| Definition: |
A test that measures the amount of alpha-1 antitrypsin in the serum.
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| Alternative Names: |
AAT or A1AT
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| How the test is performed: |
Adult or child:
Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and cause veins below the tourniquet to distend (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 tourniquet 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.
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. |
| How to prepare for the test: |
Adults:
There is no special preparation.
Infants and children:
The physical and psychological preparation a parent can provide for this or any test or procedure depends on the child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
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| How the test will feel: |
| When the needle is inserted to draw blood, some people may feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
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| Why the test is performed: |
| 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 proteolytic (digestive) enzymes released by white blood cells may go unchecked and cause widespread damage in the lungs and liver. There is a much higher percentage of people who are heterozygous for the disease (that is, they have one abnormal gene and one normal gene). These people will have lower than normal levels of A1AT, although not as low as homozygous individuals who have 2 copies of the genes and generally more severe disease.
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| What abnormal results mean: |
| Lower-than-normal levels of A1AT may be associated with :
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| What the risks 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
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| Special considerations: |
| 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 others. |
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