Cystic Fibrosis

Question 1

What is the cause of CF?

Answer 1

Autosomal recessive disease leading to mutations in the CFTR gene on chromosome 7.
Most common mutation is a deletion of the phenylalanine at position 508.

Question 2

What is the pathophysiology of CF?

Answer 2

1. The CFTR gene transports Cl- ions out of cells into airways, also enabling the movement of water.
2. The defective ion transport through CFTR means airway surface liquid hydration is reduced.
3. This leads to thick and sticky mucus, and impaired mucociliary clearance
4. There is also increased sodium absorption across airway epithelium

Question 3

What are the clinical features of CF in a neonate?

Answer 3

Failure to thrive, meconium ileus, rectal prolapse

Question 4

What are the respiratory clinical features of CF in children/young adults?

Answer 4

Cough, wheeze, recurrent infections, bronchiectasis, pneumothorax, haemoptysis, respiratory failure, cor pulmonale

Question 5

What are the GI clinical features of CF in children/young adults?

Answer 5

Pancreatic insufficiency - DM, steatorrhoea
Distal intestinal obstruction syndome - eg meconium ileus equivalent
Gallstones
Cirrhosis

Question 6

What are some other body system features of CF in children/young adults?

Answer 6

• Male infertility
• Osteoporosis, arthritis, hypertrophic pulmonary osteoarthropathy
• Vasculitis
• Nasal polyps, sinusitis

Question 7

What are some signs you’d see on examination if a patient had CF?

Answer 7

Finger clubbing
Cyanosis
Bilateral coarse crackles

Question 8

How is CF diagnosed?

Answer 8

1. Sweat test - NaCl>60mmol/L, chloride usually greater than sodium
2. Genetic testing - For common CF mutations. Faecal elastase can be used to screen for exocrine pancreatic dysfunction

Question 9

What other testing can you do with a CF patient?

Answer 9

1. Bloods - FBC, U+E, LFT, clotting, vitamin A,D,E, annual glucose tolerance testing
2. Bacteriology - Cough swab, sputum culture
3. Radiology - CXR, hyperinflation, bronchiectasis
4. Abdo ultrasound - Fatty liver, cirrhosis, chronic pancreatitis

Question 10

What is the pulmonary management for a CF patient?

Answer 10

• Physiotherapy
• Antibiotics for acute infective exacerbations/prophylactically
• Mucolytics
• Bronchodilators
• Annual CXR surveillance

Question 11

What is the GI management for a CF patient?

Answer 11

• Pancreatic enzyme replacement
• Fat soluble vitamin supplements (ADEK)
• Ursodeoxycholic acid for impaired liver function
• Cirrhosis may require liver transplantation
• High calorie intake

Question 12

What are some other managements for a CF patient?

Answer 12

• Treatment for CF related diabetes (annual OGTT from 12yo)
• DEXA bone scan for OA and treatment
• Arthritis, sinusitis, vasculitis management
• Fertility and genetic councilling

Question 13

What is the prognosis for CF?

Answer 13

Median survival is 41 years but a baby born today would expect to live longer

Question 14

What should CF patients avoid?

Answer 14

Pseudomonas - Jacuzzis, other CF patients

Aspergillus - Stables, compost, rotting vegetation

Question 15

What are some new CF drugs?

Answer 15

Lumacaftor - CTFR chaperone during protein folding, increases number of proteins that reach cell surface. Suitable for patients with Phe508del
Ivacaftor - Improves Cl- transport through the ion channel