Cystic Fibrosis

Question 1

CYSTIC FIBROSIS

Answer 1

• Increased Viscosity and Tenacity of Epithelial Mucus; Classical form presents with
Bronchopulmonary infections and Pancreatic Insufficiency with High Sweat Na+
and Cl-
• Autosomal Recessive disorder with carrier frequency of 1 in 22 in Caucasians
• Gene Mutation affecting 7q31.2; Most commonly ΔF508 Deletion (70%) resulting in Defect in
CF Transmembrane Conductance Regulator (CFTR) leads to failure of opening of Chloride
Channel in response to cAMP
o Decreased Chloride excretion into airway lumen and Increased Sodium reabsorption
into Epithelial cells results in less excretion of salt
o Less excretion of Water leads to increased viscosity
• Progressive Respiratory Failure; Life expectancy about 40yrs
• Infection with Burkholderia cepacia associated with accelerated disease and rapid death

Question 2

Presentation of Cystic Fibrosis

Answer 2

• Lungs structurally normal at birth but develops frequent respiratory infections; Commonest
cause of Recurrent Bronchopulmonary Infection in childhood
• Sinusitis and Nasal Polyps are common; SOB and Haemoptysis as Airflow Limitation and
Bronchiectasis develops
• Spontaneous Pneumothorax, Respiratory failure and Cor Pulmonale might develop
• Meconium Ileus due to Meconium viscosity; Might develop Meconium Ileus Equivalent
Syndrome later in life (Small Intestinal Obstruction)
• Symptomatic Steatorrhoea (85% of patients) due to Pancreatic Insufficiency
• Cholesterol Gallstones with increasing frequency, Cirrhosis (5% of patients) and increased
incidence of Peptic Ulcers and GI Malignancy
• Malnutrition due to Malabsorption/Maldigestion; Associated with risk of pulmonary sepsis
o Puberty and Skeletal Maturity delayed in most CF patients
o Males infertile due to failure of Vas Deferens and Epididymis development
o Females might be able to conceive but secondary amenorrhoea as disease progresses

Question 3

Investigations for Cystic Fibrosis

Answer 3

• Establish Family History, Blood DNA Analysis of gene defect
• High Sweat Sodium Concentration (>60mmol/L)
• CXR Bronchiectasis
• Absent Vas Deferens and Epididymis
• Blood Immunoreactive Trypsin Levels for screening

Question 4

Treatment of Cystic Fibrosis

Answer 4

• Smoking cessation, Influenza and Pneumococcal Vaccination, Pulmonary Rehabilitation
• Oxygen Therapy as needed; Antibiotic therapy for infections
o Non-invasive O2 therapy as bridge to surgery
• Nebulised Anti-Pseudomonas antibiotic therapy (e.g. Piperacillin)
• β2 Agonists and Inhaled Corticosteroids for symptomatic relief
• Inhaled Dornase Alfa (Recombinant DNAse) and Hypertonic saline for short term benefit;
Acetylcysteine and Amiloride (Inhibits ENaC) have poor results
• Treatment for Pancreatic Insufficiency (e.g. Creon) and Malnutrition