The association between α1-antitrypsin deficiency and heritable emphysema was discovered in 1963. Subsequent epidemiologic evidence suggested that a serum α1-antitrypsin level of 11μmol/L (about 80 mg/dL by the still-used “commercial standard”), which is about 35% of the normal level, represents a “threshold” value, below which the risk of developing emphysema is increased and above which the emphysema risk is not increased. Recently, the ability to isolate and purify the α1-antitrypsin protein from human blood has made “specific” augmentation therapy possible. Intravenous infusion of α1- antitrypsin raises serum and alveolar levels above the putative thresholds, but clinical efficacy (ie, decreased rate of decline in lung function and/or improved survival) remains presumptive. Based on available evidence, the American Thoracic Society recommends augmentation therapy for individuals with both a documented severe deficiency of α1-antitrypsin and fixed airflow obstruction.
© Lippincott-Raven Publishers.