Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band or blood pressure cuff is placed around the upper arm to cause veins to swell 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 infants or young children:
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.

• infant test or procedure preparation (birth to 1 year)
• toddler test or procedure preparation (1 to 3 years)
• preschooler test or procedure preparation (3 to 6 years)
• schoolage test or procedure preparation (6 to 12 years)
• adolescent test or procedure preparation (12 to 18 years)

This test is helpful in identifying a rare form of emphysema in adults and a rare form of cirrhosis in children. In the absence of A1AT, certain digestive enzymes released by white blood cells may go unchecked and cause widespread damage in the lungs and liver.

Everyone has two copies of the gene that makes A1AT. Most people with the disease have one normal gene for A1AT, and only one abnormal gene. These people will have lower than normal levels of A1AT, but not as low as people who have 2 abnormal copies and generally more severe disease.