Alpha-1 Antitrypsin

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Latest Edit: Hector 2014-03-21 (EDT)

See Also Lab Tests

This test is conducted in patients with a family history of emphysema, as there is a tendency of this anti-enzyme to be deficient in such individuals.[1]


  • Alpha-1 antitrypsin, or AAT inactivates endoproteases (protein catabolic enzymes that are released in the body by degenerating and dying cells), such as trypsin and neutrophil elastase.
  • Deficiencies of AAT can be genetic or acquired, where acquired deficiencies can occur in patients with protein-deficiency syndromes (e.g. malnutrition, liver disease, nephrotic syndrome, neonatal respiratory distress syndrome).
  • The major clinical symptoms of AAT deficiency include progressive dyspnea with minimal coughing. Chronic bronchitis and bronchiectasis can be seen in those with AAT deficiency who smoke.

Patient Preparation

  • No fasting required.
  • Factors which can cause increased levels
  • Serum levels of AAT can double during pregnancy.
  • Drugs: Oral contraceptives
  • Factors which can cause decreased levels
  • None noted

Clinical Implications

High levels indicate:

  • Acute and chronic inflammatory disorders
  • Stress
  • Infection
  • Thyroid infections

Low levels indicate:

  • Early onset of emphysema (adults)
  • Neonatal respiratory distress syndrome
  • Cirrhosis
  • Low serum proteins

Associated Tests


  1. Pagana Kathleen D, Pagana Timothy J (2006) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby.