Which statement about cystic fibrosis is true?

• A. Sticky thick respiratory secretions
• B. Weight gain is typical
• C. SpO2 is always normal
• D. No risk of infections

Answer: (A)

In cystic fibrosis, the defect in the CFTR channel causes less water and chloride to move into the airway surfaces, so the mucus becomes thick and sticky. That stickiness makes it hard for cilia to clear secretions, leading to mucus plugging, airflow obstruction, and a high risk of recurrent bacterial infections. This thick, sticky mucus is the true statement because it directly reflects the basic pathophysiology of CF and explains many of the clinical features you see, like chronic cough and frequent lung infections.

Weight gain is not typical in CF; many patients struggle with pancreatic insufficiency, leading to malabsorption and poor weight gain unless enzyme therapy and nutrition support are used. SpO2 is not guaranteed to be normal—oxygen saturation can drop during pulmonary infections or exacerbations, even though resting values might appear normal in milder cases. And there is a high risk of infections in CF, not no risk—chronic colonization with organisms such as Pseudomonas aeruginosa is common and contributes to ongoing lung damage.