cystic fibrosis Flashcards
inheritance
AR disorder involving mutation of CFTR gene
Located on long arm of chromosome 7
The most common mutation is a 3-base pair deletion that leads to the loss of a single phenylalanine at position 508
Pathophysiology
Defective CFTR results in decreased secretion of chloride and increased reabsorption of sodium and water across epithelial cells.
The resultant reduced height of epithelial lining fluid and decreased hydration of mucus results in mucus that is stickier to bacteria, which promotes infection and inflammation.
The tissues most affected
lungs, pancreas, intestinal mucosa, glands, reproductive tracts, and sweat gland
GIT problems
Chronic diarrhea and steatorrhea Malabsorption FTT DIOS Rectal prolapse Intussception GE reflux
Meconium ilius
Intestinal obstruction
Delayed passage of
meconium
Prolonged Jaundice
Pancreas and liver clinical
Pancreatic insufficiency in 85%, and 50% presents at birth
Cholelithiasis
Focal biliary cirrhosis
Pancreatic tissue damage leads to diabetes mellitus in 8-12% of CF patients older than 25 years (CFDM)
Lung Disease
early thickening of airway mucus
2- colonization with pathogenic bacteria
3- the presence of diffuse airway inflammation
4- destruction of the conducting airways and surrounding lung parenchyma
Airway colonization
Staph aureus
Pseudomonus aragenosa
Hemophilus influenza
Others:
Burkholdera capacia
worsening lung function
poor overall outcome
Respiratory system manifestations
Cough Recurrent wheezing Recurrent pneumonia Atypical asthma Dyspnea on exertion Hemoptysis Chest pain Tachypnea Respiratory distress with retractions Wheeze or crackles Increased anteroposterior diameter of chest Clubbing Recurrent pneumonia
Bronchiolitis, bronchitis, then brochiactasis
Pulmonary hypertension, cor-pulmonale
Chronic sinusitis
Polyps in 25% of CF patients
sweat gland involvement will lead to
Sweat with high salt content
Dehydration with hyponatremia
Hypochloremic metabolic alkalosis
Reproductive tract involvement will lead to
Delayed puberty
Male: atresia of vas deferens, sterility, undescended testicles and hydrocele
Female: thick cervival mucus, and decreased fertility, ammenhorea
Diagnosis
Sweat chloride more than 60 twice (or once with positive genetic testing), plus one of theses:
Chronic respiratory system obstructive involvement
Pancreatic insufficiency
CF in siblings
+genatic test
Stimulation of the sweat gland with
pilocarpine
False positive test
Untreated adrenal insufficiency Glycogen storage disease Type I fucosidosis Hypothyroidism Vasopressin-resistant diabetes insipidus Ectodermal dysplasia Malnutrition Mucopolysaccharidosis Panhypopituitarism Familial cholestasis Familial hypoparathyroidism Atopic dermatitis
PFT result
Obstructive changes:
Decreased FEF25-75
Decreased FEV1/FVC
Decreased expiratory flow
Increased residual volume
test For pancreatic insufficiency
For children who are pancreatic sufficient: Obtain fecal elastase yearly, especially if mutations are associated with pancreatic insufficiency
