Asthma USMLE Step 1 Practice Question
A 9-year-old boy with neonatal meconium ileus presents with recurrent pneumonia, chronic productive cough, steatorrhea, and poor weight gain. Vital signs: HR 102/min, RR 24/min, SpO2 94% on room air. Chest X-ray shows bronchiectasis with bronchial wall thickening. Sweat chloride test is markedly elevated at 85 mEq/L. He denies hemoptysis. He currently takes pancreatic enzymes and albuterol as needed. Which pathophysiologic mechanism best explains his progressive pulmonary disease?
Answer choices
- AIgA deficiency causing recurrent mucosal infection only
- BType I pneumocyte destruction causing diffuse alveolar collapse
- CThick dehydrated secretions causing airway obstruction and recurrent infectionCorrect answer
- DDefective dynein arms causing impaired ciliary motility
- ELoss of dystrophin causing weak respiratory muscles
- FAlpha-1 antitrypsin deficiency causing protease-antiprotease imbalance and progressive airway destruction
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