AAT levels are primarily used when assessing a diagnosis of acute hereditary AAT deficiency as a cause of neonatal hepatitis accompanied by progressive liver cirrhosis in early childhood, or
when severe pulmonary emphysema occurs in adults due to the prevalence of leukocyte elastase, which can lead to unrestrained proteolytic degradation of the pulmonary parenchymal cells.

Samples with low AAT levels are referred for AAT phenotyping to exclude hereditary AAT deficiencies.