A 34-year-old male smoker presents with progressive exertional dyspnea. CT chest shows basal-predominant panacinar emphysema out of proportion to his 8 pack-year history. Liver tests show mild transaminase elevation. Which investigation will confirm the underlying cause?
- A Bronchoalveolar lavage for CD4/CD8 ratio
- B Sweat chloride estimation
- C Serum alpha-1 antitrypsin level with PI typing ✓
- D Serum angiotensin converting enzyme level
Correct answer: C. Serum alpha-1 antitrypsin level with PI typing
Explanation
Early-onset basal panacinar emphysema in a light smoker, especially with liver involvement, points to homozygous (PiZZ) alpha-1 antitrypsin deficiency. Unopposed neutrophil elastase destroys lung elastin while polymerised AAT accumulates in hepatocytes causing cirrhosis. A low serum level with PiZZ typing confirms it. Sweat chloride tests for cystic fibrosis, ACE is a nonspecific marker in sarcoidosis, and BAL lymphocyte subsets relate to hypersensitivity pneumonitis and sarcoidosis.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.