Saturday, 30 October 2010

MRCP revision battle 37.6: Cystic fibrosis

CF is an autosomal recessive genetic disorder which results in a mutation of CFTR, leading to Cl not leaving cells and so more Na and water entering, resulting in thick, sticky secreations.

The mutation is on chromosome 7.  70% are ΔF5O8

Incidence = 1/2000.  Carriers = 1/25

Presentation in neonates is failure to thrive, meconim ileus or rectal prolapse.
Later presentation tends to be recurrent respiratory infections, cough, wheeze, bronchiectasis.  85% have steatorrhoea.

Signs include:
-    cyanosis
-    clubbing
-    bilateral course crackles

Diagnosis is by pilocarpine sweat test.  Na/Cl>60mmol/l, usually Cl>Na.  CXR may show bronchietasis.  PCR can pick up 90% of mutations.  Faecal elastase is a good screening tool for exocrine pancreatic dysfunction.  Spirometry shows obstruction.

Treatment is MDT, physio, enzyme replacement, heart/lung transplant.

Complications include  
  • diabetes (1/3) 
  • gallstones
  • cirrhosis
  • OP
  • male infertility (no vas deferens or epididimus)
  • vasculitis
  • nasal polyps (1/3) 
  • HPOA (if you don't know what this is you will by the end of the next battle)
  • infections
    • s.aureus
    • h.influenzae
    • pseudomonas
    • s.pneumoniae
    • burkholderia cepacia (gram negative)
    • aspergillos

It tends to be the upper lobes of the lungs that are damaged.

Mean age of death ~30.

So to the final battle of the day, HPOA...