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Alpha-1 Antitrypsin (A1AT) Serum Protein Level

Published: August 9, 2026Updated: August 17, 2026

This test measures the amount of Alpha-1 Antitrypsin, a protein produced by the liver that helps protect the lungs from damage caused by enzymes released during inflammation.

Quick summary

["A1AT helps prevent lung disease; low levels may indicate genetic risk or liver issues."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
105927-8
Short code
M tb DNA Stl Ql NAA+probe
Synonyms
M tb DNA Stl Ql NAA+probe
Category
chemistry
Sample
stool
Container
Clean container
Units
N/A
Ref low
10
Ref high
40
Critical range
— – 500 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
probe-amp-tar
CPT
84484
SNOMED
302774002
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your doctor may order this test if you have symptoms like chronic cough, shortness of breath, or if you have a family history of lung diseases like emphysema or chronic obstructive pulmonary disease (COPD). It’s also used to check for liver problems or to monitor conditions like alpha-1 antitrypsin deficiency.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. If you’re on blood thinners, let your doctor know before the test.

What the Results Mean

Results help determine if your A1AT levels are low or high. Low levels may suggest genetic disorders or liver disease, while high levels could indicate certain liver conditions or inflammation.

Common Conditions Linked to A1AT Levels

Low A1AT levels are often linked to alpha-1 antitrypsin deficiency, which can cause lung diseases or liver problems. High levels may be seen in conditions like hepatitis or certain types of liver disease.

Reference range

Adult: 10-40 U/LN/A

Specimen: stool

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

A1AT Level

Frequently asked questions

What causes low Alpha-1 Antitrypsin levels?
Low A1AT levels can be due to genetic mutations (alpha-1 antitrypsin deficiency), liver disease, or certain medications. If you have a family history of lung or liver disease, your doctor may recommend testing.
How often should I get this test?
Your doctor will decide how often you need this test based on your health history, symptoms, and risk factors. Regular monitoring may be needed if you have a genetic condition or related symptoms.
Can diet or lifestyle changes affect A1AT levels?
Diet and lifestyle factors like smoking, alcohol use, or certain medications may influence liver function indirectly, but they don’t directly change A1AT levels. Avoid smoking and limit alcohol to support overall 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 17, 2026. · Read our editorial policy