What is the critical alpha1-antitrypsin level below which lung elastin is attacked and broken down?

a. 57 mg/dl
b. 84 mg/dl
c. 100 mg/dl
d. 150 mg/dl

ANS: A
In the face of a severe deficiency of alpha1-antitrypsin (i.e., when serum levels fall below a "pro-tective threshold" value of 11 µmol/L, or 57 mg/dl), neutrophil elastase may go unchecked, caus-ing breakdown of elastin and resulting dissolution of alveolar walls.