Alpha-1-antiprotease deficiency, alpha-1-antiproteinase inhibitor deficiency, AAT deficiency, alpha-1-antitrypsin (A-1AT) deficiency
This is a blood test to help determine whether liver disorders and lung diseases such as emphysema – particularly if they appear much earlier than they normally would – stem from a genetic disorder called alpha-1antitrypsin deficiency. This disorder is linked to abnormally low levels or absence of alpha-1 antitrypsin (AAT) protein in the blood.
AAT is a protein made in the liver that helps your lungs work normally. The test finds out whether you have normal or damaged copies of a gene that makes this protein. If you have AAT deficiency, you have two damaged copies of this gene, which increases the chance that you will develop debilitating lung or liver problems.
Although it's helpful to know whether you have this genetic disorder, a positive test result may affect your emotional health and your health insurance. For this reason, some groups, including the nonprofit Alpha-1 Foundation, recommend talking with a genetic counselor before getting a medical test that will remain in your health records. Contact a health professional who specializes in advising patients about genetic diseases.
The only way to find out whether you have this genetic disorder is to get tested.
Your doctor may order this test if you have these problems:
Asthma that can't be controlled through aggressive treatment
Shortness of breath during mild exercise
Rapid heartbeat when you stand upVision problems
Bumpy or itchy skin
Chronic obstructive pulmonary disease, or COPD
Emphysema, a serious, progressive lung disease that causes breathing difficulties
Bronchiectasis, a lung problem that causes chronic dilation of the airways
Blood in your vomit
Swelling in your abdomen or legs
Unexplained liver problems, especially if they appear in childhood
Infants who have yellow skin, a sign of jaundice, may also be tested.
Your doctor may also recommend the test if someone in your family has a history of the above conditions.
Your doctor may recommend other tests to rule out other conditions:
Pulmonary function testing. A series of tests to see how well your lungs work.
Chest radiography. X-ray of your lungs.
HRCT (high-resolution CT) and densitometry. More detailed X-rays of your lungs and tests to measure any lung and liver damage.
Liver function tests. A series of blood tests to see how well your liver works.
Abdominal ultrasound. A test that uses sound waves to find evidence of liver damage.
Liver biopsy. A procedure that involves taking a tiny sample of your liver to look for disease.
Your doctor may conduct a series of tests on the serum in your blood to find the damaged genes. These tests include:
Serum AAT concentrations. Tests on a blood sample to look for the AAT protein.
Serum protein electrophoresis with thin-layer isoelectric focusing, which is considered a more accurate test for the gene.
Genetic test. You may consider getting a genetic test before getting a blood test. The genetic test can be done with a blood sample or a swab from inside your mouth.
Many things may affect your lab test results, including the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
A normal result will range between 100 and 200 milligrams per deciliter (mg/dL). If your levels are too low, it may be a sign that you have one damaged gene, which means you are a carrier, or two damaged genes, which means you have AAT deficiency. Talk with your doctor about what your test results mean.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, and feeling dizzy. When the needle pricks your arm, you may feel a slight pain or sting. Afterward, the site may be sore.
Although the physical risks of the test are slight, it may be emotionally upsetting to find out you have a genetic risk for certain diseases. Because it may reveal a chronic health condition, the test may also affect your coverage for health and life insurance. For these reasons, experts recommend seeking genetic counseling.
If the test is done properly, the results should be accurate. But always keep in mind the possibility of a falsely abnormal result.
You don't have to prepare for this test.