ACE levels

Definition

ACE levels is a blood test that measures the amount of angiotensin-converting enzyme (ACE).

Alternative Names

Serum angiotensin-converting enzyme; SACE

How the test is performed

Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.

Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.

After the blood has been drawn, it goes to a laboratory to be evaluated.

How to prepare for the test

You may have to restrict food and fluids for up to 12 hours before the test. People taking steroid therapy should talk to their health care providers, because steroids can decrease ACE levels.

How the test will feel

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed

ACE levels can be used in the evaluation of sarcoidosis and some other diseases. People with sarcoidosis may have their ACE levels tested regularly to check the severity of the disease and to monitor the response to therapy. This test also helps confirm Gaucher's disease and leprosy.

Normal Values

Normal values vary based on your age and the test method used. Typically, adults have ACE levels less than 40 micrograms/L.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

What abnormal results mean

Increased ACE levels may be a sign of sarcoidosis. However, increased ACE levels may also be seen in several other disorders, including:

• Active histoplasmosis
• Amyloidosis
• Asbestosis
• Berylliosis
• Diabetes
• Emphysema
• Gaucher's disease
• Hepatitis
• Hodgkin's disease
• Hyperthyroidism
• Idiopathic pulmonary fibrosis
• Leprosy
• Lung cancer
• Nephrotic syndrome
• Primary biliary cirrhosis
• Pulmonary embolism
• Scleroderma
• Silicosis
• Tuberculosis

A decrease in ACE levels may indicate:

• Steroid therapy (usually prednisone)
• Therapy for sarcoidosis

What the risks are

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

The risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Special considerations

Because elevated ACE levels may also be seen in several other disorders, the overall usefulness of the ACE blood test is limited.

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References

Abraham NZ, Carty RP, DuFour DR, Pincus MR. Clinical enzymology. In: McPherson RA, Pincus MR, eds. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 21st ed. Philadelphia, PA: Saunders Elsevier; 2006:chap 20.

Weinberger SE. Sarcoidosis. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, PA: Saunders Elsevier; 2007:chap 95.