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Alpha-1 Antitrypsin, Serum/Plasma — Mass Concentration

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

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

Quick summary

["The result can help identify unusually low or high alpha-1 antitrypsin levels, including possible inherited deficiency."]

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

Key facts at a glance

LOINC
1831-7
Short code
A1AT ZZ SerPl-mCnc
Synonyms
A1AT ZZ SerPl-mCnc
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 concentration 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?

A healthcare professional may order this test if you have unexplained chronic lung disease, liver disease, or a family history of alpha-1 antitrypsin deficiency. It may also be used to follow a person with an abnormal A1AT result.

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. If the level is unexpectedly low, additional testing may be recommended to evaluate the A1AT gene.

How do I prepare for the test?

No special preparation is usually required. Tell your healthcare professional about any medicines or supplements you take, and follow their instructions if this test is being ordered as part of a broader evaluation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An unusually low A1AT level may indicate alpha-1 antitrypsin deficiency, an inherited condition that can increase the risk of emphysema and certain forms of liver disease. A high level may occur with inflammation or infection and does not necessarily indicate a genetic disorder. The result should be interpreted alongside symptoms, medical history, and other tests by a healthcare professional.

Short name

Alpha-1 Antitrypsin (A1AT) Blood Test

Frequently asked questions

What does the A1AT blood test measure?
It measures the amount of alpha-1 antitrypsin in blood. This protein is made mainly by the liver and helps prevent inflammation-related damage to the lungs.
Does a low A1AT result mean I have a genetic condition?
Not always, although a very low level can suggest alpha-1 antitrypsin deficiency. Blood testing may be followed by genetic testing to clarify the result.
Is fasting required for this test?
Fasting is usually not necessary unless your healthcare professional specifically requests it. If you have a scheduled laboratory visit, confirm any preparation instructions beforehand.
  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