Cystic Fibrosis (CF) – Causes, Symptoms, Diagnosis & Treatment

Cystic fibrosis (CF) is a chronic, life-limiting genetic disorder that primarily affects the exocrine glands, leading to the production of thick, sticky mucus. This abnormal mucus causes obstruction of airways, recurrent lung infections, and digestive complications. With modern medicine, early diagnosis and advanced treatment strategies, individuals with cystic fibrosis are living longer and healthier lives than ever before.

Pathophysiology of Cystic Fibrosis

Cystic fibrosis is caused by mutations in the CFTR gene (Cystic Fibrosis Transmembrane Conductance Regulator). This gene is responsible for producing a protein that regulates chloride and sodium ion transport across epithelial cells in the lungs, pancreas, intestines, and sweat glands.

When CFTR is defective, exocrine glands fail to regulate fluid transport properly, resulting in:

• Production of thick, viscous mucus
• Reduced ciliary clearance from the airways
• Increased resistance to airflow
• Mucus plugging, predisposing to infection and tissue damage

The abnormal mucus affects multiple organ systems:

1. Respiratory system – Chronic lung infections, bronchiectasis, airway obstruction.

2. Digestive system – Malabsorption due to pancreatic insufficiency, intestinal blockages.

3. Reproductive system – Infertility in males, reduced fertility in females.

4. Sweat glands – Excessive sodium and chloride in sweat, leading to electrolyte imbalance.

Genetic Basis: An Autosomal Recessive Disorder

Cystic fibrosis follows an autosomal recessive inheritance pattern.

• A child inherits the disease when both parents carry and pass on a mutated CF gene.
• If only one defective gene is inherited, the individual becomes a carrier but does not develop full-blown disease.

This explains why CF can appear in families with no prior history, as parents may unknowingly carry the mutation without showing symptoms.

Clinical Features and Symptoms

Cystic fibrosis presents as a multisystem disorder with variable symptoms depending on organ involvement.

Respiratory symptoms:

• Persistent cough producing thick sputum
• Wheezing and shortness of breath
• Frequent lung infections (pneumonia, bronchitis)
• Nasal polyps and chronic sinusitis

Digestive and nutritional symptoms:

• Poor weight gain despite good appetite
• Greasy, bulky stools (steatorrhea)
• Intestinal obstruction (meconium ileus in newborns, distal intestinal obstruction syndrome in older children)
• Vitamin deficiencies (A, D, E, K due to fat malabsorption)

Other systemic features:

• Clubbing of fingers and toes due to chronic hypoxia
• Salty-tasting skin (due to elevated sweat sodium chloride)
• Male infertility (absence or blockage of vas deferens)

Diagnosis of Cystic Fibrosis

Early diagnosis is crucial for improving prognosis. Common diagnostic methods include:

1. Sweat Chloride Test (Positive Test) – The gold standard; elevated sodium and chloride in sweat (>60 mmol/L) suggests CF.

2. Genetic Screening – Identifies CFTR gene mutations; useful for confirmation and carrier detection.

3. Newborn Screening – Immunoreactive trypsinogen (IRT) test followed by genetic confirmation.

4. Ambry Test – Molecular genetic testing method.

Treatment of Cystic Fibrosis

While there is no complete cure, comprehensive treatment plans help manage symptoms, prevent complications, and improve quality of life.

1. Airway Clearance and Respiratory Therapy

• Chest Physiotherapy (CPT) – Manual percussion, vibration vests, or breathing devices to dislodge mucus.
• Postural drainage – Positioning to help drain mucus from specific lung areas.
• Huff coughing techniques – Controlled exhalation to expel mucus.
• Nebulizers with bronchodilators, mucolytics (dornase alfa), and hypertonic saline to thin mucus.

2. Medications

• Bronchodilators (albuterol, salbutamol) – Open the airways.
• Mucolytics – Break down thick mucus.
• Anti-inflammatories – Reduce lung inflammation.
• Antibiotics – Inhaled, oral, or IV antibiotics to control chronic infections (Pseudomonas aeruginosa, Staphylococcus aureus).
• CFTR modulators – Newer drugs targeting specific gene mutations (ivacaftor, lumacaftor, tezacaftor, elexacaftor).

3. Nutrition and GI Support

Because CF affects digestion, nutritional management is essential:

• High-protein, high-fat, high-calorie diet.
• Fat-soluble vitamin supplementation (A, D, E, K).
• Pancreatic enzyme replacement therapy (e.g., pancrelipase or pancreatin).
• Fluids and stool softeners to prevent gastrointestinal obstruction.
• Enteral feeding support in severe malnutrition.

4. Infection Control

Patients must be vigilant about infection prevention:

• Wearing masks in high-risk environments.
• Frequent handwashing.
• Staying up-to-date with vaccines (influenza, pneumococcal).
• Avoiding contact with individuals who have respiratory illnesses.

Chest Physiotherapy (CPT) in Detail

CPT plays a central role in CF care:

• Drains airways of thick mucus.
• Stimulates cough and loosens secretions.
• Improves deep breathing and cardiovascular fitness.
• Strengthens respiratory muscles.

Guidelines:

• Typically performed multiple times daily at 1–2 hour intervals.
• Avoid sessions right before or after meals.
• Can be performed manually or with vibrating vests.

Prognosis and Life Expectancy

Decades ago, CF was considered a fatal childhood disease. Today, with new treatments and better supportive care, life expectancy has dramatically improved, with many individuals living into their 40s and beyond.

The prognosis depends on:

• Severity of lung involvement
• Access to advanced therapies
• Early diagnosis and adherence to treatment plans

Prevention and Genetic Counseling

Since CF is genetic, prevention focuses on carrier detection and genetic counseling. Couples with a family history of CF or known carrier status may undergo prenatal testing and informed reproductive decision-making.

Table: Cystic Fibrosis at a Glance

Feature	Details
Inheritance	Autosomal recessive (CFTR mutation)
Primary Pathology	Thick mucus due to defective chloride transport
Main Organs Affected	Lungs, pancreas, intestines, reproductive tract, sweat glands
Symptoms	Cough, infections, malabsorption, salty sweat, infertility
Diagnosis	Sweat chloride test, genetic testing, newborn screening
Treatment	CPT, antibiotics, bronchodilators, enzymes, vitamins, CFTR modulators
Nutrition	High calorie, enzyme supplements, fat-soluble vitamins
Prognosis	Chronic, managed lifelong, improved survival with modern therapies

FAQs on Cystic Fibrosis

Q1. Is cystic fibrosis curable?

No. Currently, there is no permanent cure for CF, but modern treatments help manage symptoms and extend life expectancy.

Q2. What is the average life expectancy for cystic fibrosis?

With advanced care, many CF patients now live well into their 40s and 50s, compared to childhood fatality in earlier decades.

Q3. How is cystic fibrosis inherited?

It is an autosomal recessive disorder, meaning a child must inherit two defective CFTR genes (one from each parent) to develop the disease.

Q4. Why do people with CF need pancreatic enzymes?

Thick mucus blocks pancreatic ducts, preventing enzymes from reaching the intestines. Enzyme supplements restore digestion and absorption.

Q5. Can cystic fibrosis patients have children?

Many males are infertile due to congenital absence of the vas deferens. Women may face reduced fertility but can still conceive with medical assistance.

Q6. What are CFTR modulators?

These are breakthrough drugs that target specific CF gene mutations, improving CFTR protein function and overall health outcomes.