Cystic Fibrosis
Definition
Clinical Features
- autosomal recessive, CFTR gene found on chromosome 7 (t.F508 mutation in 70%, over 800 different mutations identified)
- 1 in 3,000 live births, mostly Caucasians
- mutation in transmembrane conductance regulator of chloride - causes cells to be impermeable to Cl- which increases the reabsorption of Na+
- leads to relative dehydration of airway secretions, resulting in impaired mucociliary transport and airway obstruction
Clinical Features
Investigations
Treatment
Complications
Source
Toronto Notes 2012
- sweat chloride test x 2 (>60 mEq/L)
- false positive tests: malnutrition, coeliac disease, adrenal insufficiency, anorexia nervosa,
- hypothyroidism, nephrogenic diabetes insipidus, nephrotic syndrome
- false negative tests: peripheral edema, cloxacillin, glycogen storage disease,
- hypoparathyroidism, atopic dermatitis, Klinefelter syndrome, hypogammaglobulinemia
Treatment
- nutritional counselling
- high calorie diet
- pancreatic enzyme replacements (Creon)
- fat soluble vitamin supplements
- management of chest disease
- physiotherapy, postural drainage
- exercise
- bronchodilators
- aerosolized DNAase
- antibiotics: depends on sputum C&S (e.g. cephalosporin, cloxacillin, ciprofloxacin, inhaled tobramycin)
- lung transplantation
- genetic counselling
Complications
- respiratory failure
- pneumothorax (poor prognostic sign)
- cor pulmonale (late)
- pancreatic fibrosis with diabetes mellitus
- gallstones
- cirrhosis with portal hypertension
- infertility
- early death (current median survival in Canada is 46.6 yrs)
Source
Toronto Notes 2012