Cystic Fibrosis in Pediatric Age
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Introduction to Cystic Fibrosis
Cystic Fibrosis (CF) is an autosomal recessive genetic disorder affecting multiple organ systems, primarily the respiratory and digestive systems. It is the most common life-limiting genetic condition in Caucasian populations.
Key Epidemiological Points:
- Incidence: approximately 1 in 2,500-3,500 live births in Caucasian populations
- Carrier frequency: 1 in 25 in European populations
- Variable prevalence among different ethnic groups
- Early diagnosis through newborn screening has significantly improved outcomes
Pathophysiology & Genetics
Genetic Basis:
- Mutation in CFTR gene on chromosome 7
- Over 2,000 known mutations categorized into six classes
- Delta F508 mutation is most common (present in ~70% of CF alleles)
- Genotype-phenotype correlations exist but are complex
CFTR Protein Function:
- Chloride channel regulation
- Sodium transport modulation
- Bicarbonate secretion
- Water movement across epithelial surfaces
Organ System Effects:
- Airways: Thick mucus, impaired mucociliary clearance, chronic infection
- Pancreas: Duct obstruction, enzyme insufficiency, inflammation
- Gastrointestinal: Malabsorption, altered gut motility
- Reproductive: Congenital bilateral absence of vas deferens, reduced fertility
- Sweat glands: Elevated chloride concentration
Clinical Manifestations
Respiratory Manifestations:
- Chronic productive cough
- Recurrent respiratory infections
- Bronchiectasis
- Nasal polyps
- Sinusitis
- Digital clubbing
Gastrointestinal Manifestations:
- Meconium ileus (in newborns)
- Failure to thrive
- Steatorrhea
- Rectal prolapse
- Distal intestinal obstruction syndrome (DIOS)
- Pancreatic insufficiency (in 85-90% of patients)
Other System Manifestations:
- Growth delay
- Delayed puberty
- CF-related diabetes (CFRD)
- Osteoporosis
- Heat prostration
- Electrolyte imbalances
Diagnosis & Screening
Newborn Screening:
- Immunoreactive trypsinogen (IRT) testing
- DNA mutation analysis
- Follow-up sweat testing if screening is positive
Diagnostic Criteria:
- Positive newborn screen plus one of the following:
- Sweat chloride ≥60 mmol/L
- Two pathogenic CFTR mutations
- Characteristic clinical features
- Nasal potential difference testing (in uncertain cases)
Initial Evaluation:
- Chest imaging (X-ray and/or CT)
- Respiratory culture
- Pancreatic function tests
- Nutritional assessment
- Genetic counseling
Management Protocol
Respiratory Care:
- Airway clearance techniques:
- Chest physiotherapy
- Oscillating positive expiratory pressure devices
- High-frequency chest wall oscillation
- Inhaled medications:
- Bronchodilators
- Mucolytics (DNase, hypertonic saline)
- Inhaled antibiotics
- CFTR modulators based on genetic mutations
Nutritional Management:
- Pancreatic enzyme replacement therapy
- Fat-soluble vitamin supplementation
- High-calorie, high-protein diet
- Salt supplementation
- Enteral nutrition when needed
Infection Control:
- Regular respiratory cultures
- Prophylactic antibiotics when indicated
- Aggressive treatment of pulmonary exacerbations
- Infection prevention strategies
Complications & Special Considerations
Respiratory Complications:
- Hemoptysis
- Pneumothorax
- Respiratory failure
- Allergic bronchopulmonary aspergillosis (ABPA)
Gastrointestinal Complications:
- Liver disease
- Portal hypertension
- Biliary cirrhosis
- Pancreatitis
Metabolic Complications:
- CF-related diabetes
- Bone disease
- Growth failure
- Salt depletion
Monitoring & Follow-up
Regular Assessments:
- Quarterly clinic visits including:
- Pulmonary function testing
- Growth measurements
- Respiratory culture
- Nutritional assessment
- Annual assessments:
- Comprehensive blood work
- Oral glucose tolerance test (age >10 years)
- Liver function tests
- Bone density scanning
Quality Measures:
- FEV1 trends
- BMI percentiles
- Exacerbation frequency
- Quality of life measures
Prognosis & Quality of Life
Prognostic Factors:
- Genotype
- Age at diagnosis
- Nutritional status
- Pulmonary function
- Infection status
- Access to specialized care
Life Expectancy:
- Median predicted survival now exceeds 40 years
- Continued improvement with new therapies
- Variable based on multiple factors
Further Reading
Clinical Resources:
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Cystic Fibrosis: Objective QnA
- Q: What is the genetic inheritance pattern of cystic fibrosis? A: Autosomal recessive
- Q: Which chromosome contains the CFTR gene mutation responsible for cystic fibrosis? A: Chromosome 7
- Q: What is the most common CFTR mutation in Caucasian populations? A: F508del (deletion of phenylalanine at position 508)
- Q: What is the primary function of the CFTR protein? A: Chloride ion channel regulation
- Q: Which organ systems are primarily affected in cystic fibrosis? A: Respiratory and digestive systems
- Q: What is the characteristic feature of mucus in cystic fibrosis patients? A: Thick and sticky
- Q: What test is considered the gold standard for diagnosing cystic fibrosis? A: Sweat chloride test
- Q: What is the typical chloride concentration in sweat for a positive cystic fibrosis diagnosis? A: ≥60 mmol/L
- Q: Which pancreatic enzymes are commonly deficient in cystic fibrosis patients? A: Lipase, amylase, and protease
- Q: What is the most common respiratory pathogen in cystic fibrosis patients? A: Pseudomonas aeruginosa
- Q: What imaging technique is commonly used to assess lung damage in cystic fibrosis? A: High-resolution computed tomography (HRCT)
- Q: What is bronchiectasis in the context of cystic fibrosis? A: Permanent dilation and destruction of bronchial walls
- Q: Which vitamin deficiencies are common in cystic fibrosis patients? A: Fat-soluble vitamins (A, D, E, K)
- Q: What is the name of the newborn screening test for cystic fibrosis? A: Immunoreactive trypsinogen (IRT) test
- Q: What is the primary goal of physiotherapy in cystic fibrosis management? A: Airway clearance and mucus mobilization
- Q: Which class of antibiotics is commonly used for Pseudomonas aeruginosa infections in cystic fibrosis? A: Inhaled aminoglycosides (e.g., tobramycin)
- Q: What is the role of DNase (dornase alfa) in cystic fibrosis treatment? A: To break down extracellular DNA and reduce mucus viscosity
- Q: Which organ is at risk for cystic fibrosis-related diabetes (CFRD)? A: Pancreas
- Q: What is meconium ileus, and how is it related to cystic fibrosis? A: Intestinal obstruction in newborns due to thick meconium; present in 10-20% of CF cases
- Q: What is the name of the transmembrane conductance regulator potentiator used in some CF patients? A: Ivacaftor
- Q: Which respiratory function test is routinely used to monitor lung function in CF patients? A: Spirometry (FEV1 and FVC)
- Q: What is the main cause of male infertility in cystic fibrosis? A: Congenital bilateral absence of the vas deferens (CBAVD)
- Q: What is the term for the accumulation of salt crystals on the skin in some CF patients? A: Salty skin or salt crystal deposition
- Q: Which gastrointestinal complication is associated with distal intestinal obstruction syndrome (DIOS) in CF? A: Partial or complete bowel obstruction due to thick intestinal contents
- Q: What is the recommended daily salt intake for CF patients compared to healthy individuals? A: 2-4 times higher than normal
- Q: Which growth parameter is often affected in children with cystic fibrosis? A: Height and weight (failure to thrive)
- Q: What is the name of the specialized centers for cystic fibrosis care? A: Cystic Fibrosis Care Centers
- Q: Which respiratory complication can lead to hemoptysis in CF patients? A: Bronchial artery hypertrophy and rupture
- Q: What is the life expectancy for individuals with cystic fibrosis in developed countries as of 2024? A: Mid-40s to early 50s
- Q: What is the role of hypertonic saline in CF treatment? A: To improve mucociliary clearance by increasing airway surface liquid
