Cystic Fibrosis Flashcards
What is the primary cause of cystic fibrosis?
A defect in the gene that codes for the cystic fibrosis trans-membrane conductance regulator
How does the CFTR cholrine channel normally function?
The CFTR channel pumps cholride ions out of epithelial cells
The activation of the channel allows the functioning of surrounding chloride channels
The sodium transporter is inhibited meaning sodium cannot enter cells
This means osmosis will be directed outwards into the airways keeping them moist
How does a CFTR mutation cause cystic fibrosis in the airways?
Cholrine cannot be transported across the cell membrane via the CFR channel or the surrounding cholide channels which canow now not be activated
Inhibition of the sodium ion transporter ceases
Sodium enters the cell reversing the osmotic gradient into the cell
This dries out the aiwards creating very thick sputum
What is the most common mutation in cystic fibrosis?
Deletion of phenylalanine at position 508
What is a promising therapy for cystic fibrosis?
Lumacaftor
How is cystic fibrosis treated if infected with staph aureus?
Oral flucloxacillin
and tigecycline
Oral septrin
How is cystic fibrosis treated if infected with pseudomonas?
- Oral azithromycin
- Nebulised colomycin
- Nebulised or inhaled tobramycin
- Nebulised aztreonam
Cystic fibrosis affects the lungs, but which other parts of the body are affected?
- Pancreas
- Bowels
- Liver
How does cystic fibrosis affect the exocrine function of the pancreas?
Pancreatic ducts are blocked and lipases and amylase cannot be secreted
Digestive failure occurs
How can the exocrine functioning of the liver be treated when cystic fibrosis is present?
CREON
(pancrelipase)
How does cystic fibrosis affect pancreatic endocrine function?
Pancreatic islet cells are destroyed and replaced with fatty tissue
This can cause diabetes and insulin needs to be administered
How can the bowels be affected by cystic fibrosis?
Distal intestinal obstruction syndrome
Mucus blocks the small and large intestines
How is distal intestinal obstruction syndrome (DIOS) treated?
Additional fluids
Gastrografin - a contrast medium to locate areas of blockage
Laxido (laxiative)
How can the liver be affected by cystic fibrosis?
Hepatic ducts become blocked
This can lead to portal hypertension causing variceal bleeding
What is hepatic encephalopathy?
A decrease in brain function due to brain damage by a build up in toxins the liver fails to remove
Why should antibiotics always be used in pairs?
Reduced instance of resistance
What is the best investigation to diagnose cystic fibrosis in adults?
Sweat test
Cystic fibrosis
Question: Neonatal features
Failure to thrive
Meconium Ileus
Rectal prolapse
Cystic fibrosis patients colonised with a which bacterium should avoid cystic fibrosis patients without this bacterium?
Burkholderia cepacia
Cystic fibrosis
Question: Medical Management
Infective exacerbations are treated with:
antibiotics, although for patients with recurrent chest infections prophylactic long-term antibiotics may be prescribed.
Nebulised mucolytics (Dornase Alfa)
Bronchodilators (Inhaled corticosteroids or B2-agonists)
Pancreatic insufficiency is treated with:
Insulin replacement regime
Exocrine enzymatic replacement (Creon)
Vitamin A, D, E, K
Abnormal liver function/ deranged liver function tests are treated with:
Ursodeoxycholic acid
Worsening progressive lung disease is treated with:
Oxygen
Non invasive ventilation
Diuretics if signs of cor pulmonale
What are potential complications of infection with Campylobacter jejuni?
Guillain-Barre Syndrome
Reactive arthritis
Which investigations are indicated in suspected lung cancer?
Sputum cytology
Chest X-ray: Abnormalities that may be seen include nodules, lung collapse, pleural effusion, consolidation, and bony metastases.
Contrast enhanced CT scan: This is used to further confirm the diagnosis and stage (TNM classification) the disease. The CT scan should also include both the adrenals and liver to look for sites of metastases.
Bronchoscopy: Used to obtain a sample for histology
Endobronchial Ultrasound transbronchial needle aspiration (EBUS-TBNA): allows biopsy of lymph nodes, paratracheal and bronchial lung lesions for histology
ystic fibrosis
Question: Investigations in patients with Cystic Fibrosis
Known Cystic Fibrosis
Investigations performed for patients with CF encompass looking for the cause of symptoms, in addition to investigating complications of the condition. They can also be conducted to monitor disease progress and severity.
Bedside Tests:
Sputum culture or throat swab: if a patient presented with symptoms indicative of respiratory tract infection.
Blood: Full Blood Count; Urea and Electrolytes; Liver Function Tests; Clotting studies; Vitamin A, D, E, K and Glucose levels
Glucose tolerance test (to identify diabetes mellitus)
Spirometry: obstructive defect
Aspergillus skin prick test or serology
Radiological Imaging:
Abdominal ultrasound: Distal Intestinal Obstruction; liver cirrhosis; chronic pancreatitis
Chest X-ray: Hyperinflation, bronchiectasis
hat is the cause of Cystic Fibrosis?
A mutation in the cystic fibrosis transmembrane conductance regulator protein (CFTR), a sodium channel that is involved in the production of sweat, gastrointestinal fluids and mucus.
What test do babies have as part of their newborn screening to test for nine serious diseases including cystic fibrosis?
Heel-prick test
Cystic fibrosis
Question: Gastrointestinal features
Pancreatic insufficiency resulting in diabetes mellitus and steatorrhea
Cirrhosis
Portal hypertension
Gallstones
Distal Intestinal Obstruction Syndrome
What is the screening test for cystic fibrosis?
Sweat test
Immunoreactive trypsin levels (effective in neonates <8 weeks old)
Which annual vaccine is recommended for patients with cystic fibrosis?
Influenza
What are the extra pulmonary features of cystic fibrosis?
GI – pancreatic exocrine insufficiency leading to malabsorption of macronutrients and fat soluble vitamins (A, D, E, K). Higher risk of intussusception, constipation and intestinal obstruction. Endocrine – pancreatic endocrine insufficiency leading to diabetics mellitus. Poor uptake of vitamin D leads to dysregulated calcium homeostasis and osteoporosis. Infertility – Most men with cystic fibrosis are infertile due to a congenital absence of the vas deferens. Some women have difficulty reproducing due to thickened cervical mucus and disrupted ovulation due to poor nutrition
Topic: Cystic fibrosis
Question: Respiratory features
Chronic Sinusitis
Nasal Polyps
Symptoms including cough, wheeze, haemoptysis
Recurrent lower respiratory tract infections
Bronchiectasis
Pneumothorax
Cor pulmonale
Respiratory failure
Question 16
What is the most common mutation that causes cystic fibrosis?
The delta F508 mutation that codes for the cystic fibrosis transmembrane conductance regulator (CFTR) protein is most commonly implicated
What is the pattern of inheritance of cystic fibrosis?
Autosomal recessive
Which electrolyte is transported by the transmembrane conductance regulator (CTFR) gene?
Chloride
