Which pulmonary function tests are indicated in the workup of alpha1-antitrypsin deficiency (AATD)?

Updated: Sep 11, 2020
  • Author: Dora E Izaguirre Anariba, MD, MPH; Chief Editor: John J Oppenheimer, MD  more...
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Answer

The severity of emphysema is best documented with standard pulmonary function tests. Spirometric determination of forced vital capacity (FVC) and forced expired volume in 1 second (FEV1) are essential. Determining lung volume (preferably by plethysmography) and measuring diffusing capacity provide additional valuable information.

Patients who are symptomatic at the time of diagnosis usually have moderate-to-severe airflow obstruction with an FEV1 in the range of 30-40% of the predicted value. Reduced vital capacity and increased lung volumes secondary to air trapping (residual volume >120% of predicted value) are usually present. Diffusing capacity values are reduced substantially (<50% of predicted value) in most symptomatic patients.

Alpha1-antitrypsin-deficient individuals who are identified by screening programs or because a relative has been diagnosed with the disease may have few or no abnormalities.


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