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Alpha-1 Antitrypsin, Serum/Plasma

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

A blood test that measures alpha-1 antitrypsin, a liver-made protein that helps protect lung tissue from inflammation.

Quick summary

["This test can help evaluate alpha-1 antitrypsin deficiency, which may increase the risk of lung and liver disease."]

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

Key facts at a glance

LOINC
110771-3
Short code
A1AT Msmt SerPl
Synonyms
A1AT Msmt SerPl
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 mainly by the liver. It travels in the blood and helps protect the lungs from damage caused by inflammation.

Why might I need this test?

This test may be ordered when alpha-1 antitrypsin deficiency is suspected, especially with unexplained chronic lung disease, liver disease, or a family history of these conditions.

How is the test performed?

A blood sample is collected and separated into serum or plasma. A laboratory then measures the amount of alpha-1 antitrypsin in the sample.

How do I prepare for the test?

Fasting is usually not required for this test. Follow any instructions from your healthcare professional or laboratory, and tell them if you have a recent infection or inflammation, which can affect the result.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Alpha-1 antitrypsin

Frequently asked questions

Is fasting required for an alpha-1 antitrypsin test?
Fasting is usually not required, although laboratory instructions should be followed. If you have an upcoming procedure, ask the care team whether fasting is needed.
What does a low alpha-1 antitrypsin level mean?
A low level may suggest alpha-1 antitrypsin deficiency. This inherited condition can affect the lungs and liver, so the result may prompt further evaluation.
Can inflammation affect the result?
Yes. Alpha-1 antitrypsin is an acute-phase reactant, so its level can rise during infection or other inflammatory conditions. Your clinician will interpret the result in the context of your health.
  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