Cystic Fibrosis (CF)

Cystic Fibrosis (CF)

·        Autosomal recessive.  1 in 25 are carriers

·        Disease of epithelial lined organs: 

o  Lungs: mucus plugging ® chronic inflammation ® necrosis, adjacent pneumonia, bronchiectasis. Leads to chronic infection, emphysema and pseudomonas colonisation. Eventually ® Cor Pulmonale 

o  Pancreas: fibrosis around ducts, dilated ducts, islets cells relatively preserved. ® pancreatic insufficiency 

o  Gut ® meconium ileus, biliary cirrhosis, recurrent RLQ pain

o  Bile ducts obstructed

o  Middle ear 

o  Vas deferens ® infertility

·        Presentation: 

o  Newborn screening (80% will turn out to be carriers, not diseased). Guthrie card for Immuno Reactive Tripsin (IRT). Tripsin leaks into blood from pancreas if pancreatic duct blocked. Sensitivity high (~95%) but not at all specific. If positive then ® gene screen 

o  Neonates: Meconium ileus: 

§  > 90% with meconium ileus will have CF ® obstruction at birth.  Occurs in 15% of those with

§  CF

§  Presentation: bilious vomiting, palpable bowel loops, distension if perforated

§  CXR: distended bowel loops with thickened walls 

§  May also have associated volvulus, small bowel atresia, perforation, neonatal meconium peritonitis secondary to perforation

§  Treatment: enema + IV fluids or surgery

o  Failure to thrive

o  Sibling with CF

·        Pathogenesis: 

o  Abnormality of cAMP dependent chloride transport due to mutation of the CFTR protein. Less water gets out ® thicker mucus Þ obstruction and ¯ciliary clearance 

o  In 70% of the mutations, the protein is not glycosylated normally ® not transported to site

·        Testing:

o  Guthrie screening 

o  Sweat test (lack of Cl channel ® can‟t reabsorb NaCl from isotonic secretions ® salty sweat)

o  Gene screen DF508/U on chromosome 7.

·        Advantages of early diagnosis: ­lung function, ­nutrition, less traumatic diagnostic process

·        Post-natal management:

o  Good nutrition: enzyme replacement, high calories, fat soluble vitamin supplements

o  Antibiotics for URTI

o  Grommets at 2 years

o  Multidisciplinary approach

·        Possible monitoring tests: 

o  CXR, lung function tests, sputum culture (esp pseudomonas lung infection – key prognostic indication)

o  FBC, electrolytes, total protein, albumin, Vit A, D, E, blood glucose

o  Faecal elastase (testing pancreatic insufficiency)

·        Complications include bronchiectasis (CF is commonest cause): bronchi dilated and filled with purulent secretions. Like CF requires regular physio