels are low or high.

Note:

• Steroids can decrease ACE levels and affect test results. Tell your doctor about any medicines you are taking.
• The ACE test must be interpreted along with clinical symptoms, medical conditions, and other blood test results.

Like any other medical test, this test also has certain risks and limitations.

Risks:

• The ACE test is generally safe and involves minimal risk. You may feel slight pain when the needle is inserted or mild bruising afterwards, which usually resolves spontaneously.

Limitations:

• A high ACE level alone cannot confirm a diagnosis and must be interpreted along with other medical tests.
• ACE levels can be influenced by certain hormones, such as thyroid and steroid hormones.

Depending on your symptoms and results, your doctor might recommend additional tests to better understand your condition:

• Chest X-ray
• CT scan of the chest
• Brain and liver imaging tests
• Echocardiogram or magnetic resonance imaging (MRI) of the heart
• Calcium test
• Complete blood count (CBC)
• Immunoelectrophoresis (to detect and identify different proteins in your blood and urine)
• Bone marrow aspiration
• Genetic testing