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Alpha-1 Antitrypsin (A1AT) in Serum

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of Alpha-1 Antitrypsin, a protein produced by the liver that helps protect the lungs from damage caused by enzymes released during inflammation or injury.

Quick summary

["A1AT helps prevent lung diseases and supports immune function; low levels may indicate genetic disorders or lung/lung-related conditions."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
17653-7
Short code
Deprecated S pneumA Ag XXX Ql
Synonyms
Deprecated S pneumA Ag XXX Ql
Category
coagulation
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like chronic cough, shortness of breath, or a history of lung diseases (e.g., emphysema, chronic obstructive pulmonary disease). It may also be checked in people with a family history of A1AT deficiency, liver disease, or unexplained lung issues.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. If you’re on blood thinners, let your provider know before the test.

What the Results Mean

Results help determine if your A1AT levels are low, normal, or high. Low levels may suggest genetic A1AT deficiency, which can increase lung disease risk. High levels may be linked to liver disease or certain medications.

Common Conditions Linked to A1AT Levels

Low A1AT levels are often associated with conditions like **Alpha-1 Antitrypsin Deficiency (AATD)**, which can cause lung diseases (e.g., emphysema) or liver disease. High levels may indicate liver inflammation or cirrhosis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

A1AT plays a protective role in the lungs and blood vessels. Low levels can lead to premature lung damage or liver problems, especially if inherited. Regular monitoring may be needed if you have a family history of AATD or related symptoms.

Short name

Alpha-1 Antitrypsin Level

Frequently asked questions

What causes low Alpha-1 Antitrypsin levels?
Low A1AT levels are most commonly due to a genetic condition called Alpha-1 Antitrypsin Deficiency (AATD). Other rare causes may include liver disease, certain medications, or conditions that damage the liver.
How is Alpha-1 Antitrypsin Deficiency diagnosed?
Diagnosis typically involves blood tests (like this A1AT test) and genetic testing to confirm if you have the genetic mutation linked to AATD. Your healthcare provider may also check for symptoms like chronic cough or lung issues.
Can lifestyle changes help manage A1AT-related conditions?
Yes! If you have AATD, quitting smoking, avoiding lung irritants (like air pollution), and following a healthy diet can help protect your lungs. Some people with severe AATD may also receive enzyme replacement therapy under medical supervision.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy