What Is an Alpha-1 Antitrypsin Test

What the Alpha-1 Antitrypsin Test Measures

An alpha-1 antitrypsin test is a blood test that measures how much alpha-1 antitrypsin (AAT) protein is present in your bloodstream. AAT is made by the liver and works to protect the lungs from damage caused by inflammation and enzymes like neutrophil elastase. When levels are too low, the lungs can become vulnerable to conditions such as emphysema, and the liver can be affected by abnormal protein accumulation.

Why the Test Is Ordered

Doctors typically order this test when a person has early-onset COPD, unexplained liver disease, or a family history of AAT deficiency. It helps confirm whether respiratory or liver symptoms stem from insufficient alpha-1 antitrypsin. The test may also be used to monitor people already diagnosed with the deficiency.

How the Test Is Performed

A healthcare professional draws a small blood sample from a vein, usually in the arm. The sample is sent to a laboratory, where the AAT level is measured and compared against a normal reference range. Results are typically available within a few days. No special preparation, such as fasting, is generally required.

Understanding the Results

Normal AAT levels vary by laboratory, but a result below the established threshold may indicate a deficiency. Low levels do not always mean symptoms will develop, as some people with deficient genes never have significant lung or liver problems. High levels can occur during acute inflammation or pregnancy. A doctor interprets the result alongside symptoms, family history, and sometimes genetic testing.

Next Steps After Testing

If the test confirms AAT deficiency, a pulmonologist or specialist may recommend further lung function tests, imaging, and regular monitoring. Avoiding smoking and respiratory irritants becomes especially important. In some cases, augmentation therapy with intravenous AAT may be considered to slow lung damage. Early diagnosis helps guide decisions that protect long-term lung and liver health.