Question

Cystic fibrosis characteristically has the following features EXCEPT

• A. Low levels of sodium and chloride in the sweat
• B. Pancreatic insufficiency
• C. Biliary cirrhosis
• D. Bronchial obstruction

Hint:

Recall which way the sweat electrolytes shift in cystic fibrosis, and why that shift is used as a diagnostic test.

Answer 1

The Correct Option is A

This question checks whether you know the direction of the sweat electrolyte abnormality that defines cystic fibrosis.

1. Low levels of sodium and chloride in the sweat: false - CF causes HIGH sweat sodium and chloride because CFTR dysfunction prevents their reabsorption in the sweat duct; this is the basis of the diagnostic sweat test, so this is the correct exception.
2. Pancreatic insufficiency: true - thick secretions obstruct the pancreatic ducts, causing malabsorption.
3. Biliary cirrhosis: true - thickened bile can obstruct bile ducts and lead to liver damage over time.
4. Bronchial obstruction: true - viscous airway mucus is the defining pulmonary problem in CF.

Correct answer: Low levels of sodium and chloride in the sweat.