Serum Alpha-1 Antitrypsin



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


  • xxx