Cystic Fibrosis (CF)

Exam Cram

• Cystic Fibrosis is caused by a delta F508 mutation in the ion channel CFTR gene, causing thick mucuous; inherited in an autosomal recessive inheritance pattern

• Presentation: poor growth, recurrent respiratory infections, finger clubbing

• Diagnosis: sweat test- raised Na+ levels

• Management: MDT, creon, antibiotics (PICC)

Outline

Background

• Autosomal recessive inheritance; CFTR gene, commonest- delta F508 mutation: increased salt excretion leads to mucous becoming thicker and less effective

• Around 2000 mutations noted, 90% will have at least one copy of delta F508 mutation

• Baseline rate of carrier is 1/25, 4%; commonest inherited condition in Caucasian individuals

• Life expectancy improved alot to 65 yrs- depends upon mutation burden & compliance

Complications

• Lungs: Bronchiectasis, Lung Colonisation- Pseudomonas, Staph aureus, Bronchial artery aneurysm, Pneumothorax,

• GI: Pancreatic Insufficiency, Pancreatitis & Diabetes Mellitus (3c), Malnutrition & Sarcopenia, Liver cirrhosis, Gallstones

• Urinary: Urinary Stones

• Reproductive systems: Infertility

Assessment

History

• Poor growth, 

• Recurrent respiratory infections,

• Weight loss

Examination

• Finger clubbing, Nasal polyps

• Bronchiectasis - upper > lower lobes coarse crackles

• Low weight, gastrostomy tube, LT venous access- portocath (can be chest or abdomen)

Investigations

• Screened as part of the Newborn Screening

• Sweat test: high Na+ diagnostic

• Pulmonary function tests

• Deranged LFTs, blood sugar

Diagnosis

Diagnostic criteria: raised Chloride in sweat or genetic testing

Management

Specialist CF MDT

• Respiratory consultant with interest in CF; Geneticist, Transplant surgeons

• PT- chest physio, Dietician- prevent sarcopenia, OT- adaptations, Psychologist, family, social workers

Lifestyle

• Avoiding other CF patients

• Smoking cessation

• High calorie balance diet

Medications

• Disease modifying: Ivacaftor (variable response)

• Oxygen +- NIV, antibiotics- nebulised / PICC, mucolytics, prophylaxis PO azithromycin

• Creon, fat soluble vitamins, insulin, ursodeoxycholic acid, PEG feed 

Surgical

• Bilateral Lung Transplant

• Liver transplant

Med Reg Notes

Curing Cystic Fibrosis

Currently gene therapy is being developed in the USA: a once off injection, that is very expensive. 

Preventing Cystic Fibrosis

Due to it being an autosomal recessive condition, prenatal screening to chose embryos with only heterozygous traits in those with the disease has the ability to greatly reduce the incidence of the cystic fibrosis trait and disease. 

Lung transplant

Indications: home oxygen

Contraindications

• BMI < 15

• Active mycobaceterial infection or Burkholderia colonisation  (not pseudomonas colonisation)

• Persistent non compliance- 5+

Infertility

• 98% CF Men are infertile

• 25% CF Females are infertile

• 15% population baseline infertility rate

Colonisation in CF

• Childhood: staph aureus

• Adulthood: pseudomonas

• Severe resistant organisms: Burkholderia capacia, non tuberculosis myobacterium (abscessus)

Resources and References

1. https://www.nhlbi.nih.gov/health/cystic-fibrosis/diagnosis#:~:text=Newborn%20screening%20for%20cystic%20fibrosis,cause%20your%20baby%20brief%20discomfort.

Produced 2024