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Cystic fibrosis — RACP Paediatrics MCQ

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EasyRespiratoryCystic fibrosisRACP Paediatrics

A 4-month-old presents with recurrent lower respiratory tract infections and failure to thrive. There is a history of meconium ileus at birth and the stools are described as greasy and offensive. What is the most appropriate investigation?

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Correct answer: B — Sweat test

The combination of recurrent chest infections, failure to thrive, meconium ileus, and steatorrhoea is highly suggestive of cystic fibrosis. The sweat test (pilocarpine iontophoresis) remains the gold standard diagnostic investigation. A chloride level ≥60 mmol/L is diagnostic.

Reference: RCH Melbourne – 2023 – Cystic Fibrosis CPG; Australian Therapeutic Guidelines – 2024 – Respiratory