Serum Alpha-1 Antitrypsin
Indications
Background
Normal Alpha-1 Antitrypsin Physiology
Synthesis and Circulation of Alpha-1 Antitrypsin
- A1AT is Mainly Synthesized by the Liver: some A1AT is also synthesized locally in the lung by macrophages and bronchial epithelial cells
- A1AT is a 52 kD (394 AA) Glycoprotein Serine Protease Inhibitor (From the “Serpin” Family)
- “Serpinopathies”: collection of neurodegenerative diseases, angioedema-related disorders, and coagulation disorders
- A1AT Synthesized in the Liver Reaches the Lungs Via Diffusion from the Circulation
Normal Alpha-1 Antitrypsin Level
- Normal Serum A1AT Level: 100-300 mg/dL (20-60 µM)
- Threshold (Protective) Serum A1AT Level Below Which There is an Increased Risk of Emphysema: <80 mg/dL (<11 µM)
Normal Biologic Functions of Alpha-1 Antitrypsin
- Inhibition of Pancreatic Trypsin/Chymotrypsin
- Inhibition of Elastase/Granulocytic Elastase: the main site of action is neutrophil elastase
- Inhibition of Collagenase/Synovial and Skin Collagenases
- Inhibition of Microorganism Proteases
Etiology of Elevated Serum Alpha-1 Antitrypsin Level
- General Comments: A1AT is an acute phase reactant, which is increased in a variety of conditions
- Active Vasculitis (see Vasculitis, [[Vasculitis]])
- Following Intravenous Typhoid Vaccine Administration (see Typhoid Fever, [[Typhoid Fever]])
- Infection
- Malignancy
- Pregnancy (see Pregnancy, [[Pregnancy]])
- Severe Burns (see Burns, [[Burns]])
- Tobacco Use (see Tobacco, [[Tobacco]]): smoking elevates the A1AT level approximately 20%
Etiology of Decreased Serum Alpha-1 Antitrypsin Level
References
