Cystic fibrosis

Question 1

CF - background

Answer 1

1. Definition = genetic disease resulting from abnormalities in the cystic fibrosis transmembrane conductance regulator (CFTR) affecting the lungs, intestines, pancreas, liver sweat glands and reproductive organs
2. Most common life-threatening autosomal recessive disorder in Australia
3. 1:2500 births
4. > 1500 known disease-causing mutations that interrupt various stages of CFTR synthesis and function
5. Most common clinical manifestations = pancreatic dysfunction (->calorie malabsorption) and lung disease (-> mucus retention, infection and inflammation)

Question 2

CF - screening (3)

Answer 2

1. All babies screened for CF in Australia; identifies most children with CF
2. Immunoreactive trypsin (IRT) measured in Guthrie blood spot samples. Samples with IRT level above 99th percentile tested for common mutation
3. Dx confirmed by sweat test (pilocarpine iontophoresis) at 6-10 weeks
   - Raised sweat chloride level (>60mmol/L) is diagnostic

Question 3

CF - symptoms

Answer 3

In history, pay attention to:

1. Cough and wheeze
2. SOB (chronic airway infection/bronchiectasis causes progressive obstructive lung disease)
3. Sputum production + haemoptysis (chronic productive cough as bronchiectasis progresses)
4. Stool type (e.g. fatty, oily, pale) and frequency
5. Weight loss or poor weight gain (bc malabsorption)

Note: most children with CF present with:

1. Malabsorption
2. Failure to thrive
3. Recurrent chest infection

(Clubbing is a later sign.)
(Altered properties of the airway epithelium result in abnormally viscid mucus and bacterial colonisation of respiratory tract.)

Question 4

CF - problems at different ages

Answer 4

Infancy (3)

1. Meconium ileus
2. Neonatal jaundice (prolonged)
3. Hypoproteinaemia and oedema (why?)

Childhood (5)

1. Recurrent LRTI
2. Bronchiectasis (occasionally)
3. Poor appetite
4. Rectal prolapse (why?)
5. Nasal polyps

Adolescence (5)

1. Bronchiectasis
2. Diabetes mellitus
3. Cirrhosis and portal hypertension
4. Distal intestinal obstruction
5. Other (4) = pneumothorax, male infertility, arthropathy, psychological problems

Question 5

CF - ix

Answer 5

`1. Sweat test (increased chloride levels >60mmol/L)

2. CXR - hyperinflation, increased AP diameter, bronchial dilatation, cysts, linear shadows, infiltrates
3. Lung function - obstructive pattern with decreased FVC
4. Consider sputum/cough swab
5. Bloods = FBE, UEC, LFTs, BGL

Question 6

CF - mx (1+5+3+5+3)

Answer 6

1. Multidisciplinary team approach. Need paediatric respiratory physician, physiotherapist, dietician, nurse liaison or practitioner in CF, primary care team. Need close cooperation between local hospitals and regional centres.
2. Pulmonary care (5)
   - Physiotherapy at least 2x/d
   - IV abx for recurrent respiratory infections
   - Bronchodilators if reversible airway obstruction
   - Annual influenza immunisation, pneumococcal vaccination
   - Stopping smoking
3. Gastrointestinal management - distal intestinal obstruction/meconium ileus equivalent (3)
   - Lactulose 1mL/kg/d, or
   - Gastrografin = oral dose can be used as single tx dose
   - Oral acetylcysteine solution = prophylaxis
4. Nutrition/other gastro (5 - includes liver)
   - Pancreatic insufficiency treated with oral enteric-coated pancreatic supplements taken with all meals and snacks
   - High calorie diet
   - Salt supplements (salt depletion is a risk in first year of life, and in summer months for older pts)
   - Vitamin supplementation with vitamins A, D, E and K
   - Early identification of liver disease
5. Other issues (3)
   - Psychosocial aspects
   - Lung transplantation
   - Liver transplantation