Cystic Fibrosis

Question 1

The abnormality in CF

Answer 1

Autosomal recessive
Cystic Fibrosis Transmembrane Regulator (CFTR) protein
Most commonly deltaF508
Defective chloride ion transport leading to increased viscosity of secretions
Lungs and exocrine pancreas most severely affected

Question 2

Antenatal presentation

Answer 2

Amniocentesis/chorionic villus sampling

Ultrasound demonstration of bowel perforation/hyperechogenic bowel (4% cases due to cystic fibrosis (CF))

Question 3

Perinatal presentation

Answer 3

Screening
Meconium ileus (1 in 10 presentations)
Obstructive jaundice (rare)

Question 4

Classical clinical presentation

Answer 4

Recurrent LRTI

Failure to thrive

Question 5

Other presentations

Answer 5

Nasal polyps
Sinusitis
Heat exhaustion
Pancreatitis
Diarrhoea
Rectal prolapse

Question 6

Complications

Answer 6

Pulmonary: Recurrent or chronic chest infections (pseudomonas, staph. aureus, haemophilus influenzae); chest deformity
Hepatic: portal hypertension; biliary stasis; liver cirrhosis
Pancreas/endocrine: diabetes; poor growth/development; osteoporosis
GI: rectal prolapse; distal intestinal obstruction syndrome (mimics appendicitis) (DIOS)
Reproductive: male infertility (absence of vas deferens)
MSK: Arthropathy
Vascular: Vasculitis
Other: Salt-losing crisis

Question 7

Chest radiograph

Answer 7

Hyperinflated

Broncial wall thickening and bronchiectatic change (hilar enlargement and ring shadows)

Question 8

Key history points

Answer 8

Family history (most new diagnoses do not have FH)
Failure to thrive with ravenous appetite
Cough and wheeze - thick, purulent sputum
Recurrent chest infection
Recurrent sinusitis
Bulky, pale, offensive smelling stool, often difficult to flush
Fall in lung function and weight loss may indicate onset of diabetes

Question 9

Examination

Answer 9

Hyperinflation
Clubbing
Wheeze
Crackles
Evidence of malnutrition
Delayed puberty
Nasal polyps
Chest deformity
Firm enlarged liver (rare) and splenomegaly
subcut vascular access devices and gastrostomy tube
Obstructive picture on spirometry

Question 10

Diagnosis

Answer 10

Bloodspot test
Mutation analysis of CFTR gene (only includes 30 of 1200 mutations)
Sweat test: diagnostic; pass electric current across skin; two of >60mmol/L chloride confirm (normal <15)

Question 11

Management

Answer 11

Mainly focussed on respiratory management and nutritional support
Resp: physio; antibiotics; nebulized mucolytics; bronchodilators; good blood glucose control
Nutritional support: high calorie diet with vit supplementation; pancreatic enzyme supplementation; salt supplementation
Fertility treatment

Question 12

Prognosis

Answer 12

Half live past 40
Lung transplant: 90% 1 year; 50% 5 years; up to 15 years
Lung function best measure of disease progession

Question 13

Cystic fibrosis (CF) is a multi-organ disease best managed in a multidisciplinary setting in conjunction with a specialist centre for CF, with treatment tailored to the individual.

Answer 13

Just that

Question 14

Investigations

Answer 14

Sweat testing
Genetic testing
Sinus X-ray or CT scan - opacification of the sinuses
CXR or CT of thorax
Lung function testing (spirometry unreliable before 6y)Sputum microbiology - common pathogens include Haemophilus influenzae, Staphylococcus aureus, Pseudomonas aeruginosa, Burkholderia cepacia, Escherichia coli, and Klebsiella pneumoniae
Various blood tests including FBC, U&Es, fasting glucose, LFTs, and vitamin A, D and E levels are usually performed
Semen analysis if appropriate