Introduction
A chronic lung disease in a child usually shows as a wet cough lasting more than 4 weeks, recurrent chest infections, poor growth or finger clubbing. The main causes are cystic fibrosis, primary ciliary dyskinesia, bronchiectasis from other causes, bronchopulmonary dysplasia, and congenital lung malformations.
Cystic fibrosis (CF)
The commonest lethal autosomal recessive disease in white populations (about 1 in 2500–3500 births). Mutations in the CFTR gene (chromosome 7; commonest F508del) break a chloride channel in epithelial cells. Secretions become thick and sticky, and blocked ducts and airways become inflamed and infected.
Diagnosis
- Newborn screening: raised immunoreactive trypsinogen (IRT) in the heel-prick blood, then CFTR mutations.
- Sweat test chloride ≥ 60 mmol/L confirms CF (30–59 is borderline).
- Genetic testing; faecal elastase for the pancreas.
Treatment
- Daily airway clearance physiotherapy and exercise; inhaled dornase alfa and hypertonic saline to thin mucus.
- Antibiotics for exacerbations; inhaled tobramycin or colistin against Pseudomonas; azithromycin.
- CFTR modulators (elexacaftor–tezacaftor–ivacaftor) correct the faulty protein for most mutations and have changed the outlook.
- Pancreatic enzymes with every meal, high-calorie high-fat diet, vitamins A, D, E, K, extra salt. Lung transplant at end stage.