Cystic Fibrosis Flashcards
What is cystic fibrosis?
An inherited disease affecting multiple organs.
A genetic mutation results in thickened secretions which commonly leads to recurrent respiratory infections.
Epidemiology
CF is the most common inherited disease in Caucasians.
In the UK there are around 10,600 cases, whereas worldwide there are thought to be around 100,000.
What is the inheritance pattern in CF?
Autosomal recessive
What mutation causes CF?
Chromosome 7 in the CF transmembrane conductance regulator (CFTR) gene.
The most common mutation found in Caucasians is delta-F508 (DF508).
What is the impact of the mutation on chromosome 7 in CF?
CFTR allows efflux of chloride and inhibits influx of sodium.
This keeps sodium and chloride in the lumen, out of the cells.
In CF, increased sodium absorption and abnormal chloride secretion leads to thicker mucus impairing the function of cilia.
What is a risk factor of CF?
Family history
Clinical Features
CF has effects on multiple systems but most commonly presents with respiratory effects.
Present at any age but usually found in new born screening
What does CF cause?
Thickened secretions from lungs
Reduce mucociliary clearance from the bronchi and increased salt concentration leads to impaired bacterial defences.
Subsequently, bacterial colonisation and lung inflammation increases, which can present as recurrent lower respiratory tract infections and bronchiectasis.
Neonatal features
Failure to thrive
Meconium Ileus - bowel obstruction
Rectal prolapse
Respiratory features
Chronic Sinusitis
Nasal Polyps - painless soft growths inside your nose
Symptoms including cough, wheeze, haemoptysis
Recurrent lower respiratory tract infections
Bronchiectasis
Pneumothorax
Cor pulmonale
Respiratory failure
Reproductive features
Male infertility
Diagnosis
Neonatal heel prick day between day 5 and day 9
Sweat test: measure chloride concentration >60mmol/L is abnormal
Faecal elastase: this can provide evidence for abnormal pancreatic exocrine function.
Genetic screening: This can identify CF mutations
History
Respiratory: frequency of infections, cough, sputum (colour, amount), haemoptysis, breathlessness
Pancreatic function: failure to thrive, steatorrhoea, thirst, polyuria
Gastrointestinal: abdominal pain, bloating, vomiting
Difficulty conceiving and irregular menstruation
Medical management
Infective exacerbations
Antibiotics, although for patients with recurrent chest infections prophylactic long-term antibiotics may be prescribed.
Nebulised mucolytics (Dornase Alfa)
Bronchodilators (Inhaled corticosteroids or B2-agonists)
Worsening progressive lung disease is treated with:
Oxygen
Non invasive ventilation
Diuretics if signs of cor pulmonale
