Alpha-1 Antitrypsin
Also known as: A1AT, AAT
What Does Alpha-1 Antitrypsin Measure?
Alpha-1 Antitrypsin (A1AT or AAT) is a protein produced primarily by the liver that circulates in the bloodstream. This test measures the concentration of A1AT in your blood to assess whether your body is producing enough of this protective protein. A1AT belongs to a family of proteins called serine protease inhibitors (serpins), and its primary job is to neutralize neutrophil elastase — an enzyme released by white blood cells during infection and inflammation that can break down lung tissue if left unchecked.
Why Does Alpha-1 Antitrypsin Matter?
A1AT is critically important for protecting the lungs and other tissues from damage caused by enzymes released during immune responses. When A1AT levels are too low — due to a genetic condition called Alpha-1 Antitrypsin Deficiency (AATD) — the lungs become vulnerable to destruction, increasing the risk of early-onset emphysema and chronic obstructive pulmonary disease (COPD), especially in smokers. The liver can also be affected because abnormal A1AT protein can accumulate in liver cells, leading to hepatitis, cirrhosis, and in some cases liver cancer. Measuring A1AT levels is essential for diagnosing AATD, evaluating unexplained lung or liver disease, and guiding treatment decisions including augmentation therapy.
Normal Ranges
Males
100–200 mg/dL (approximately 20–53 µmol/L)
Females
100–200 mg/dL (approximately 20–53 µmol/L)
Children
Varies by age; newborns typically 145–270 mg/dL, decreasing toward adult ranges by early childhood
Causes of High Levels
- Acute or chronic inflammation and infection (A1AT is an acute-phase reactant that rises during inflammatory states)
- Pregnancy, particularly in the second and third trimesters due to estrogen-driven liver protein synthesis
- Use of oral contraceptives or estrogen-containing hormone therapy
- Rheumatoid arthritis and other autoimmune conditions causing systemic inflammation
- Certain cancers, especially lymphomas and liver tumors, which can stimulate abnormal protein production
- Tissue injury or surgery, which triggers an acute-phase response elevating liver-produced proteins
Causes of Low Levels
- Alpha-1 Antitrypsin Deficiency (AATD) — an inherited genetic disorder caused by mutations in the SERPINA1 gene, most commonly the Z and S alleles
- Severe liver disease such as cirrhosis, which impairs hepatic protein synthesis
How to Improve Your Alpha-1 Antitrypsin
Diet
- Eat a high-protein diet (1.2–1.5 g/kg body weight per day) including lean meats, eggs, legumes, and dairy to support liver protein synthesis
- Consume antioxidant-rich foods such as berries, leafy greens, and cruciferous vegetables to reduce lung oxidative stress
- Avoid or minimize alcohol intake, as alcohol accelerates liver damage in individuals with low A1AT or liver accumulation of abnormal A1AT protein
- Include anti-inflammatory foods such as fatty fish (salmon, mackerel), olive oil, and turmeric to reduce overall systemic inflammation
- Maintain adequate zinc intake through foods like pumpkin seeds, oysters, and legumes, as zinc supports proper A1AT protein folding and secretion
Supplements
- Zinc supplementation (15–30 mg/day) may help promote proper A1AT secretion from liver cells in some AATD genotypes — consult a physician before use
- Vitamin D (1000–2000 IU/day) to support immune regulation and lung health, particularly important in COPD-related AATD
- N-Acetylcysteine (NAC, 600 mg twice daily) as an antioxidant to protect lung tissue from oxidative damage — evidence is emerging but promising
- Omega-3 fatty acids (2–4 g/day EPA+DHA) to reduce systemic inflammation and protect lung and liver tissue
Related Biomarkers
Frequently Asked Questions
What is Alpha-1 Antitrypsin Deficiency and how common is it?
Alpha-1 Antitrypsin Deficiency (AATD) is a hereditary condition caused by mutations in the SERPINA1 gene that result in insufficient or dysfunctional A1AT protein. It affects approximately 1 in 2,500 to 1 in 5,000 individuals of European descent, making it one of the most common serious genetic disorders. Many people remain undiagnosed for years because symptoms mimic other lung and liver conditions. The most severe form (ZZ genotype) produces A1AT levels below 35 mg/dL, which offers almost no protection to the lungs.
Can a high A1AT result be a sign of disease?
Yes. Because A1AT is an acute-phase reactant, elevated levels indicate that the body is responding to inflammation, infection, injury, or certain hormonal changes. A high result does not typically cause direct harm itself, but it signals an underlying condition — such as an active infection, autoimmune disease, or cancer — that requires investigation. High A1AT during pregnancy or oral contraceptive use is generally considered a normal physiological response. Your doctor will interpret elevated levels in the context of your full clinical picture.
How is Alpha-1 Antitrypsin Deficiency diagnosed beyond a blood level test?
A low A1AT blood level is the first indicator, but genotyping or phenotyping is required to confirm AATD. Genotyping (DNA testing) identifies specific mutations in the SERPINA1 gene, such as the common Z and S alleles. Phenotyping (isoelectric focusing or ELISA) identifies the actual A1AT protein variants present. Pulmonary function tests help assess lung damage, and liver biopsy or imaging may be used to evaluate liver involvement. A comprehensive diagnosis typically involves a pulmonologist and/or hepatologist.