Cystic fibrosis

Question 1

Cystic fibrosis

Answer 1

Autosomal recessive

Increased viscosity of secretions (lungs and pancreas)

Defect in cystic fibrosis transmembrane conductance regulator gene

Question 2

Organisms which may colonise CF patients

Answer 2

Staphylococcus aureus

Pseudomonas aeeruginosa

Burkholderia cepacia

Aspergillus

Question 3

Presenting features

Answer 3

Neonatal: meconium ileus, less commonly prolonged jaundice

Recurrent chest infections

Malabsorption: steatorrhoea, failure to thrive

Liver disease

Question 4

Other features

Answer 4

Short stature

Diabetes mellitus

Delayed. puberty

Rectal prolapse (due to bulky stools)

Nasal polyps

Male infertility, female subfertility

Question 5

Sweat test

Answer 5

Patients with CF have abnormally high sweat chloride

Question 6

Causes of false positive sweat test

Answer 6

Malnutrition

Adrenal insufficiency

Glycogen storage disease

Nephrogenic diabetes insipidus

Hypothyroidism

Hypoparathyroidism

G6PD

Ectodermal dysplasia

Skin oedema due to hypoalbuminaemia/ hypoproteinaemia

Question 7

Management

Answer 7

Regular chest physiotherapy

High calorie high fat diet

Minimise contact with other CF patients

Vitamin supplementation

Pancreatic enzyme supplementation with meals

Lung transplant

Question 8

Lumacaftor/Ivacaftor

Answer 8

For patients homozygous for delta F508 mutation

Increases number of CFTR proteins that are transported to cell surface