4. Cystic Fibrosis (CF)

📄Definition

Cystic Fibrosis is an autosomal recessive genetic disorder caused by mutations in the CFTR gene, leading to defective chloride transport → thick, sticky secretions in the lungs, pancreas, and other organs.

🩺 Physical Examination Findings

  • Bibasal fine end-inspiratory crackles

  • Finger clubbing

  • Signs of pulmonary hypertension in late disease

  • May have features of connective tissue disorder (joint pain, rash, Raynaud’s)

🔎Investigations

🧠 Mnemonic: BLOOM CT

  • Bloods – ANA, RF, ENA, ANCA (connective tissue screen)

  • Lung function tests (↓FVC, ↓DLCO, normal/↑FEV1:FVC)

  • Oxygen saturation (desaturation on exertion)

  • Open lung biopsy (rare – if diagnosis unclear)

  • Microbiology (rule out infection)

  • CT Chest (HRCT = gold standard: shows honeycombing, reticulation, traction bronchiectasis)

  • Testing for causative agents (occupational exposure, drugs, autoimmune)

🧾 Management

🧠 Mnemonic: CLEAN AIRWAYS

  • Chest physiotherapy (daily airway clearance)

  • Long-term antibiotics (e.g. azithromycin)

  • Enzyme replacement (Creon for pancreatic insufficiency)

  • Active lifestyle + high-calorie diet

  • Nebulised bronchodilators + mucolytics (e.g. DNase)

  • Antibiotics for exacerbations (oral/IV based on culture)

  • Insulin for CF-related diabetes

  • Respiratory support if progressive (O₂ / NIV)

  • Women – fertility counselling

  • Avoid smoking exposure

  • Yearly flu + pneumococcal vaccines

  • Specialist CF team coordination

CFTR Modulators (e.g. ivacaftor, lumacaftor–ivacaftor) for eligible genotypes
Lung transplant in end-stage disease

⚠️ Complications

  • Bronchiectasis

  • Respiratory failure

  • Infertility (esp. males)

  • Diabetes

  • Osteoporosis

  • Liver disease

  • Intestinal obstruction

  • Pneumothorax

  • Haemoptysis

  • Depression, social impact

🧐Differentials

🧠 Mnemonic: SAME FAIL

  • Severe asthma

  • Allergic bronchopulmonary aspergillosis (ABPA)

  • Meckel’s diverticulum (if bowel obstruction)

  • Enteropathy

  • Foreign body inhalation

  • Alpha-1 antitrypsin deficiency

  • Immunodeficiency

  • Lung malformations

📌 PARA Revision Tips

  • Gold standard test = sweat chloride

  • Most common bug = Pseudomonas aeruginosa

  • Know Creon, airway clearance, and CFTR modulator therapy

  • Meconium ileus in newborns = suspect CF

  • Discuss genetic inheritance and screening

🔎 Last updated in line with NICE NG78 (2017), reviewed 2023
Last reviewed: July 2025
🔒 PASSMAP ensures all content is NICE-aligned and reviewed for Physician Associate Registration Assessment (PARA) success.

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