Lesson
CFTR Biology, Genotype, and Diagnosis
Cystic fibrosis requires a compatible clinical context and objective evidence of CFTR dysfunction. Genotype helps explain mechanism and treatment eligibility but does not replace phenotype.
- CFTR channel function
- Mutation classes and protein fate
- Newborn screening
- Sweat chloride
- Genotype and functional testing
Reduced CFTR changes salt, water, pH, and secretion
Impaired clearance creates obstruction and infection
Airway, pancreas, intestine, liver, sweat, and reproduction
Trace the ion and water defect
CFTR is an epithelial anion channel and regulator that conducts chloride and bicarbonate. Reduced function dehydrates airway surface liquid, impairs mucociliary clearance, acidifies secretions, and changes sodium and water movement. The same defect contributes to pancreatic duct obstruction, intestinal disease, concentrated sweat, hepatobiliary disease, and reproductive tract abnormalities.
Connect mutation to protein behavior
Variants can reduce synthesis, processing, channel gating, conductance, quantity, or stability. F508del produces a major folding and trafficking defect plus reduced surface stability. Correctors improve folding and delivery of selected mutant protein, while potentiators increase channel opening at the cell surface. A functional classification helps explain pharmacology, but eligibility follows current product-specific responsive-variant labeling.
Use screening to begin, not end, diagnosis
Newborn immunoreactive trypsinogen screening identifies risk, not the final diagnosis. Confirm through a certified sweat test, CFTR genetic analysis, clinical evaluation, and additional functional testing when needed. Symptoms can include recurrent sinopulmonary disease, bronchiectasis, meconium ileus, malabsorption, pancreatitis, salt-loss syndromes, infertility, or a family history.
Interpret sweat chloride in context
Sweat chloride at least 60 mmol per L supports CF in the appropriate setting. Values from 30 through 59 require repeat testing and extended evaluation. A result below 30 makes CF less likely but does not absolutely exclude it when genotype or phenotype remains compelling. Quantity-not-sufficient samples require recollection, not estimation.
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Lesson
Airway Clearance and Chronic Pulmonary Therapy
Airway care combines physical clearance, hydration of secretions, mucus degradation, exercise, inhaled delivery, equipment hygiene, and a sequence the patient can sustain.
- Individualized airway clearance
- Bronchodilator role
- Hypertonic saline
- Dornase alfa
- Treatment order and equipment
Reduce treatment-related bronchospasm when indicated
Hydrate secretions and move them toward cough
Reduce viscosity and deliver suppression after clearance
Make airway clearance individualized and active
Positive expiratory pressure, oscillatory PEP, chest-wall oscillation, active-cycle breathing, autogenic drainage, percussion, and other methods mobilize secretions. No single method is universally superior. Technique, age, preference, sputum burden, lung function, adherence, and response determine the best plan. Aerobic exercise complements but does not automatically replace prescribed clearance.
Hydrate and depolymerize secretions
Inhaled hypertonic saline increases airway surface hydration and can provoke bronchospasm, cough, or salt taste, so a bronchodilator and tolerance assessment may be appropriate. Dornase alfa cleaves extracellular DNA from neutrophils and reduces mucus viscosity. It should not be mixed with other nebulized drugs unless compatibility is established.
Sequence inhaled therapy deliberately
A common individualized sequence is bronchodilator when indicated, hypertonic saline with airway clearance, then dornase alfa according to its schedule, followed by inhaled antibiotic after secretions have been mobilized. The exact timing follows the patient's center plan and product instructions. Inhaled corticosteroids are not routine CF therapy without asthma or ABPA.
Treat the device as part of the dose
Nebulizer system, particle delivery, cleaning, disinfection, drying, replacement, electrical supply, and separation of equipment affect treatment. Verify preparation, storage, breath pattern, dose completion, and time burden. Escalating medication before correcting a failing device preserves inadequate delivery.
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Lesson
Pulmonary Assessment and Exacerbation Recovery
Pulmonary decisions begin with the patient's own baseline. Symptoms, spirometry, oxygenation, microbiology, treatment implementation, and recovery trajectory determine urgency and response.
- Personal pulmonary baseline
- Spirometry and oxygenation
- Exacerbation recognition
- Antibiotic pharmacokinetics
- Recovery and prevention
Know stable function, oxygenation, weight, microbiology, and treatment implementation
Integrate respiratory symptoms, physiology, complications, and alternate diagnoses
Reassess response, toxicity, delivery, prevention, and advanced-care needs
Build a longitudinal pulmonary baseline
Track cough, sputum, exercise tolerance, sleep, appetite, weight, oxygenation, FEV1, imaging, culture history, exacerbations, treatment burden, and adherence over time. A value that appears acceptable in isolation can represent important decline for a patient whose prior function was higher.
Recognize deterioration as a pattern
Increased cough or sputum, dyspnea, fatigue, fever, appetite or weight loss, hemoptysis, oxygen change, new examination findings, and falling spirometry can signal a pulmonary exacerbation. Consider viral illness, asthma, allergic bronchopulmonary aspergillosis, pneumothorax, bleeding, pulmonary embolism, heart disease, and treatment interruption when the pattern is atypical.
Match treatment intensity to severity
Select outpatient, inpatient, oral, inhaled, or intravenous treatment from severity, physiology, prior organisms, resistance, allergies, previous clinical response, organ function, access, and ability to deliver therapy. Increase airway clearance during exacerbation when safe. Aminoglycosides and other high-risk agents require individualized exposure and toxicity monitoring.
Measure recovery and prevent the next event
Reassess symptoms, weight, oxygen, spirometry, adverse effects, microbiology when useful, and return toward the patient's prior baseline. Failure to recover should trigger evaluation of organism coverage, delivery, adherence, complications, alternate diagnoses, and advanced lung disease. Complete the episode with an updated prevention and home-action plan.
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Lesson
Airway Microbiology and Antimicrobial Strategy
CF airway infection changes across age and time. Culture history and clinical response guide eradication, chronic suppression, and acute treatment more reliably than one isolated susceptibility report.
- Culture surveillance
- Initial Pseudomonas eradication
- Chronic inhaled antibiotics
- Azithromycin and NTM safety
- Pulmonary exacerbations
Organism history matters more than one snapshot
Treat new Pseudomonas before chronic adaptation
Match route and intensity to infection state
Read microbiology longitudinally
Staphylococcus aureus, Haemophilus influenzae, Pseudomonas aeruginosa, Burkholderia cepacia complex, Achromobacter, Stenotrophomonas, fungi, and nontuberculous mycobacteria can have different implications. Oropharyngeal, sputum, induced, or bronchoscopy samples have different strengths. Trend organism, density, phenotype, susceptibility, symptoms, imaging, and lung function.
Eradicate new Pseudomonas promptly
Newly acquired Pseudomonas generally triggers an eradication protocol, commonly inhaled tobramycin under center guidance. Routine prophylactic antipseudomonal antibiotic use in culture-negative patients is not the same strategy. Confirm follow-up cultures and avoid declaring eradication solely because symptoms improve.
Suppress chronic infection by route and cycle
Inhaled tobramycin, aztreonam lysine, and other center-directed regimens deliver high airway exposure for chronic Pseudomonas, with product-specific continuous or cyclic schedules. Monitor bronchospasm, voice change, resistance, renal and auditory risk when systemic aminoglycoside exposure occurs, technique, equipment, and adherence. Azithromycin can reduce exacerbations but requires NTM screening and should be withheld with active NTM disease.
Treat each organism in clinical context
Methicillin-resistant Staphylococcus aureus, Burkholderia cepacia complex, Achromobacter, Stenotrophomonas, fungi, and nontuberculous mycobacteria require organism-specific interpretation and specialist input. Distinguish acquisition, chronic infection, colonization, allergic disease, and invasive disease. Antibiotic choice must preserve future options while treating the current clinical problem.
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Lesson
CFTR Modulator Pharmacology and Safety
Modulators act on mutant CFTR protein rather than downstream mucus alone. Product choice is inseparable from genotype, age, weight, formulation, food, interactions, liver monitoring, and current labeling.
- Potentiators and correctors
- Ivacaftor-responsive variants
- Elexacaftor combinations
- Vanzacaftor combination
- CYP3A and hepatic safety
Eligibility follows the exact current product label
Increase selected mutant CFTR at the cell surface
Improve activity of responsive surface protein
Match molecular strategy to available protein
Ivacaftor potentiates responsive CFTR channels at the cell surface. Tezacaftor, elexacaftor, lumacaftor, and vanzacaftor are correctors that improve processing and trafficking for selected mutant protein. Deutivacaftor is a potentiator engineered for prolonged exposure. Combination corrector and potentiator therapy addresses more than one defect.
Use genotype, age, weight, and formulation
Ivacaftor treats patients with at least one responsive variant under its current label. Elexacaftor, tezacaftor, and ivacaftor has broad F508del and other responsive-variant use with age and weight products. Vanzacaftor, tezacaftor, and deutivacaftor is a once-daily option for eligible patients age 6 years and older. Never infer interchangeability from shared ingredients.
Control exposure through food and interactions
Administer labeled modulators with fat-containing food to support absorption. Strong or moderate CYP3A inhibitors require product-specific dose modification. Strong or moderate CYP3A inducers can reduce exposure and are generally not recommended. Review rifamycins, anticonvulsants, azoles, macrolides, herbals, grapefruit, hepatic function, and the exact missed-dose instructions.
Respect current liver, neurologic, mental-health, and eye safety
Current Alyftrek and Trikafta labeling includes prominent drug-induced liver injury and liver failure warnings and scheduled ALT, AST, alkaline phosphatase, and bilirubin monitoring. Current ivacaftor-containing labels also warn about intracranial hypertension. Unusual headache, blurred or double vision, vision loss, nausea, or vomiting requires prompt evaluation. Alyftrek labeling includes serious mental-health events, so new or worsening anxiety, depression, suicidal thoughts, behavior changes, or sleep disturbance requires immediate clinical review. Pediatric patients require baseline and follow-up ophthalmologic examinations for lens opacities.
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Lesson
Pancreatic, Nutritional, GI, and Endocrine Care
Nutrition is a clinical outcome and treatment domain. Pancreatic insufficiency, malabsorption, salt loss, GI disease, CF-related diabetes, and bone disease require coordinated surveillance.
- Pancreatic insufficiency
- PERT calculations
- Fat-soluble vitamins and salt
- CFRD screening
- GI and hepatobiliary disease
Dose lipase to meals, snacks, and feeds
Individualize around malabsorption and current phenotype
Detect silent complications before decline
Replace enzymes with every fat and protein exposure
Pancreatic enzyme replacement provides lipase, protease, and amylase with meals, snacks, formula, and enteral feeds according to product and center plan. Give capsules at the start of eating and distribute during longer meals when directed. Do not crush enteric-coated microspheres or mix them into alkaline food. Persistent symptoms require review of adherence, timing, dose, storage, acid suppression, diet, infection, constipation, and alternate diagnoses.
Calculate in lipase units and protect the colon
Older children and adults commonly use 500 to 2,500 lipase units per kg per meal and half the meal dose for snacks, or a fat-based method. Doses above 2,500 units per kg per meal or 4,000 units per gram of fat require investigation. Avoid exceeding 10,000 units per kg per day. Very high exposure has been associated with fibrosing colonopathy.
Individualize nutrition in the modulator era
Track growth, weight history, body composition, strength, pulmonary status, intake, malabsorption, food access, and cardiometabolic risk. Many patients need energy-dense intake, salt, and CF-specific fat-soluble vitamin replacement, but highly effective modulators can alter weight and metabolic risk. Do not preserve a universal high-calorie prescription when the patient's current phenotype has changed.
Screen for endocrine and GI complications
Annual 75 g oral glucose tolerance testing begins by age 10 for CF-related diabetes screening because A1c alone can miss disease. Insulin remains standard treatment for established CFRD. Monitor constipation and distal intestinal obstruction, reflux, liver disease, gallbladder disease, pancreatitis in pancreatic-sufficient phenotypes, bone health, and CF-specific colorectal cancer risk using current age and transplant guidance.
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Lesson
Endocrine, Bone, Liver, and Cancer Surveillance
Longer survival and multisystem CFTR dysfunction require proactive surveillance for diabetes, bone disease, hepatobiliary disease, colorectal cancer, kidney risk, and treatment-related complications.
- Cystic fibrosis-related diabetes
- Bone health
- Hepatobiliary disease
- Colorectal cancer screening
- Kidney and medication risk
Use OGTT, nutrition, vitamin, fracture, and density context
Connect surveillance to drug dosing, toxicity, and transplant care
Apply CF-specific age, interval, preparation, and symptom evaluation
Detect and treat cystic fibrosis-related diabetes
Annual two-hour 75 g oral glucose tolerance testing begins by age 10 because A1c alone can miss postprandial dysglycemia. Illness, systemic glucocorticoids, pregnancy, and enteral feeding require additional glucose assessment. Established CFRD is treated with insulin while preserving nutrition and pulmonary goals.
Protect bone across the lifespan
Assess vitamin D, calcium intake, nutrition, weight-bearing activity, glucocorticoid exposure, delayed puberty or hypogonadism, fracture history, transplant status, and bone density according to age and risk. Treatment combines correction of reversible factors with pharmacotherapy when indicated.
Recognize hepatobiliary and kidney risk
Follow symptoms, examination, liver chemistry, platelets, imaging, portal-hypertension features, and current CF liver guidance. Review kidney function during nephrotoxic antibiotics, dehydration, aminoglycoside exposure, diabetes, stones, and transplant therapy. Drug doses and monitoring change when organ reserve changes.
Use CF-specific cancer surveillance
Adults with CF have increased colorectal cancer risk, especially after solid-organ transplantation. Screening begins earlier and uses CF-specific preparation and intervals under current guidance. New bleeding, anemia, weight loss, obstruction, or persistent bowel change requires diagnostic evaluation rather than waiting for routine screening.
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Lesson
Longitudinal Safety, Reproductive Health, and Advanced Disease
CF care remains multidisciplinary across changing lung function, treatment burden, mental health, fertility, pregnancy, hemoptysis, pneumothorax, transplant, and aging.
- Quarterly multidisciplinary care
- Infection prevention
- Hemoptysis and pneumothorax
- Reproductive health
- Advanced lung disease and transplant
Integrate lung, nutrition, mental health, and access
Prevent transmission and recognize therapy-changing events
Discuss future options before a crisis
Use an accredited multidisciplinary care model
Pulmonary clinicians, pharmacists, nurses, respiratory therapists, dietitians, social workers, mental-health professionals, genetic counselors, endocrinology, gastroenterology, reproductive specialists, and transplant teams contribute at different stages. Review medication access, treatment burden, adherence, pulmonary function, culture, nutrition, complications, immunization, and goals at regular visits.
Prevent cross-infection without social isolation
Hand hygiene, cough etiquette, equipment cleaning, environmental practices, masking and contact precautions in health care settings, and physical separation between people with CF reduce pathogen transmission. Infection prevention should be practical, clearly taught, and balanced with educational, occupational, and psychosocial participation.
Recognize complications that interrupt routine therapy
Massive hemoptysis, pneumothorax, severe hypoxemia, respiratory failure, or rapidly falling lung function requires urgent specialist care. Temporarily modify airway clearance, aerosol therapy, positive pressure, anticoagulation, or activity according to the complication and center protocol. Do not apply routine clearance through major bleeding or an untreated pneumothorax without review.
Plan reproductive and advanced care early
CF can cause congenital bilateral absence of the vas deferens and reduced fertility through other mechanisms, while modulator therapy may change fertility. Provide contraception, pregnancy, lactation, interaction, and genetic counseling based on current evidence and product labeling. Advanced lung disease care includes oxygen, ventilation, rehabilitation, palliative support, and early transplant referral before a crisis removes options.
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Module practice
Check the connections.
Each attempt draws 10 questions from the complete 120 question bank.
Each attempt draws a fresh set and rearranges the answer choices.
References
Current clinical foundation.
Core source material was synthesized with the following contemporary guidance. Verify local policy and current guidance before applying clinical information.