S-alpha1-Antitrypsin (S-Antitrypsin) is an acute phase protein produced in the liver and plays an important role in protecting the body's tissues from enzymatic degradation. It acts as an inhibitor of elastase, an enzyme released by neutrophils during inflammation, thereby preventing damage to the lungs and other tissues. Alpha-1-antitrypsin is an important marker in the assessment of inflammatory processes, genetic diseases, and liver damage.
What is the function of Antitrypsin in the body?
As part of the body's defense mechanisms, alpha-1-antitrypsin regulates the activity of proteolytic enzymes and prevents the breakdown of supporting tissues. The protein is particularly important in protecting the lungs from damage caused by inflammation. In cases of genetic deficiency, protein levels may be insufficient to protect the lungs and liver, which can lead to the development of disease.
- Protease inhibitors prevent elastase from breaking down lung tissue and other structures.
- Acute phase reactant increases in systemic inflammation, infection, and liver disease.
- Liver-related biomarker levels are affected by both acute and chronic liver disease.
When is Antitrypsin tested in healthcare?
The analysis of S-alpha1-Antitrypsin is used to diagnose and monitor several medical conditions. It is particularly important in cases of suspected genetic alpha-1-antitrypsin deficiency, a disease that can lead to COPD and liver damage. The test is also used as a marker of inflammation and in the assessment of liver disease.
- Alpha-1-antitrypsin deficiency is suspected in early-onset emphysema or COPD, especially in nonsmokers.
- Inflammatory diseases are increased in systemic inflammatory conditions, such as autoimmune diseases.
- Liver diseases in chronic liver damage, including cirrhosis and hepatitis.
- Treatment monitoring: to follow the course of the disease in patients with alpha-1-antitrypsin deficiency.
Smoking and antitrypsin deficiency
It is well known that individuals with severe alpha-1-antitrypsin deficiency (AAT deficiency) who smoke develop emphysema significantly earlier than smokers with normal AAT levels. Alpha-1-antitrypsin occurs in several posttranslationally modified forms, some of which lack antiprotease activity. Inhaled and endogenously produced factors that modify antitrypsin are believed to lead to functional AAT deficiency, resulting in the development of COPD/emphysema.
Reference values and interpretation of S-alpha1-Antitrypsin
Reference values for S-alpha1-Antitrypsin vary somewhat between different laboratories but are usually between 0.9 – 2.0 g/L for healthy adults.
Elevated values of S-alpha1-Antitrypsin
- Inflammatory processes and infections
- Acute and chronic liver disease
- Oestrogen therapy (birth control pills, hormone therapy, pregnancy)
- Autoimmune diseases
- Certain malignant diseases
Low values of S-alpha1-Antitrypsin
- Genetic alpha-1-antitrypsin deficiency (PiZZ genotype gives the lowest levels)
- Liver failure with impaired protein synthesis
- Nephrotic syndrome (loss of plasma proteins via the urine)
- Malnutrition or severe malnutrition
Clinical relevance
S-alpha1-Antitrypsin is an important biomarker in both liver diagnostics and inflammation studies. Since it is an acute phase protein, it can increase in various disease states, but to investigate genetic deficiency it is important that the sample is taken when the patient does not have ongoing inflammation. When alpha-1-antitrypsin deficiency is suspected, complementary analyses such as phenotyping, genotyping and isoelectric focusing are often used to confirm the diagnosis.