Alpha-1-Antitrypsin (AAT), Serum Test
Test Overview
The Alpha-1-Antitrypsin (AAT), Serum Test measures the level of alpha-1-antitrypsin protein in the blood. AAT is a protective protein produced mainly by the liver that helps protect the lungs and other tissues from enzyme-related damage.
This test is commonly used to diagnose Alpha-1-Antitrypsin Deficiency, a genetic disorder associated with lung disease, liver disease, and chronic respiratory problems.
Why This Test is Done
- Evaluate suspected AAT deficiency
- Investigate early-onset COPD or emphysema
- Assess unexplained liver disease
- Family screening for inherited AAT deficiency
- Monitor chronic lung or liver conditions
Clinical Significance
Alpha-1-antitrypsin acts as a protease inhibitor, especially against neutrophil elastase in the lungs.
Low levels may increase the risk of:
- Emphysema
- Chronic Obstructive Pulmonary Disease (COPD)
- Chronic bronchitis
- Liver cirrhosis
- Neonatal hepatitis
- Panniculitis
Specimen Required
-
Sample Type: Serum
-
Collection Tube: Plain red-top tube / serum separator tube
-
Preparation: No fasting required
Method
- Immunoturbidimetry
- Nephelometry
- Immunoassay
Reference Range
-
90 – 200 mg/dL
(Reference values may vary slightly depending on laboratory method.)
Interpretation
Decreased AAT Levels
May indicate:
- Alpha-1-antitrypsin deficiency
- Liver disease
- Nephrotic syndrome
- Protein-losing enteropathy
- Severe malnutrition
Increased AAT Levels
May be seen in:
- Acute inflammation
- Infection
- Pregnancy
- Estrogen therapy
- Tissue injury
Symptoms Suggesting AAT Deficiency
- Shortness of breath
- Wheezing
- Chronic cough
- Recurrent respiratory infections
- Fatigue
- Jaundice or liver dysfunction
Additional Notes
- AAT is an acute phase reactant, so levels can rise during inflammation.
- Low results may require phenotyping or genetic testing for confirmation.
- Family members of affected individuals may benefit from screening.
Turnaround Time
Useful For
- Pulmonologists
- Hepatologists
- Dermatologists
- Internal Medicine Specialists
- Genetic screening programs
