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Alpha-1 Antitrypsin Level, Serum/Plasma

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

This blood test measures alpha-1 antitrypsin, a liver-made protein that helps protect the lungs from inflammation.

Quick summary

["The result can help evaluate inherited alpha-1 antitrypsin deficiency and may also be affected by liver disease or inflammation."]

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

Key facts at a glance

LOINC
12960-1
Short code
A1AT Cl SerPl+Stl-aCnc
Synonyms
A1AT Cl SerPl+Stl-aCnc
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?

This test measures the amount of alpha-1 antitrypsin (A1AT) in blood. A1AT is a protein made by the liver that protects lung tissue from damage caused by inflammation.

Why might I need this test?

The test may be ordered if you have unexplained lung disease, chronic bronchitis, or worsening COPD. It is also used when liver disease or an abnormal protein level suggests possible alpha-1 antitrypsin deficiency.

How is the test performed?

A blood sample is collected, and the A1AT level is measured using a laboratory method. If the level is abnormal, your clinician may recommend repeat testing or additional tests to clarify the cause.

How do I prepare for the test?

No special preparation is usually required. Tell your clinician about any liver disease, infection, pregnancy, or medicines you are taking, because these factors can affect the A1AT level.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Alpha-1 antitrypsin (A1AT)

Frequently asked questions

What does alpha-1 antitrypsin do?
Alpha-1 antitrypsin is a protective protein that limits inflammation, especially in the lungs. It is produced mainly by the liver.
What can cause a low alpha-1 antitrypsin level?
The most common cause is an inherited genetic condition called alpha-1 antitrypsin deficiency. Certain liver diseases can also be associated with lower levels.
Does inflammation affect this test?
Yes. A1AT is an acute-phase reactant, so infection, other inflammation, pregnancy, and some liver conditions may raise its level. Your clinician will interpret the result in context.
  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