Cystic Fibrosis

Question 1

What is CF?

Answer 1

Autosomal recessive mutation on chromosome 7, mutation f508 (codes for CFTR protein)

Question 2

When is it mostly diagnosed?

Answer 2

In childhood
90% before 84 y/o

Question 3

RF ?

Answer 3

fHx, caucasian

Question 4

Pathology of CF?

Answer 4

Mutation = defective CFTR gene = normally secretes Cl- (actively) + Na+ (passively) (+H20) into ductal secretions
therefore makes them thin + watery

Now = thicker with increased Na+ and Cl- retention

Question 5

What is the pathology specific to the lung?

Answer 5

Impaired mucociliary clearance as mucus extra thick therefore high stagnation = increased infection risk + difficulty breathing + increased risk if bronchiectasis

Question 6

Sx of CF?

Answer 6

Resp = Thick, sticky sputum cough, recurrent upper resp tract infection, bronchiectasis

Neonates = MECONIUM ILEUS
Meconium (first stool) gets thick + sticky, can get stuck in bowel causing bowel obstruction + failure to thrive

GIT = Thick secretions block pancreatic ducts therefore no pancreatic enzymes released = no fat or protein absorbed = poor weight gain + fail to thrive

Other = Males - atrophy of vas deferens + epididymus (infertility)
Salty sweat

Question 7

Dx of CF?

Answer 7

Sweat test (Na+ and Cl- >60mmol/L in children)

Fecal elastase -ve/ low (normally elastase produces by pancreas + found in faeces; obstruction in CF may mean low/-ve)

fHx, genetic testing (f508)

Question 8

Tx?

Answer 8

Non curative
Conservative = chest physio, no smoking
Drugs = anti mucolytics, bronchodilator, pancreatic enzyme replacements + fat soluble vit supps