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Alpha-1 Lung Disease: Diagnosis

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This information was reviewed and approved by Karin A. Pacheco, MD, MSPH, Robert A. Sandhaus, MD, PhD, FCCP (11/1/2017).

What tests diagnose Alpha-1?

Alpha-1 antitrypsin blood level, Pi-type or phenotype (structure of the protein made by the Alpha-1 gene), and genotype (testing the Alpha-1 DNA)

In people with Alpha-1 lung disease, the blood level of alpha-1 antitrypsin will often be very low, less than 20 percent of the normal level. The phenotype (Pi-type) of the alpha-1 antitrypsin protein in a person is determined by identifying how the protein moves on an electrified gel. A normal protein is referred to as an M protein. A person with normal alpha-1 antitrypsin proteins is referred to as Pi MM. The most common abnormal proteins are S, Z and F. Sometimes a gene will make no protein; this a “null” gene. When you have two Z genes, you are Pi ZZ, and a person that is most likely to get Alpha-1 lung and/or liver disease. 


Chest radiograph or Chest CT scan

A chest x-ray may reveal that the lungs are hyperinflated due to emphysema. A chest CT will show a pattern of emphysema specific to Alpha-1. When the normal small air sacs (alveoli) of the lungs break down and consolidate, they look like large holes in the lung, like the holes in Swiss cheese. In those who smoke but don’t have Alpha-1, emphysema will occur more frequently in the upper part of the lung. In those with Alpha-1 emphysema, the lower parts of the lung are most commonly affected. Bronchiectasis can occur in those with Alpha-1 lung disease. This is the permanent dilation and thickening of the bronchial tubes from chronic inflammation.

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