Viral Hepatitis and Liver Disease Website Course

Evaluating Liver Test Abnormalities

Understanding the Pathophysiology of Liver Disease

for Health Care Providers

Alpha-1 Antitrypsin Deficiency

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Alpha-1 antitrypsin (AAT) is a protease inhibitor of the enzyme elastase. In lungs, AAT deficiency leads to progressive fibrosis. In liver, there is a polymerization and accumulation of an abnormal variant of AAT, leading to hepatocellular injury.

There are no physical findings diagnostic of AAT deficiency. The initial test is serum AAT level. Genetic phenotyping is used to confirm the diagnosis of alpha-1 antitrypsin deficiency if serum AAT is low.