Alpha-1 Antitrypsin, Serum/Plasma — Substance Concentration
This blood test measures alpha-1 antitrypsin, a protein that protects the lungs and liver. It is mainly used to evaluate possible alpha-1 antitrypsin deficiency.
["The result can help identify alpha-1 antitrypsin deficiency, a condition that may increase the risk of lung and liver disease."]
Key facts at a glance
- LOINC
- 76481-1
- Short code
- A1AT SerPl-sCnc
- Synonyms
- A1AT SerPl-sCnc
- Category
- liver
- 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
What is this test?
Alpha-1 antitrypsin is a protein made by the liver that helps prevent damage to lung tissue. This test measures its concentration in blood collected as serum or plasma.
Why might I need this test?
Your clinician may order this test if you have unexplained chronic lung disease, liver abnormalities, or a family history of alpha-1 antitrypsin deficiency. It may also be used to monitor a person with a previously identified low level.
How is the test performed?
A blood sample is drawn from a vein and tested in a laboratory to determine the concentration of alpha-1 antitrypsin. Additional genetic testing may be recommended if the result suggests deficiency.
How do I prepare for the test?
Fasting is usually not required, but follow your clinician's instructions. Tell the laboratory if you are pregnant or recently ill, because inflammation, infection, pregnancy, and some medicines can temporarily affect the result.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
A low concentration may indicate alpha-1 antitrypsin deficiency, which can increase the risk of emphysema, other chronic lung conditions, and liver disease. A high concentration may occur during inflammation, infection, pregnancy, or with certain medicines, so results should be interpreted alongside the clinical situation. If the level is unexpectedly abnormal, your clinician may repeat the test or recommend phenotyping and genetic testing.
Short name
Alpha-1 antitrypsin
Frequently asked questions
Is alpha-1 antitrypsin the same as an A1AT test?
Does a low alpha-1 antitrypsin level mean I will definitely have lung or liver disease?
Can illness or medicines change the result?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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