Alpha-1 Antitrypsin Testing
Reviewed
Also called: A1AT, AAT, alpha-1-antiprotease deficiency, α1-antitrypsin, serum AAT test, AAT phenotyping test
Alpha-1 antitrypsin (AAT) testing uses a sample of blood or a cheek swab to diagnose a condition called alpha-1 antitrypsin deficiency (AAT deficiency).
Specimen: blood (from arm or finger prick) or cheek swab
Why this test may be ordered
- To diagnose or rule out AAT deficiency in people who have symptoms of lung and/or liver disease that may be caused by AAT deficiency
- To screen people who don't have symptoms but have family members with AAT deficiency
- To guide treatment choices for lung disease that may be caused by AAT deficiency
Preparation and collection
You don't need any special preparations for an AAT test.
For a blood test from your arm, a health care professional will take the blood sample from a vein in your arm, using a small needle. For a finger prick test, a health care professional will prick your fingertip to obtain a small amount of blood. For a cheek swab, a health care professional will wipe the inside of your cheek with a small tool to remove some cells.
There is very little physical risk to a blood test. If the blood was taken from your arm, you may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. There are no risks to having a cheek swab.
Understanding results
If you have questions about your results, talk to your provider.
- Low AAT blood level: If your AAT blood levels are low, it may mean you have AAT deficiency. Limitation: To confirm the diagnosis, you'll need a genotype or phenotype test. Next step: If that testing shows that you have AAT deficiency, your provider may recommend additional testing to evaluate your lung and liver function.
- Two mutated copies of the gene (AAT deficiency): If you have two mutated copies of the gene, it means you have a condition called AAT deficiency. People with this disorder have a higher risk of getting lung disease or liver damage before the age of 45. Limitation: There is no cure for AAT deficiency. But treatments can help prevent your condition from getting worse. Next step: If you have AAT deficiency, the counselor can provide information on the condition, including your risk of passing the disease to your children.
- One mutated copy of the gene (carrier): If you have one mutated copy of the gene, you are a carrier of AAT deficiency. Limitation: In these cases, this means you are at slightly higher risk of developing lung disease, especially if you other risk factors, such as being a smoker. Next step: After testing, a counselor can help you understand your results.
- A low AAT blood level alone is not diagnostic; a genotype or phenotype test is needed to confirm AAT deficiency.
- A normal AAT level does not completely rule out all forms of AAT deficiency, especially if symptoms are present.
- Genetic testing can identify carriers (people with one mutated copy of the gene) who are at slightly higher risk of developing lung disease, especially if they have other risk factors such as smoking.
- There is no cure for AAT deficiency, but treatments can help prevent the condition from getting worse.
What to do next
If you're thinking about having AAT testing or have received abnormal results, it may be helpful to speak with a genetic counselor.
- What do my AAT test results mean for my health?
- Do I need any additional testing to confirm the diagnosis?
- What steps can I take to protect my lungs and liver if I have AAT deficiency?
- Should I consider genetic counseling for myself or my family?
Evidence source
Source: U.S. National Library of Medicine (MedlinePlus). Practices and reference ranges may differ in your country.
U.S. National Library of Medicine: Alpha-1 Antitrypsin Testing