Cystic fibrosis Flashcards
1
Q
Most common recessive genetic disorder in white population
A
Cystic fibrosis
2
Q
Pathophysiology
A
- Mutation in CF transmenbrane regulator->chloride channel
- +Chloride excretion, +Na and water reabsorption= thick mucus secretion
- Lung impaired, exocrine pancreas impaired, infertility in men when vas deferens absent, ++salt in sweat, meconium ileus
- 1 in 2500 affected, 1 in 25 carrier
- Most common mutation is delatF508
3
Q
Presentation
A
- 90% are detected at neonatal screening->Day 2-4 test serum trypsinogen->genetic testing, sweat test
- Meconium ileus (10%)
- Malabsorption
- Chronic respiratory infections
- Failure to thrive
- Some may have atypical presentations
4
Q
Common problems and management
A
- Chest infections
Pseudomonas, Bulkholderia cepacia
Bronchodilators
Antibiotics
Steroids
Nebulised DNAse enzymes to break down mucus
- Malabsorption
Fatty foods++, high calories
Pancreatic enzyme replacement
ADEK replacement
Advice from specialist dietician
- Diabetes
25% IGTT
Optimisation of blood glucose
- Salt loss
Salt replacement with careful monitoring
- Liver disease->biliary cirrhosis
Ursodeoxycholic acid
Pseudobowel obstruction
- Subfertility
Absence of vas deferens
Carrier testing in partners
CV/Amniocentesis for antenatal diagnosis recommended
5
Q
Diagnosis
A
- Newborn screening->Immunoreactive serum trypsin levels
- Better prognosis if detected before syptoms
- Gene testing
- Sweat test
6
Q
Prognosis
A
- Significant improvement in treatment over last 25 years, >50% will live >38 years
- Lung function test best measure of disease progressioon
- Heart-lung transplant offered to those with end stage respiratory disease->some survive >15 years beyond their transplant
7
Q
History
A
- May be family history
- FTT w/ ravenous appetite
- Cough and wheeze
- Recurrent chest infections
- Recurrent sinusitis
- Bulky, pale, offensive smelling stools
- Fall in lung function and weight loss may indicate onset of CF-related diabetes
8
Q
Examination
A
- Finger clubbing
- Growth, malnutrition, poor weight gain
- Delayed puberty->tanner staging
- Nasal polyps
- Chest deformity->hyperinflation
- Crackles
- Firm enlarged liver, splenomegaly
- Subcutaneous vascular access
- Gastrotemy tube may be present
9
Q
Features of recurrent respiratory infection
A
- Cough
- Purulent sputum
- Pneumonia
- Chronic pseudomonas
- Bronchiectasis
- Chest deformity
- Eventual respiratory failure
10
Q
Features of poor growth
A
- Requires 40% extra energy intake
- Poor weight gain
- Short stature
- Normal growth acheivbable with pancreatic enzyme replacement and aggressive treatment of chest infections
- Malabsorption
11
Q
Gastrointestinal effects
A
- Pancreatic insufficiency
- Poor fat absorption
- Steatorrhea
- Distended abdomen
- Rectal prolapse
- Distal intestinal obstruction syndrome->can mimic appendicitis
- Need pancreatic enzymes with food
- Diabetes
- Meconium ileus
12
Q
Appearance on chest radiograph
A
- Gross overinflation
- Hilar enlargement
- Ring shadows due to bronchial wall thickening
- Bronchiectatic changes
