Respiratory System >
Cystic Fibrosis (CF)

“Autosomal recessive mutation causing multisystem disease associated with abnormalities in salt and water transport across epithelial surfaces

Risk Factors
  • Modifiable: n/a
  • Non-Modifiable:
    • Family history of CF
    • Known carrier status of both parents
    • White ethnicity
Aetiology

Mutation in the cystic fibrosis transmembrane regulator (CFTR) gene (commonest mutation is ΔF508)

Pathophysiology

For ΔF508: CFTR misfolds and can’t migrate to cell membrane → ↓ Cl­­- pumped out → ↓ negative regulation of ENac →  Na+ influxes into cell ® water drawn into the cell rather than to mucus →  mucus becomes desiccated and can’t be cleared by ciliary →  neutrophils recruited to clear bacterial colonisation.

Clinical Presentation
  • Infant:
    • Failure to pass meconium and failure to thrive
  • Adults:
    • Wet-sounding cough
    • Recurrent chest infections
    • Chronic sinusitis
    • Steatorrhea
    • Digital clubbing
    • Gastro-oesophageal disease
Investigations
  • Bloods:
    • ↑ Immunoreactive trypsinogen
  • Imaging: n/a
  • Special:
    • Genetic testing – two mutated alleles
    • Sweat test – ↑ Cl
Management
  • Conservative:
    • Chest Physiotherapy
  • Medical:
    • Inhaled bronchodilators (salbutamol)
    • Inhaled mucolytics (dornase alfa, hypertonic saline)
    • Inhaled tobramycin
    • Anti-inflammatories (azithromycin, ibuprofen, prednisolone)
    • CFTR modulators (ivacaftor, lumacaftor)
    • Others: pancreatic enzyme replacement, fat-soluble vitamin supplementation, H2 antagonist/PPI (ranitidine/lansoprazole)
  • Surgical: n/a
Complications
  • Chronic respiratory acidosis
  • Delayed puberty
  • Chronic sinusitis
  • Acute respiratory failure
  • Cor pulmonale
  • Distal intestinal obstructive syndrome
  • Diabetes mellitus
  • Nasal polyps
  • Osteoporosis
  • Advanced liver disease
  • Acute/recurrent pancreatitis

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