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Borderline Sweat Chloride — RACP Paediatrics MCQ

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HardRespiratoryBorderline Sweat ChlorideRACP Paediatrics

An 8-year-old presents with a chronic productive cough, recurrent sinusitis, and nasal polyps. Sweat chloride is borderline at 45 mmol/L. What should be done next?

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Correct answer: C — Repeat sweat test and consider extended CFTR gene mutation analysis

Sweat chloride 30-59 mmol/L is intermediate and requires further investigation: repeat sweat test and CFTR gene analysis (extended mutation panel or sequencing). Nasal polyps in a child are unusual and should raise suspicion for CF. NPD (nasal potential difference) or ICM (intestinal current measurement) may help in equivocal cases.

Reference: Australian Cystic Fibrosis Guidelines – 2024 – Diagnosis