ما الفحص الأساسي لتشخيص التليف الكيسي؟

What is the key diagnostic test for cystic fibrosis?

1. Serum iron studies
2. Sweat chloride test
3. A 12-lead ECG
4. A urine culture

Answer: B) Sweat chloride test. The sweat chloride test is the key test, with a high result supporting the diagnosis alongside genetic testing. Newborns may present with meconium ileus.