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Alpha-1 Antitrypsin, Serum/Plasma — Mass Concentration

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

A blood test that measures alpha-1 antitrypsin protein, mainly used to evaluate low levels and possible inherited deficiency.

Quick summary

["Low alpha-1 antitrypsin levels may indicate an inherited deficiency that can affect the lungs and liver."]

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

Key facts at a glance

LOINC
1825-9
Short code
A1AT SerPl-mCnc
Synonyms
A1AT 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 blood test measures the amount of alpha-1 antitrypsin (A1AT) protein in serum or plasma. A1AT is an enzyme that helps protect the lungs from inflammation and helps limit damage to the liver.

Why might I need this test?

The test may be ordered for unexplained chronic lung disease, including emphysema or chronic bronchitis, especially in younger people. It may also be used when liver disease is suspected or when another affected family member has a low A1AT level.

How is the test performed?

A blood sample is collected, and the laboratory measures the concentration of A1AT in the serum or plasma. Additional genetic or protein testing may be recommended if the result is low or if a hereditary deficiency is suspected.

How do I prepare for the test?

No special preparation is usually required. Tell your healthcare professional if you have a recent infection, inflammation, or liver disease, because these conditions can change the A1AT level and may affect interpretation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Alpha-1 Antitrypsin (A1AT)

Frequently asked questions

Does a low A1AT result mean I have emphysema?
No. A low result may indicate A1AT deficiency, but it does not by itself diagnose emphysema or other lung disease. Your healthcare professional will interpret the result alongside your symptoms, medical history, and other tests.
Can inflammation make the A1AT level look normal?
Yes. A1AT is an acute-phase reactant, so its level can rise during infection, inflammation, or pregnancy. A result obtained during one of these situations may need to be repeated after the condition has resolved.
What happens if alpha-1 antitrypsin deficiency is confirmed?
Your healthcare professional may recommend lung function testing, liver evaluation, lifestyle changes such as avoiding smoking, and sometimes vaccinations or specialized treatments. Genetic counseling may also be appropriate for family members.
  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