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

Blood is drawn from a vein on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child:

The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

Blood is drawn from a vein on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

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

Food and fluids may be restricted for up to 12 hours before the test. People taking steroid therapy should consult their health care providers because steroids can decrease ACE levels.

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.

ACE levels can be used in the evaluation of sarcoidosis and other diseases that are caused or made worse by constricted blood vessels. People with sarcoidosis may have their ACE levels tested regularly to evaluate the severity of the disease and to monitor the response to therapy. This test also helps confirm Gaucher's disease and leprosy.

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

This test is often used to help diagnose sarcoidosis, a condition in which ACE levels are increased 75% of the time. Elevated ACE levels may also be seen in several other disorders, including:

• Active histoplasmosis
• Alcoholic cirrhosis
• Amyloidosis
• Asbestosis
• Berylliosis
• Diabetes
• Gaucher's disease
• Hodgkin's disease
• Hyperthyroidism
• Idiopathic pulmonary fibrosis
• Leprosy
• Myeloma
• Primary biliary cirrhosis
• Pulmonary embolism
• Scleroderma
• Silicosis
• Tuberculosis

• Steroid therapy (usually prednisone)
• Response to therapy for sarcoidosis

The risks associated with having blood drawn are:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

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.

Ferri FF. Ferri’s Clinical Advisor: Instant Diagnosis and Treatment. 2005 ed. St. Louis, Mo: Mosby; 2005:1257.