Cystic fibrosis

Question 1

What is cystic fibrosis?

Answer 1

autosomal recessive disorder caused by a mutation in the CFTR gene leading to the production of defective chloride channels in cell membranes of the exocrine glands

Question 2

What are the clinical features of cystic fibrosis?

Answer 2

Meconium ileus
Failure to thrive
GI symptoms

Pancreatic disease (i.e. Pancreatitis, Exocrine pancreatic insufficiency) 
Liver and bile duct abnormalities
Intestinal obstruction 
Chronic productive cough 
salty-tasting sweat 
kidney stones
recurrent UTIs 
infertility

Question 3

How is cystic fibrosis diagnosed?

Answer 3

(Sweat chloride test) Normal: < 40 mEq/l, Cystic fibrosis: > 60 mEq/l
(CFTR gene mutation test)

Question 4

What are the screening methods for cystic fibrosis?

Answer 4

(Newborn screening) ↑ Immunoreactive trypsinogen (IRT) in CF via heel-prick test

Question 5

What are the causative organisms in cystic fibrosis exacerbation?

Answer 5

(Children) Staphylococcus aureus most common

(Adult) Pseudomonas aeruginosa most common

Question 6

What is the treatment for cystic fibrosis?

Answer 6

(Lifestyle changes) regular chest physiotherapy and postural drainage
high calorie diet, including high fat intake
minimise contact with other CF patients
vitamin supplementation
pancreatic enzyme supplements
(Medication) Lumacaftor/Ivacaftor
(lumacaftor increases the number of CFTR proteins that are transported to the cell surface
ivacaftor is a potentiator of CFTR that is already at the cell surface, increasing the probability that the defective channel will be open)