Cystic Fibrosis

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Cystic
disease in Caucasians, 10,600 cases in UK.
Aetiology\: autosomal recessive, mutation on chromosome 7 (CFTR gene, delta-F508); leads to thickened secretions due to
altered chloride and sodium transport.
Risk factor\: family history.
Respiratory e
Gastrointestinal e
DIOS, gallstones.
Other e
Investigations\: urine dip, lung function tests, FBC, CRP, U&Es, LFTs, fasting glucose, vitamin levels, sputum culture, sweat
testing, genetic testing, faecal elastase, chest X-ray, HRCT chest.
Management\: MDT in tertiary centres, vaccinations, chest physiotherapy, antibiotics, inhaled bronchodilators, mucolytics,
pancreatic enzymes, high-calorie diet, PEG/Nasogastric feeding if needed, transplant (lung +/- heart).
Complications\: bronchiectasis, cor pulmonale, haemoptysis, pneumothorax, chronic liver disease, osteoporosis,
psychological e
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A comprehensive topic overview

Introduction

Cystic
which commonly leads to recurrent respiratory infections.
1
CF is the most common inherited disease in Caucasians. In the UK there are around 10,600 cases, whereas worldwide
there are thought to be around 100,000.
2

Aetiology

CF is a genetic disease inherited in an autosomal recessive fashion.
Mutations are found on chromosome 7 in the CF transmembrane conductance regulator (CFTR) gene. The most
common mutation found in Caucasians is delta-F508 (DF508).
1
Normally, the CFTR allows e
lumen, out of the cells.
In CF, more chloride leaves the cell and more sodium is reabsorbed along with water, due to osmosis. Subsequently,
secretions are dehydrated and thickened with increased chloride.
3Risk factors
As CF is an inherited condition, family history of the disease is the only risk factor.
1

Clinical features

CF can present at any age (although it is usually found in newborn screening) and severity of symptoms varies.
1
CF has e
Thickened secretions reduce mucociliary clearance from the bronchi and increased salt concentration leads to impaired
bacterial defences. Subsequently, bacterial colonisation and lung in
lower respiratory tract infections and bronchiectasis.
1
Thickened secretions in sinuses can also lead to recurrent infection and subsequent nasal polyps due to chronic
in
4
The gastrointestinal system is a
endocrine dysfunction.
Impaired exocrine function leads to malabsorption of nutrients and fat-soluble vitamins, whereas impaired endocrine
function results in cystic
pancreatitis. CF causes thickened bile leading to obstruction of the bile ducts and gallstones.
4
Intestinal obstruction in the newborn, termed meconium ileus, can be the presenting feature in infants. 3
Infants can also
1
present with rectal prolapse. Adults can develop distal intestinal obstruction syndrome (DIOS) which presents with
bloating, abdominal pain and vomiting.
4
Infertility is common in boys due to congenital absence or
cervix and irregular menstruation can lead to reduced fertility.
1
Chloride is not resorbed from sweat glands leading to excess salt in the sweat. This allows diagnosis of CF by sweat
testing.
1
The history should focus on respiratory symptoms but should also include questions about the less common features of
History
CF\:
Respiratory\: frequency of infections, cough, sputum (colour, amount), haemoptysis, breathlessness
Pancreatic function\: failure to thrive, steatorrhoea, thirst, polyuria
Gastrointestinal\: abdominal pain, bloating, vomiting
Di
Clinical examination
A thorough respiratory examination should be performed. Typical
General inspection of the environment\: sputum pots, oxygen (concentrator or cylinder with a mask or nasal cannulae),
nebuliser, inhaler
General inspection of the patient\: younger age, increased work of breathing, cachexia, vascular access (Portacath, PICC
line)
Peripheral signs\:
Chest signs\: coarse crackles over areas of bronchiectasis
Examination for other signs of CF should look for\:
Finger prick marks due to insulin use in diabetes
Abdominal examination for pain, signs of chronic liver disease, feeding tubes (NG or PEG)Figure 1. Finger clubbing in bronchiectasis.
5

Di

Common pathologies such as pneumonia, malignancy and pulmonary embolism should be considered depending on
presenting features. If gastrointestinal features are predominant, causes such as coeliac disease should be considered.
A rare but important di
disease caused by dysfunction of cilia in sinuses, lungs and reproductive organs.
4

Investigations

Bedside investigations
Relevant bedside investigations include\:
Urine dip\: for glucose in case of diabetes
Lung function testing\: an obstructive picture is most common but can be restrictive, mixed or normal
Laboratory investigations
Relevant laboratory investigations include\:
1
Blood tests\: FBC and CRP (infection and anaemia), U&Es, fasting glucose, LFTs (biliary or liver e
levels
Sputum culture and sensitivity\: commonly B u r k h o l d e r i a c e p a c i a
Sweat testing\: high chloride concentration in 98% sensitive
Genetic testing\: for CFTR
Faecal elastase\: for pancreatic insu
H a e m o p h i l u s i n
Imaging
Relevant imaging investigations include\:
Chest x-ray\: bronchiectasis, hyperin
High-resolution CT chest\: bronchial wall thickening, bronchiectasis (tree-in-bud appearance, signet ring sign), mucus
plugging (
CT angiography\: in haemoptysis, if endovascular intervention is being consideredFigure 2. Bronchiectasis, complicating left-sided pneumothorax with chest drain,
surgical emphysema, Portacath.
6

Management

CF is usually managed by a multidisciplinary team of specialists in a tertiary centre.
1
Medical management
All patients should have annual vaccinations and lifestyle advice for regular physical exercise.
Respiratory manifestations are managed with\:
Chest physiotherapy for mucus clearance with active cycle of breathing
Prophylactic antibiotics and antibiotics for acute exacerbations guided by sputum culture (oral, inhaled or intravenous)
Inhaled bronchodilators
Mucolytics (oral or inhaled)\: hypertonic saline or dornase alfa
Pancreatic insu
Due to recurrent infection and malabsorption, weight should be closely monitored, and nutrition managed by a dietician.
Supplementation of fat-soluble vitamins and a high-calorie diet is encouraged. If nutrition cannot be maintained, enteral
feeding by PEG or nasogastric tube may be needed.
Fertility counselling should be o
Follow up
Follow up should be carried out with specialists twice a year, in conjunction with primary care. It should include regular
pulmonary function tests, chest x-ray, sputum cultures and diabetes screening.
1
Surgical management
The mainstay of surgical management is transplant (lung +/- heart). Complications such as massive haemoptysis or
pneumothorax may also be managed surgically.

Complications

Respiratory complications are caused by bronchiectasis and recurrent infections. Progressive air
to cor pulmonale and death.
Other respiratory complications include haemoptysis (which can be large volume and life-threatening) and pneumothorax.
Other complications include chronic liver disease (and related sequelae), osteoporosis and psychological eReferences
Patient info. C y s t i c F i b r o s i s . Published in 2020. Available from\: [LINK]
Cystic Fibrosis Trust. C y s t i c LINK]
Radiopaedia. C y s t i c LINK]
National Organization for Rare Disorders. C y s t i c F i b r o s i s . Published in 2017. Available from\: [LINK]
Radiopaedia/Wikipedia. F i n g e r c l u b b i n g i n c y s t i c CC BY NC SA 3.0]
Radiopaedia/Dr Jeremy Jones. B r o n c h i e c t a s i s , c o m p l i c a t i n g l e f t s i d e d p n e u m o t h o r a x w i t h c h e s t d r a i n , e m p h y s e m a , p o r t a c a t h . Licence\: [CC BY NC SA 3.0]
s u r gi c a l

Reviewer

Dr Samantha Cockburn
Respiratory Registrar

Asthma
Bronchiectasis
Chronic Obstructive Pulmonary Disease (COPD)
Croup
Interstitial Lung Disease

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Source\: geekymedics.com