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Cystic fibrosis — RACP Paediatrics MCQ

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ModerateRespiratoryCystic fibrosisRACP Paediatrics

A 7-month-old has recurrent wet cough, poor weight gain and two admissions for lower respiratory infection. He passed meconium at 48 hours and his parents report salty-tasting skin. What is the most appropriate investigation?

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Correct answer: B — Sweat chloride testing with CFTR genetic testing

The history of recurrent chest disease, poor growth, delayed meconium passage and salty skin is suggestive of cystic fibrosis, best investigated with sweat chloride and CFTR testing. IgE testing would be relevant to immediate food allergy but does not explain the neonatal and respiratory features. The pearl is that CF can present despite newborn screening, particularly with atypical genotypes or missed screening.

Reference: RCH Clinical Practice Guidelines: Cystic fibrosis; Australian Newborn Bloodspot Screening Programme