Cystic Fibrosis Flashcards
What is cystic fibrosis?
An autosomal recessive condition that leads to abnormally viscous mucous blockages of many tubular structures including conducting airways and lungs
What is the median survival for cystic fibrosis?
41 years
What causes cystic fibrosis?
Mutation in the CFTR channel, which carries Cl
This leads to less Cl and more Na and H2O, causing thick, sticky secretions
Which chromosome will contain the mutation for cystic fibrosis?
Chromosome 7
What are the two possible mutations that can cause cystic fibrosis?
G551D
F508del
What is the best diagnostic indicator for cystic fibrosis?
The sweat test
What are some organs that cystic fibrosis affects?
Sweat glands Lungs Reproductive organs Pancreas Intestines
What result in the sweat test indicates a referral to a CF centre as it is likely CF?
> 60 mmol/L
What are the symptoms of cystic fibrosis affecting the lungs?
Wet-sounding cough Recurrent infections Chronic sinusitis Bronchiectasis Nasal polyps
What can cystic fibrosis cause in the reproductive organs?
Bilateral absence of the vas deferens
What are the symptoms of cystic fibrosis affecting the pancreas?
Failure to thrive and poor weight gain with voracious appetite in kids
Exocrine - steatorrhoea
Endocrine - diabetes mellitus
Gallbladder stones, liver cirrhsis
What are the symptoms of cystic fibrosis affecting the intestines?
Failure to pass meconium (meconium ileus)
Digital intestinal obstruction syndrome in young adults
What are signs of cystic fibrosis?
Cyanosis Finger clubbing Bilateral coarse crackles Appearance of malnutrition or low BMI Nasal polyps Bilateral absence of the vas deferens in males
What is used for screening newborns?
Dried heel prick test
How does the dried heel prick test work?
Quantifies serum immunoreactive trypsinogen (IRT)
What is done if the skin heel prick test is positive?
Confirmatory sweat test and genetic testing
Refer to CF centre
(Not diagnostic)
What is the usual name for the ‘pilocarpine iontophoresis’ test?
Sweat test
What are the advantages of the sweat test?
Painless
Relatively inexpensive
Provides results within a few hours
Accutare
What does a negative sweat test mean?
Cl <30 mmol/L - CF unlikely but if in doubt refer to CF centre
What does a positive sweat test mean?
Cl >60 mmol/L - CF very likely, refer to CF centre
What does a sweat test in the indeterminate range mean?
Further investigation and genetic testing may be required
What is the genetic testing for cystic fibrosis?
The most common CFTR mutations are screened for and 2 positive CFTR mutations are found
What further investigation can be done for cystic fibrosis?
Sinus x-ray
Deep throat swab
What is the management for cystic fibrosis with a G551D mutation?
Ivacaftor
What is the management for cystic fibrosis with a F508del mutation?
Lumacaftor
What is the respiratory management for cystic fibrosis?
Prophylactic antibiotics Physiotherapy Bronchodilators Mucolytics (Dnase) Annual CXR
What antibiotics are used for an exacerbation of pseudomonas, staph aureus and cepacia?
Pseudomonas - ceftazidime
Staph aureus - flucloxacillin
Cepacia - temocillin
What is the GI management for cystic fibrosis?
In exocrine pancreatic insufficiency - CREON
In endocrine pancreatic failure - insulin
