Cystic fibrosis is an autosomal recessive genetic disease caused by variants in the CFTR gene (cystic fibrosis transmembrane conductance regulator). CFTR is a chloride (and bicarbonate) channel on epithelial cells. When it is missing or does not work, less chloride and water move onto epithelial surfaces, so secretions become thick and sticky and block ducts and airways. In sweat glands the defect works in reverse: salt is not reabsorbed, so sweat is very salty.
- The most common variant worldwide is F508del.
- When both parents are carriers, each pregnancy has a 25% chance of an affected child, 50% chance of a carrier, and 25% chance of neither.
- CF was once a childhood disease; with modern care, many clients now live into adulthood, so adult medical-surgical nurses care for CF clients and their complications.
Organs affected
| System | What happens | Result |
|---|
| Lungs | Thick mucus, impaired clearance, chronic infection and neutrophilic inflammation | Chronic productive cough, bronchiectasis, progressive lung damage; respiratory failure is the leading cause of death |
| Pancreas | Ducts blocked → digestive enzymes cannot reach the intestine | Pancreatic insufficiency: fat and protein malabsorption, steatorrhea, poor weight gain, fat-soluble vitamin (A, D, E, K) deficiency; later CF-related diabetes (CFRD) |
| Intestine | Thick intestinal contents | Meconium ileus in newborns; distal intestinal obstruction syndrome (DIOS) in older clients; rectal prolapse |
| Liver / biliary | Bile duct plugging | CF liver disease, gallstones |
| Sweat glands | Salt not reabsorbed | High sweat chloride; risk of salt depletion and dehydration in heat, fever, or exercise |
| Reproductive | Congenital absence of the vas deferens | Infertility in most males; reduced fertility in females |
| Sinuses | Thick secretions | Chronic sinusitis, nasal polyps |
Typical pathogens: Staphylococcus aureus and Haemophilus influenzae early; Pseudomonas aeruginosa becomes common with age and speeds lung decline; Burkholderia cepacia complex and nontuberculous mycobacteria are especially concerning.
Respiratory
- Chronic cough with thick, purulent sputum; wheeze; crackles
- Frequent chest infections; exercise intolerance; dyspnea
- Clubbing, barrel chest in advanced disease
- Hemoptysis; sudden chest pain (pneumothorax)
Gastrointestinal and nutrition
- Steatorrhea — bulky, greasy, foul-smelling stools
- Poor weight gain or weight loss despite a good appetite
- Abdominal distension, cramping, constipation; right lower quadrant mass and vomiting (DIOS)
- Signs of vitamin deficiency: night blindness (A), bone pain or fractures (D), easy bruising (K)
Other
- Parents may report the child "tastes salty" when kissed
- Hyperglycemia or unexplained weight loss (CFRD)
- Dehydration, weakness, muscle cramps in hot weather (salt loss)
- Growth measures: weight, height, BMI percentiles
| Test | Key finding |
|---|
| Newborn screening | Elevated immunoreactive trypsinogen (IRT), usually followed by CFTR variant testing; a positive screen is not a diagnosis |
| Sweat chloride test — confirmatory standard | ≥ 60 mmol/L = consistent with CF; 30–59 mmol/L = intermediate (same cut-offs at all ages, including infants; repeat the test and offer CFTR genetic testing); < 30 mmol/L = CF unlikely |
| CFTR genetic testing | Identifies two disease-causing variants; determines eligibility for CFTR modulators |
| Sputum or throat culture | Every clinic visit; tracks Pseudomonas, MRSA, Burkholderia, NTM |
| Spirometry (FEV₁) | Tracks lung function over time; a drop suggests exacerbation |
| Fecal elastase | Low in pancreatic insufficiency |
| Annual oral glucose tolerance test from about age 10 | Screens for CFRD |
| Liver function tests, fat-soluble vitamin levels, bone density | Monitoring |
Sweat test note: the test uses pilocarpine iontophoresis to stimulate sweating; it is painless. An adequate sample is required — a result is interpreted by the laboratory with the clinical picture.
Care is delivered by a specialized multidisciplinary CF team (physician, nurse, respiratory therapist, dietitian, social worker, pharmacist, psychologist).
CFTR modulators — therapy that targets the basic defect
- Elexacaftor/tezacaftor/ivacaftor for clients with at least one responsive variant (including F508del) from young childhood
- Vanzacaftor/tezacaftor/deutivacaftor, a once-daily combination approved by the FDA in December 2024 for ages 6 years and older
- Ivacaftor alone for certain gating variants
- They improve lung function, weight, and sweat chloride and reduce exacerbations. They are taken with fat-containing food for absorption
Airway clearance (at least twice daily, more during exacerbation)
- Chest physiotherapy with postural drainage and percussion, oscillating positive expiratory pressure devices, high-frequency chest wall oscillation vest, active cycle of breathing, huff coughing, and exercise
Inhaled therapies — typical order
- Bronchodilator (opens airways)
- Hypertonic saline (hydrates mucus)
- Dornase alfa (breaks down DNA in sputum)
- Airway clearance
- Inhaled antibiotic (e.g., tobramycin, aztreonam) last, so it reaches cleared airways
Infection
- Chronic Pseudomonas: inhaled antibiotics, long-term azithromycin
- Pulmonary exacerbation: oral or IV antibiotics (often two antipseudomonal agents) plus intensified airway clearance
Nutrition
- High-calorie, high-protein diet with normal or high fat — do not restrict fat
- Pancreatic enzyme replacement therapy (PERT) with every meal and every snack that contains fat
- Fat-soluble vitamins (A, D, E, K) in CF-specific formulations
- Extra salt, especially in hot weather, with fever, or during exercise; infants often need salt supplements
Advanced disease: lung transplantation.
Drug safety
| Drug | Key safety points |
|---|
| CFTR modulators | Liver injury — check liver function tests before starting, monthly for the first 6 months, every 3 months for the next 12 months, then at least yearly (vanzacaftor combination label; boxed warning for liver injury and failure); cataracts in children — baseline and follow-up eye exams; strong CYP3A inducers (rifampin, rifabutin, carbamazepine, phenytoin, St. John's wort) greatly reduce effect; inhibitors (e.g., ketoconazole, clarithromycin) require dose reduction; avoid grapefruit and Seville oranges |
| Pancreatic enzymes | Take at the start of each meal/snack; swallow capsules whole — do not crush or chew (mouth ulceration, enzyme inactivation); for young children, open capsules and mix the beads with a small amount of acidic soft food (e.g., applesauce), not milk; excessive doses cause fibrosing colonopathy — doses are capped by lipase units per kg |
| Dornase alfa | Voice change, pharyngitis; refrigerate, protect from light; do not mix with other drugs in the nebulizer |
| Hypertonic saline, inhaled antibiotics | Bronchospasm — give the bronchodilator first |
| Aminoglycosides (inhaled or IV tobramycin) | Nephrotoxicity, ototoxicity — monitor creatinine, drug levels (IV), and hearing |
| Azithromycin | QT prolongation, hearing loss; exclude NTM before long-term use |
| Insulin (CFRD) | Hypoglycemia; CFRD is treated with insulin, and calories are not restricted |
Listed in priority order.
- Airway clearance and breathing
- Assess respiratory status, SpO₂, sputum amount and color; give oxygen as ordered
- Carry out airway clearance at least twice daily, before meals or 1–2 hours after (reduces vomiting), in the correct medication sequence
- Stop and report hemoptysis or sudden chest pain (possible pneumothorax)
- Infection prevention
- Keep people with CF at least 6 feet (2 m) apart from one another and wear a mask in health care common areas; do not room CF clients together; contact precautions in hospital per facility policy; clean equipment between uses
- Obtain sputum cultures before antibiotics; administer IV antibiotics on schedule and monitor levels and kidney function
- Nutrition and fluid-electrolyte balance
- Give enzymes immediately before or with meals and snacks; evaluate by stool pattern (fewer, less greasy stools) and weight gain
- High-calorie, high-protein meals and snacks; monitor weight and growth
- Encourage fluids and salt replacement; watch for dehydration and hyponatremia in heat and fever
- Monitor blood glucose (CFRD, steroid use)
- GI monitoring — abdominal distension, pain, vomiting, absent stools (DIOS); ensure adherence to enzymes and fluids
- Activity — encourage regular exercise; it helps clear mucus
- Psychosocial support — chronic illness burden, adolescent-to-adult transition, fertility and family planning, genetic counseling, depression and anxiety screening
- Airway clearance every day, even when feeling well
- Enzymes with every meal and snack (including milk-based snacks and formula); never crush or chew; do not skip enzymes to "save" them
- High-calorie, high-fat, high-protein diet, with CF-specific vitamins
- Add salt and drink extra fluids in hot weather, with exercise, and during fever
- Infection control: hand hygiene; avoid close contact with other people with CF (keep 6 feet apart, including at camps and events); clean and disinfect nebulizers after every use; stay up to date with vaccinations including yearly influenza
- CFTR modulators: take with fat-containing food; keep lab and eye appointments; avoid grapefruit; tell all prescribers and pharmacists about the modulator before starting any new drug or supplement
- Recognize exacerbation signs: more cough or sputum, change in sputum color, blood in sputum, fever, weight loss, reduced energy, fall in lung function — contact the CF team early
- Genetic counseling for family planning; most males are infertile but may be able to have biological children with assisted reproduction; females on modulators may have improved fertility
| Complication | What to watch for |
|---|
| Pulmonary exacerbation → respiratory failure | Increased cough and sputum, dyspnea, falling FEV₁ and SpO₂ |
| Hemoptysis | Blood in sputum; massive bleeding is an airway emergency |
| Pneumothorax | Sudden chest pain, acute dyspnea, absent breath sounds on one side |
| CF-related diabetes | Weight loss, polyuria, polydipsia, declining lung function |
| DIOS | Cramping, distension, vomiting, palpable right lower quadrant mass |
| Salt-depletion dehydration | Lethargy, weakness, cramps, hyponatremia, especially in heat |
| CF liver disease | Jaundice, hepatomegaly, portal hypertension |
| Osteoporosis | Fractures, back pain |
- CF = autosomal recessive CFTR defect → thick secretions; 25% risk per pregnancy when both parents are carriers
- Sweat chloride ≥ 60 mmol/L confirms CF; newborn screening (IRT) only identifies who needs testing
- Classic triad of problems: chronic lung infection, pancreatic insufficiency (steatorrhea, poor weight gain), high salt in sweat
- Enzymes at the start of every meal and snack; swallow whole; adjust by stool and weight
- Diet: high calorie, high protein, normal-to-high fat, fat-soluble vitamins, extra salt
- Airway clearance at least twice daily; bronchodilator first, inhaled antibiotic last
- People with CF must stay at least 6 feet apart — cross-infection risk (Pseudomonas, Burkholderia)
- CFTR modulators: monitor liver tests and eyes; beware CYP3A interactions; take with fatty food
- Most common cause of death: respiratory failure
- Watch for CFRD (annual OGTT from about age 10) and DIOS
- Most males are infertile (absent vas deferens)
Country Notes
United States
- All states include CF in newborn screening; positive screens are referred to accredited CF care centers for sweat testing.
- CFTR modulators are high-cost specialty drugs; nurses often help with insurance and patient-assistance processes.
Philippines
- CF is considered rare in people of Southeast Asian ancestry and may be under-recognized; sweat testing and CFTR genetic testing may have limited availability, so persistent respiratory infections with poor growth and steatorrhea should prompt specialist referral.
- In a hot, humid climate, teach salt and fluid replacement carefully.