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What are the regulatory functions of the cystic fibrosis transmembrane conductance regulator (CFTR)?
- 1. ion transport (chloride, bicarbonate, sodium)
- 2. pulmonary inflammation
- 3. bacterial adherence
- 4. mucus rheology
What secondary messerger is the CFTR affected by?
CFTR allows ions to follow what type of gradient?
What occurs in a Class I CFTR defect?
protein not synthesized
What occurs in a Class II CFTR defect?
- 1. immature CFTR synthesized
- 2. most common mutation - ΔF508
What occurs in a Class III CFTR defect?
- 1. CFTR synthesized and placed in membrane
- 2. secondary messenger activation and regulation dysfunctional
- 3. most common mutation - G551D
What occurs in a Class IV CFTR defect?
- 1. CFTR synthesized and placed in membrane2. chloride ion flow reduced
What occurs in a Class V CFTR defect?
CFTR synthesis and processing is partially defective
What occurs in a Class VI CFTR defect?
- 1. CFTR synthesized and place in membrane
- 2. other ion flow reduced
What evidence of CFTR dysfunction is required for CF diagnosis?
- 1. Two or more mutations in CFTR
- 2. Two or more sweat chloride tests over 60 mmol/L
- 3. Abnormal nasal potential difference
How is prenatal testing done for CF diagnosis?
- 1. parents carry CF trait
- 2. echogenic bowel detected on fetal ultrasound
In which states are newborns screened for CF and which mutations are screened?
- Screened in all 50 states
- Screened for the 23 most common mutations
What is the sweat chloride test for CF diagnosis?
pilocarpine induced sweating
What defines an abnormal result in the sweat chloride test (mmol/L)?
Abnormal = >60 mmol/L
What defines an intermediate result of the sweat chloride test (mmol/L)?
- < 6 months of age: 30-59 mmol/L
- > 6 months of age: 40-59 mmol/L
What is a normal value of the sweat chloride test for CF diagnosis?
- < 6 months of age: < 30 mmol/L
- > 6 months of age: < 40 mmol/L
What is the next step of CF diagnosis after a sweat choride test returns with intermediate results?
What does > 2 CFTR mutations indicate?
confirmed CF diagnosis
What does < 1 CFTR mutation indicate in the sweat test?
What must occur if a questionable CF diagnosis occurs?
- 1. repeat sweat test or
- 2. expand DNA testing
What occurs if a repeat sweat test is > 60 mmol/L?
What occurs if a repeat sweat test is < 60 mmol/L?
- > 60 mmol/L: confirmed CF
- < 60 mmol/L: follow clinically
What occurs if an expanded DNA test reveals > 2 CFTR or < 1 CFTR mutation?
- > 2 CFTR mutations: confirmed CF
- < 1 CFTR mutation: follow clinically
What is the gastrointestinal presentation of CF?
- 1. meconium ileus
- 2. failure to thrive
- 3. steatorrhea
- 4. edema
- 5. hypoproteinemia
- 6. anemia
- 7. electrolyte variability
What are the pancreatic manifestations of CF?
- 1. pancreatic insufficiency
- 2. CF-related diabetes
How many patients will experience pancreatic insufficiency?
What happens to pancreatic function with age?
Pancreated functions decrease with age
Which classes of CF are correlated with genotype?
When does duct obstruction begin as a pancreatic insufficiency in CF?
May begin in 2nd trimester
What level of the fecal elastase testing indicates insufficiency?
Less than 200 mcg/gram
What are the general principles associated with pancreatic enzyme replacement therapy (PERT)?
- 1. enzymes: lipase, protease, amylase
- 2. dosed based on lipase units per weight or fat intake
- 3. coating dissolves in alkaline environments
What is the weight-based dosing of PERT?
- < 4yo: 1000 units of lipase per kg per meal
- > 4yo: 500 units of lipase per kg per meal
- maximum of 2500 units of lipase per kg per meal
- doses given with fatty snacks
What is the fat-based dosing for PERT?
- 1. 2000 units of lipase per 120mL of feedings
- 2. maximum of 2500 units of lipase per kg per feeding
- 3. maximum daily dose of 10,000 unis of lipase per kig
What vitamin replacement is necessary for PERT?
- Start with diagnosis
- Fat-soluble vitamin replacement:
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K
What are the risk factors for CF-related diabetes?
- advanced age
- pancreatic insufficiency ΔF508 mutation
What are the intestinal manifestations of CF?
- 1. GERD
- 2. Meconium ileus
- 3. Distal intestinal obstruction syndrome (DIOS)
- 4. Constipation
- 5. Intussusception
- 6. Small bowel bacterial overgrowth
- 7. Rectal prolapse
Discuss the pertinant information associated with GERD and CF.
- 6-8 times more prevalent in CF patients
- Reflux episodes higher than control populations
- Esophageal acid exposure higher than controls
- -decreased LES tone
- -increased intra-abdominal pressure
- -hyperinflated lungs
- -chest physiotherapy
What are the available treatments for GERD associated with CF?
- 1. Chest physiotherapy
- 2. Proton Pump Inhibitors
When should chest physiotherapy for GERD be administered?
perform prior to meals
What is the dosing of PPI's for the treatment of GERD?
- 0.2 - 2 mg/kg/day
- 1-2 times daily
How often does meconium ileus occur in CF patients?
10% of CF presentations
What are the 2 types of classification of meconium ileus?
- 1. simple
- 2. complex (40%)
What are some common problems associated with complex meconium ileus?
- 1. perforation
- 2. atresia
- 3. meconium peritonitis
How is meconium ileus diagnosed?
confirmed with contrast enema
What is DIOS?
- 1. common if patient has histor of meconium ileus
- 2. no relationships with mutations
- 3. acute blockage of the ileum
How are complete acute blockages of the ileum (DIOS) cleared?
1. Surgery (complete)
How are partial acute blockages of the ileum (DIOS) cleared?
- 1. Rehydration
- 2. Osmotic laxatives (polyethylene glycol, gastrografin, electrolye solution)
What are the GI classifications of CF?
- 1. pancreatic manifestations
- 2. intestinal manifestations
- 3. hepatobiliary
What hepatobiliary complications are associated with CF?
- 1. biliary cirrhosis
- 2. liver disease
- 3. neonatal cholestasis
What disease does biliary cirrhosis lead to and how is it treated?
- Leads to liver disease
- Treatment: Ursodiol 30 mg/kg/day divided twice daily
How is liver disease recognized?
slight elevations in alkaline phosphatase
How is neonatal cholestasis recognized?
- 1. history of meconium ileus
- 2. prolonged parenteral nutrition
- 3. increased risk of liver ccirrhosis
- 4. treatment: ursodiol 30 mg/kg/day divided 2-3 times daily
What are the pulmonary presentations of CF?
- 1. recurrent cough
- 2. persistent cough
- 3. prolonged wheezing
- 4. recurrent bronchiolitis
- 5. produtive cough
Discuss reactive airway disease.
- 1. Directly related to lunch disease severity
- 2. Treatment: bronchodilators
- 3. worsening lunch disease: reduction in smooth muscle support system; collapsing muscle worsens obstruction
Discuss Chronic pulmonary issues associated with CF.
- 1. Chronic airway obstruction
- 2. Bacterial colonization of clogged airways
- 3. Chronic medictions
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