Also known as: CF, cystic fibrosis, CFTR, mucoviscidosis
Overview
Autosomal recessive multisystem disorder caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene on chromosome 7, leading to dysfunctional chloride and bicarbonate transport, thick viscous secretions, and progressive damage to lungs, pancreas, intestines, hepatobiliary tract, and reproductive system.
Epidemiology
Most common life-shortening autosomal recessive disease in white populations (~1:2500 live births); ~30,000 affected in the US. Median predicted survival in patients born now exceeds 50 years thanks to CFTR modulators and aggressive care.
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Celiac disease — Failure to thrive, malabsorption with normal sweat chloride; positive tTG IgA, biopsy
Diagnostic workup
Diagnostic criteria
CF Foundation 2017: clinical features OR positive newborn screen OR sibling history PLUS evidence of CFTR dysfunction — sweat chloride ≥60 mmol/L (two tests) OR two disease-causing CFTR mutations OR abnormal nasal potential difference.
Labs
Sweat chloride test (pilocarpine iontophoresis) — diagnostic gold standard: ≥60 mmol/L on two occasions confirms CF; 30-59 intermediate; <30 normal
CFTR gene panel (>2000 mutations identified)
Newborn screening: immunoreactive trypsinogen (IRT) + CFTR mutation panel (now universal in US — diagnosis in infancy in most cases)
Pulmonary exacerbations: IV antibiotics tailored to sputum culture — typically antipseudomonal beta-lactam (cefepime, ceftazidime, piperacillin-tazobactam) + aminoglycoside (tobramycin) for 10-14 days
Chronic azithromycin 250-500 mg 3×/week — anti-inflammatory benefit even without infection
CFRD: insulin (oral hypoglycemics generally inadequate); maintain high-calorie diet
Osteopenia, infertility (especially male CBAVD), nephrolithiasis
Allergic bronchopulmonary aspergillosis (ABPA)
PANCE pearls
Sweat chloride ≥60 mmol/L on two occasions is diagnostic; with newborn screening, most US patients are diagnosed in infancy.
Elexacaftor/tezacaftor/ivacaftor (Trikafta) has dramatically changed CF prognosis — eligible for ~90% of patients with ≥1 F508del or responsive mutation.
Chronic Pseudomonas colonization marks a shift toward inhaled antibiotic suppression therapy (tobramycin or aztreonam cycles).
Burkholderia cepacia complex isolation is often a transplant contraindication and a poor prognostic marker.
CFRD requires insulin (NOT oral agents) and a high-calorie, unrestricted diet — distinct from type 1 or 2 diabetes management.
References
CF Foundation — Cystic Fibrosis Foundation Patient Registry Annual Data Report (2023)
Trikafta Trial — Elexacaftor-Tezacaftor-Ivacaftor for CF with a Single F508del Allele (Middleton et al., NEJM 2019)
CFF Diagnosis — Diagnosis of Cystic Fibrosis: Consensus Guidelines from the Cystic Fibrosis Foundation (Farrell et al., J Pediatr 2017)
CFF Care Guidelines — Cystic Fibrosis Pulmonary Guidelines: Chronic Medications (Mogayzel et al., Am J Respir Crit Care Med 2013)
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