Which factor causes lower-lobe emphysema?

Which factor causes lower-lobe emphysema?

• A. Smoking
• B. Alpha-1 Antitrypsin Deficiency
• C. Hepatic Endoplasmic Reticulum
• D. Bronchodilator

Answer: (B)

Lower-lobe emphysema is classically seen with alpha-1 antitrypsin deficiency. This genetic condition leads to reduced inhibition of neutrophil elastase in the lungs, allowing elastase to destroy elastic tissue in the alveolar walls across the acinus. The resulting pattern is panacinar and tends to be more pronounced in the lung bases, so the lower lobes are preferentially affected, often presenting at a younger age than smoking-related disease. Smoking can cause emphysema too, but it usually produces a different pattern—centrilobar emphysema with upper-lobe predominance. The hepatic endoplasmic reticulum is related to how the deficiency develops (the protein is made in the liver and misfolded variants can accumulate there), but it is not the direct cause of lower-lobe emphysema. A bronchodilator is a treatment, not a cause.

Lower-lobe emphysema is classically seen with alpha-1 antitrypsin deficiency. This genetic condition leads to reduced inhibition of neutrophil elastase in the lungs, allowing elastase to destroy elastic tissue in the alveolar walls across the acinus. The resulting pattern is panacinar and tends to be more pronounced in the lung bases, so the lower lobes are preferentially affected, often presenting at a younger age than smoking-related disease. Smoking can cause emphysema too, but it usually produces a different pattern—centrilobar emphysema with upper-lobe predominance. The hepatic endoplasmic reticulum is related to how the deficiency develops (the protein is made in the liver and misfolded variants can accumulate there), but it is not the direct cause of lower-lobe emphysema. A bronchodilator is a treatment, not a cause.