Investigation
[Cystic fibrosis]

Chest X-ray

• Increased interstitial reticular markings
• Bronchietasis
• Hilar adenopathy
• Upper lobes are more involved than lower lobes

Lung function tests

• Obstructive pattern

Culture and sensitivity of the sputum

Diagnosis

Diagnosis is confirmed with
   -> sweat test (sweat Na+ >60mmol/L)

If sweat test is abnormal, diagnosis is confirmed.

If the sweat test is normal, but clinically the diagnosis is still suspected, then do genetic testing to confirm/exclude diagnosis.