AAT - Alpha-1 Antitrypsin
Overview & Description
This test measures the amount of the protein alpha-1 antitrypsin (A1AT) in the bloodstream. A1AT is made by the liver and released into the blood. It blocks the action of certain enzymes that are released by dying cells. These enzymes can cause the breakdown of key proteins in the body.
Who is a candidate for the test?
This test is normally performed on people with a family history of emphysema. These individuals often have an inherited deficiency of A1AT. The test may may also done to diagnose swelling, severe infection or tissue or bone death.
How is the test performed?
In order to measure the amount of alpha-1 antitrypsin in the blood, a blood sample needs to be taken. It is usually obtained from a vein on the forearm or hand. The skin over the vein is first cleaned with an antiseptic. Next, a strong rubber tube, or "tourniquet", is wrapped around the upper arm. This enlarges the veins in the lower arm. A thin needle is inserted gently into a vein and the tourniquet is removed. Blood flows from the vein through the needle. It is collected in a syringe or vial and sent to the lab for testing. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding.
Preparation & Expectations
What is involved in preparation for the test?
A person should request specific preparation instructions from his or her healthcare provider.
Results and Values
What do the test results mean?
Normal levels of A1AT in serum range from 93 to 224 mg/dl (milligrams per deciliter) in blood. If special test called serum protein electrophoresis is performed on the drawn blood, levels will range from 0 to 3.1 gm/dl (grams per deciliter).
Increased levels of this protein can occur whenever there is inflammation of some kind in the body or the body is subjected to stress.
Lower levels of A1AT may indicate:
Author:David T. Moran, MD
Editor:Slon, Stephanie, BA
Reviewer:Eileen McLaughlin, RN, BSN
Mosby's Manual of Diagnostic and Laboratory Tests, Kathleen D. Pagana and Timothy J. Pagana