CYSTIC FIBROSIS Flashcards

1
Q

What is the carrier rate of cystic fibrosis?

A

1 in 25

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2
Q

What is the incidence of live births with cystic fibrosis?

A

1 in 2500

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3
Q

On what chromosome is the affected cystic fibrosis gene found?

A

Chromosome 7

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4
Q

What is the name of the protein that is affected in cystic fibrosis?

A

Cystic fibrosis transmembrane regulator (CFTR)

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5
Q

What is the result of the mutation of the gene encoding the CFTR protein in cystic fibrosis?

A

Defective c-AMP dependent chloride channel across epithelial cells. This leads to increased viscosity of secretions

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6
Q

Which organs are most affected by cystic fibrosis?

A

Respiratory system - recurrent chest infections

Exocrine pancreas - insufficiency

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7
Q

What is the most useful test for diagnosing cystic fibrosis?

A

Sweat test using pilocarpine iontophoresis to induce sweating and then show abnormal quantities of chloride ions in the sweat.

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8
Q

Infection by which organisms does cystic fibrosis predispose the patient to?

A

S. aureus

H. influenzae

Pseudomonas

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9
Q

What are the long term complications of repeated infections in a cystic fibrosis patient?

A

Bronchiectasis

Abscess formation

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10
Q

What are the features of cystic fibrosis?

A

Chest hyperinflation

Crackles

Wheeze

Finger clubbing

Malabsorption and failure to thrive

Steatorrhea

10-20% present in neonatal period with meconium ileus.

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11
Q

What are the features of meconium ileus?

A

Failure to pass meconium

Bilious vomiting

Distension of the abdomen

Caused by thickened meconium which is secondary to cystic fibrosis

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12
Q

How is cystic fibrosis usually diagnosed?

A

Screening is part of newborn blood spot using immunoreactive trypsinogen (Guthrie test).

Gold standard diagnostic test is the sweat test - failure of the normal reabsorption of sodium and chloride leads to abnormally salty sweat. Two sweat tests showing a chloride of >60 mmol/L confirms CF.

Genetic testing of most common mutations will also help diagnosis.

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13
Q

What are the non-pulmonary aspects of cystic fibrosis?

A

Airway - nasal polyps

GI - Distal ileal obstruction syndrome

Pancreas/endocrine - Diabetes, poor growth, osteoporosis

Reproductive - infertility in males due to absent vas deferens

Joints - arthropathy

Vascular - vasculitis

Hepatic - portal hypertension

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14
Q

How are patients with cystic fibrosis managed with regard to the respiratory system?

A

MDT

Physiotherapy - chest percussion with postural drainage, breathing exercises, positive expiratory pressure masks.

Many centres recommend continuous flucloxacillin therapy in first 2 years of life.

Use of in-dwelling vascular devices (Port-A-Cath) aid regular intravenous antibiotic courses.

Mucolytics such as nebulised hypotonic saline can help mucous clearance

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15
Q

How are patients with cystic fibrosis managed with regard to nutrition?

A

MDT

High calorie diet

Vitamin supplements (especially fat soluble vitamins)

Pancreatic enzyme supplementation using enteric-coated microspheres which contain amylase, lipase and protease.

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16
Q

What is the prognosis of someone diagnosed with cystic fibrosis?

A

50% live beyond 40 but life expectancy remains in the 40s

Lung transplantation can help increase life expectancy