A 32-year-old man who smokes 10 cigarettes daily presents with progressive exertional dyspnoea. Spirometry shows airflow obstruction with FEV1/FVC 0.60. CT chest shows bilateral lower-zone panacinar emphysema with minimal upper lobe involvement. His father died of emphysema at age 40. Which investigation will confirm the underlying diagnosis?

• A High-resolution CT guided lung biopsy
• B Bronchoalveolar lavage fluid analysis
• C Diffusion capacity for carbon monoxide alone
• D Serum alpha-1 antitrypsin level with Pi typing ✓

Explanation

Early-onset basal panacinar (panlobular) emphysema in a young smoker with a family history strongly suggests homozygous ZZ alpha-1 antitrypsin deficiency. Diagnosis rests on a low serum AAT level followed by phenotype or genotype (Pi typing) confirmation. DLCO reduction is non-specific and biopsy is unnecessary because the pattern on CT plus serology establishes the diagnosis. All patients should also be counselled on smoking cessation, which accelerates decline markedly.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.