Cystic Fibrosis in Children

Definition and epidemiology

Cystic fibrosis (CF) is an autosomal-recessive multisystem disorder caused by mutations in the CFTR gene, which encodes a cAMP-regulated chloride/bicarbonate channel. Defective ion transport produces thick, dehydrated secretions affecting the lungs, pancreas, intestine, hepatobiliary tract, sweat glands, and vas deferens. CF is commonest in populations of European ancestry (~1 in 2,500–3,500 births); it is under-recognised in India, where consanguinity, a wider mutation spectrum (F508del less dominant), and diagnostic delay are well documented, so a high index of suspicion is essential.

Clinical features

CF is a multisystem disease — presentation varies by age:

• Respiratory: chronic wet cough, recurrent/persistent infections (Staph aureus, Pseudomonas), bronchiectasis, nasal polyps, sinusitis, digital clubbing
• Gastrointestinal/nutritional: pancreatic insufficiency with steatorrhoea, failure to thrive despite good appetite, fat-soluble vitamin (A, D, E, K) deficiency
• Neonatal: meconium ileus (≈15–20%), prolonged neonatal jaundice
• Other: distal intestinal obstruction syndrome, rectal prolapse, CF-related liver disease, salt-loss/hyponatraemic dehydration (a heat-prone clue in India), CF-related diabetes, and male infertility (CBAVD)

Diagnosis

Diagnosis requires clinical features, a positive newborn screen, or a family history, PLUS evidence of CFTR dysfunction. The sweat chloride test (pilocarpine iontophoresis) is the cornerstone: ≥60 mmol/L is diagnostic, <30 mmol/L makes CF unlikely, and 30–59 mmol/L is intermediate — repeat and proceed to extended CFTR gene analysis and/or CFTR functional testing. Sweat testing is best performed after 10 days of age in infants >36 weeks and >2 kg.

See the full criteria: Cystic Fibrosis Diagnosis

Red flags

• Meconium ileus or unexplained neonatal bowel obstruction
• Failure to thrive with steatorrhoea and a voracious appetite
• Recurrent/persistent lower-respiratory infection, especially Pseudomonas colonisation
• Hyponatraemic, hypochloraemic metabolic alkalosis (pseudo-Bartter) — common in hot climates
• A sibling with CF or unexplained childhood death
• Nasal polyps in a young child

Management overview

CF care is multidisciplinary and lifelong, ideally at a specialist CF centre:

1. Airway clearance — physiotherapy plus inhaled mucolytics (hypertonic saline, dornase alfa).
2. Infection control — segregation, aggressive antibiotics for exacerbations, Pseudomonas eradication, and chronic suppressive inhaled antibiotics.
3. Nutrition — pancreatic enzyme replacement, high-calorie diet, fat-soluble vitamin supplementation, and salt replacement.
4. CFTR modulators (e.g. elexacaftor/tezacaftor/ivacaftor) for eligible genotypes — transformative but access is limited and costly in India.
5. Surveillance for CF-related diabetes, liver disease, bone health, and mental health.
6. Genetic counselling for the family and carrier testing.

References

• CF Foundation Diagnosis Consensus Guidelines (2017)
• CF Foundation Sweat Test Clinical Care Guidelines
• ECFS Standards of Care
• IAP/ICMR CF guidance

Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.