Cystic Fibrosis Flashcards
What’s the definition of Cystic fibrosis?
Autosomal recessive disease by mutation of chlorine channel gene leading to hyperviscous secretions.
What’s the background of Cystic fibrosis?
Common genotype in 80% - phenylalanine deletion at chromosome 7q positon 508, coding for abnormal transporter CFTR.
Pathophysiology: Low Cl- and Na+ transport out of cells. This fails to drag water across into mucus secretions, leading to hyperviscosity. Lung is normal at birth but then secretions become viscous. Patients get recurrent Staph areus, H. Inf and Pseudomonas infecitons due to impaired clearance. Pancreatic insufficiency causing early DM, malabsorption and steathorrea due to reduced enzyme delivery.
Epidemiology
1/2500 live births, 1/25 carriers.
What would you see on history and exam in Cystic fibrosis?
Neonatal: 15% have meconium ileus
Infancy: recurrent chest infections and failure to thrive, delay.
Older: asthma, ABPA (brown sputum with fever and wheeze), sinusitis.
Signs of malnutrition: low muscle mass
Clubbing, hyperinflation, coarse crepitaitons, expiratory rhonchi.
May have jaundice, nasal polyps and rectal prolapse.
What investigations would you use in Cystic fibrosis?
Sweat test is gold standard, low Na and Cl in sweat.
Lung function: obstructive, low FVC and low FEV FVC ratio.
Guthrie’s test: high serum immunoreactive trypsin
Antenatal test: first trimester CVS / second trimester low intestinal ALP in amniotic fluid.
What is the management of Cystic fibrosis?
Respiratory: Flucox prophylaxis, nebulized antibiotics (colomycin) when pseudomonas infection, ABPA requires steroids and itraconazole, bronchodilators if asthmatic, nebulized recombinant DNAase used as a mucolytic.
Nutritional: high calorie, high protein diet. Creon (pancreatic enzyme) and vitamin supplementation.
Immunisations: usual schedule and pneumococcal/influenza.
Physiotherapy: twice a day for mucous movement
HLT: if lung function deteriorates,
Gene therapy: viral vectors for CFTR gene replacement with normal CF gene. Still research.
What are the complications and prognosis of Cystic fibrosis?
Respiratory: L pneumonia, cronchiectasis, cor pulmonale, PTX, haemoptysis.
GI: cirrhosis, portal HTN, DM, obstruction.
Endocrine: DM, low fertility. Psychological.
Median life 40y, children with pseudomonas have higher mortality over 8y.
