Cystic Fibrosis Flashcards
Which blood test is raised in CF?
Immunoreactive trypsinogen
Define cystic fibrosis
A progressive, genetic disease that causes persistent lung infections and limits the ability to breathe over time
An autosomal recessive disorder causing increased viscosity of secretions (e.g. lungs and pancreas)
What is the inheritance of CF
Autosomal recessive
If both parents have the faulty gene, what are the chances of their children having CF?
1/4 chance the child with have CF
1/2 chance the child will not have CF but will carry the faulty gene
1/4 chance the child will not have CF and will not carry the faulty gene
If both parents are healthy, one sibling has cystic fibrosis and a second child does not have the disease, what is the likelihood of the second child being a carrier?
2 in 3
Presentation of CF in neonates
May present acutely with meconium ileus
Viscous meconium (from thick mucus) causes a delay in passing meconium and even gastrointestinal obstruction
Meconium ileus is diagnosed and treated with a gastrograffin enema
Presentation of CF in infants
Parents commenting that baby’s sweat is very salty
Presentation of CF in toddlers
Poor weight gain and steatorrhoea
Reduced pancreatic lipase enzyme secretion inhibits fat absorption, causing steatorrhoea
This poor fat absorption also contributes to deficiency of fat-soluble vitamins (A, D, E and K)
Presentation of CF in older children
Delayed onset puberty
Recurrent chest infections (40%)
Liver disease
Symptoms of cystic fibrosis
Chronic cough
Thick sputum production
Recurrent respiratory tract infections
Loose, greasy stools (steatorrhoea) due to a lack of fat digesting lipase enzymes
Abdominal pain and bloating
Parents may report the child tastes particularlysaltywhen they kiss them, due to the concentrated salt in the sweat
Poor weight and height gain (failure to thrive)
Signs of cystic fibrosis
Low weight or height on growth charts
Nasal polyps
Finger clubbing
Crackles and wheezes on auscultation
Abdominal distention
Pathophysiology of cystic fibrosis
Defect in the cystic fibrosis transmembrane conductance regulator gene (CFTR), which codes a cAMP-regulated chloride channel
In the UK 80% of CF cases are due to delta F508 on the long arm of chromosome 7
Investigations in cystic fibrosis
Newborn blood spot testingis performed on all children shortly after birth
Thesweat testis thegold standardfor diagnosis
Genetic testingforCFTR genecan be performed during pregnancy byamniocentesisorchorionic villous sampling, or as a blood test after birth
Common false positives in sweat test
Malnutrition
Adrenal insufficiency
Glycogen storage diseases
Nephrogenic diabetes insipidus
Hypothyroidism, hypoparathyroidism
G6PD
Ectodermal dysplasia
Management of cystic fibrosis
Chest physio several times a day to clear mucus, reduce risk of infection/colonisation
Exercise to improve respiratory function and reserve, clear sputum
High calorie diet for malabsorption, inc. respiratory effort etc.
CREON tablets to digest fats in those with pancreatic insufficiency (replace missing lipase enzymes)
Prophylactic flucloxacillin to reduce risk of bacterial infection (esp. Staph. aureus)
