Cystic Fibrosis – Symptoms and Causes

Overview

Cystic fibrosis (CF) is a genetic disorder that affects several body systems. It causes damage to the lungs, digestive tract, and other vital organs.

CF results from mutations in a specific gene that controls how salt moves in and out of cells. People with CF produce thick, sticky mucus instead of the thin, slippery fluids that normally lubricate the body’s tubes and passageways.

This abnormal mucus clogs airways and other channels throughout the body, leading to serious health problems.

Genetic Basis

CF is an inherited condition that follows a recessive pattern. This means a person must inherit two copies of the defective gene—one from each parent—to develop the condition.

Those who inherit just one copy become carriers who can pass the gene to their children but don’t have symptoms themselves.

The disease appears more frequently in people with North European ancestry, though it can affect individuals of any racial background.

When both parents are carriers, each child has a 25% chance of developing CF, a 50% chance of being a carrier, and a 25% chance of inheriting neither defective gene.

Key Symptoms

Respiratory System Problems:

• Persistent cough with thick mucus
• Wheezing and difficulty breathing
• Reduced exercise tolerance
• Frequent lung infections
• Inflamed nasal passages
• Recurring sinusitis

Digestive System Issues:

• Foul-smelling, greasy stools
• Poor weight gain and growth
• Intestinal blockages
• Severe constipation
• Straining during bowel movements

These symptoms appear because the thick mucus blocks critical pathways in both the respiratory and digestive systems. In the lungs, clogged airways make breathing difficult and create environments where infections thrive.

In the digestive system, the mucus prevents digestive enzymes from reaching the intestines.

Diagnosis

Early detection of CF significantly improves treatment outcomes. All U.S. states now include CF in routine newborn screening programs. When CF is suspected, doctors may use several tests:

1. Family History Assessment: Reviewing the family’s medical history for patterns of inheritance.
2. Genetic Testing: Analyzing DNA samples to identify mutations in the CF gene.
3. Sweat Test: Measuring salt levels in sweat (people with CF have higher salt content).

The sweat test remains the standard diagnostic tool. During this test, a chemical causes sweating on a small patch of skin. The sweat is collected and analyzed for sodium and chloride content.

Treatment Approaches

While there is no cure for CF, treatments can manage symptoms and improve quality of life. Modern approaches include:

Medications:

• Antibiotics to fight lung infections
• Anti-inflammatory drugs to reduce airway swelling
• Mucus-thinning medications to help clear airways
• Digestive enzymes to improve nutrient absorption
• Stool softeners to ease digestive symptoms
• CFTR modulators that target the underlying genetic defect

Airway Clearance Techniques:
These physical therapy methods help loosen and remove thick mucus from the lungs. Techniques include:

• Chest percussion and vibration
• Positive expiratory pressure devices
• High-frequency chest wall oscillation vests
• Exercise programs designed to promote mucus clearance

Surgical Interventions:
In some cases, surgery becomes necessary:

• Nasal and sinus procedures to improve breathing
• Bowel surgery for intestinal blockages
• Organ transplantation (lungs or liver) for severe cases

Daily Management

Living with CF requires a dedicated approach to health management:

Daily Care Activity	Purpose
Airway clearance sessions	Remove mucus from lungs
Medication regimens	Control symptoms and prevent complications
High-calorie, high-protein diet	Meet increased nutritional needs
Regular exercise	Improve lung function and overall fitness
Infection prevention measures	Avoid harmful bacteria and viruses

The complexity of CF care often means patients benefit from specialized treatment centers with teams of doctors, nurses, respiratory therapists, dietitians, and social workers who understand this condition.

Quality of Life

With advances in treatment, people with CF now live longer, healthier lives than in previous generations. Many attend school, build careers, and start families.

The emotional aspects of living with CF are important too. Support groups, counseling, and connections with others who have CF can help people cope with the challenges of this condition.

Research continues to improve understanding of CF and develop new treatments. Clinical trials offer access to cutting-edge therapies, and gene therapy research aims to address the root cause of the disease.

Signs and Symptoms

People with cystic fibrosis often have trouble with their lungs. The thick, sticky mucus builds up in the airways, causing several issues:

• Persistent cough with thick mucus
• Wheezing (a squeaky sound when breathing)
• Quick fatigue during physical activities
• Frequent lung infections
• Stuffy nose and inflamed nasal passages
• Recurring sinus infections

These breathing problems happen because the mucus clogs the tubes that carry air in and out of the lungs. This makes it hard to breathe normally and increases the risk of infections.

Parents might notice a salty taste when kissing their child’s skin, as people with cystic fibrosis have higher salt levels in their sweat. This is one of the first signs many parents notice.

Cystic fibrosis affects digestion by blocking the tubes that carry important digestive enzymes from the pancreas to the small intestine. Without these enzymes, the body can’t properly absorb nutrients from food.

Common digestive symptoms include:

• Foul-smelling, greasy bowel movements
• Poor weight gain and slow growth, especially in children
• Intestinal blockages, particularly in newborns
• Chronic constipation, which can sometimes cause rectal prolapse (where part of the rectum pushes out through the anus)

These problems can lead to malnutrition even when a person eats enough food, because their body can’t use the nutrients properly.

When to Call Your Doctor

Contact your healthcare provider if you or your child shows signs of cystic fibrosis, especially if someone in your family has the condition. Regular check-ups (at least every three months) are important for managing this condition.

Call your doctor if you notice:

• Changes in mucus amount or color
• Unusual tiredness
• Weight loss
• Severe constipation

Seek immediate medical attention if you experience:

• Coughing up blood
• Chest pain
• Breathing difficulties
• Severe stomach pain or bloating

Go to the emergency room or call 911 if:

• You’re struggling to breathe or talk
• Your lips or fingernails turn blue or gray
• You become confused or disoriented

Due to newborn screening, most cases in the U.S. are diagnosed within the first month of life, before symptoms appear. However, people born before this screening became common might not be diagnosed until symptoms develop.

Some people may not show symptoms until their teenage years or adulthood, usually with milder forms of the disease.

Causes

Cystic fibrosis (CF) develops due to mutations in a specific gene called the cystic fibrosis transmembrane conductance regulator (CFTR). This gene plays a crucial role in controlling how salt and water move in and out of the body’s cells.

When the CFTR gene is altered, it affects the protein it produces. This protein normally regulates the flow of chloride ions across cell membranes.

The mutation prevents the protein from working properly, resulting in thick, sticky mucus that accumulates in various body systems.

Scientists classify CFTR mutations into different groups based on how they affect the protein:

• Group 1: No protein is produced.
• Group 2: Protein is made but doesn’t reach the cell surface.
• Group 3: Protein reaches the cell surface but doesn’t function correctly.
• Group 4: Protein reaches the cell surface but has reduced function.
• Group 5: Less protein is produced than normal.

CF follows an autosomal recessive inheritance pattern. This means a person must inherit two copies of the mutated gene—one from each parent—to develop the condition.

People who inherit only one mutated copy become carriers. Carriers typically don’t show symptoms but can pass the mutation to their children.

Risk Factors

Cystic fibrosis is an inherited condition that runs in families. If you have family members with CF, you may face a higher risk of developing the condition.

While cystic fibrosis affects people of all races, it appears most frequently in white individuals with Northern European ancestry. People who are Black, Hispanic, Middle Eastern, Native American, or Asian experience CF less commonly.

This difference in occurrence rates can lead to delayed diagnosis in these populations, which may result in:

• More severe health complications
• Reduced quality of life
• Potentially shorter lifespan

Health Issues

Breathing Problems

Cystic fibrosis (CF) causes several breathing issues. The disease damages airways, leading to bronchiectasis – a condition where airways widen and scar. This makes breathing difficult and mucus hard to clear.

People with CF get many lung infections. The thick mucus in lungs creates perfect conditions for bacteria and fungi to grow. This leads to repeated bronchitis, sinus infections, and pneumonia. Many develop hard-to-treat infections that don’t respond to normal antibiotics.

Nasal polyps (soft growths inside the nose) often develop due to constant irritation and swelling. These can block airways and make breathing harder.

Some patients cough up blood because of damaged airways near blood vessels. While usually minor, this can sometimes become dangerous.

Serious complications include:

• Collapsed Lung (Pneumothorax): Air leaks into the space between the lung and chest wall.
• Respiratory Failure: Lung tissue becomes too damaged to work properly.
• Symptom Flare-Ups: Periods of worse coughing, breathing trouble, and energy loss.

Digestive Issues

CF affects the digestive system in several important ways. Thick mucus can block tubes carrying digestive enzymes from the pancreas to intestines. Without these enzymes, the body can’t properly use:

• Protein
• Fats
• Fat-soluble vitamins

This leads to poor nutrition, weight loss, and delayed growth. Pancreas inflammation (pancreatitis) is common.

CF-related diabetes develops in about 20% of teenagers and up to 50% of adults with CF because the disease affects insulin production.

Liver problems occur when bile ducts become blocked and inflamed, potentially causing:

• Jaundice (yellowing of skin)
• Fatty liver disease
• Cirrhosis
• Gallstones

Intestinal blockages can happen at any age. A particularly serious type called distal intestinal obstruction syndrome (DIOS) occurs where the small and large intestines meet and requires immediate treatment.

Fertility Challenges

Almost all men with CF are infertile. The tube connecting the testicles and prostate gland (vas deferens) is either:

1. Blocked with mucus
2. Missing completely

Men still produce sperm in their testicles, but it can’t reach the semen. Some fertility treatments and surgical procedures may help men become biological fathers.

Women with CF can become pregnant, but they may have more difficulty conceiving than women without CF. Pregnancy can worsen CF symptoms, so it’s important to discuss risks with healthcare providers.

Additional Complications

CF affects many other body systems and functions:

• Bone Health: People with CF have a higher risk of osteoporosis (dangerous bone thinning). Joint pain, arthritis, and muscle pain are also common.
• Electrolyte Imbalance: The saltier sweat caused by CF disrupts mineral balance in blood, increasing the risk. Signs include:
  • Fast heartbeat
  • Extreme tiredness
  • Weakness
  • Low blood pressure
• Digestive Tract Issues: Gastroesophageal reflux disease (GERD) often occurs, where stomach acid flows back into the esophagus, irritating its lining.
• Mental Health: Living with a chronic, incurable condition commonly leads to fear, depression, and anxiety.
• Cancer Risk: People with CF have higher chances of developing cancers in the:
  • Esophagus
  • Stomach
  • Small and large intestines
  • Liver
  • Pancreas

Regular colorectal cancer screening should start at age 40 for CF patients.

Prevention

Genetic testing is an important option for couples with family members who have cystic fibrosis. Blood tests at a laboratory can help determine the risk of having a child with this condition.

For couples already expecting, genetic screening can indicate a potential risk for cystic fibrosis. Healthcare providers can then perform additional testing on the unborn baby to provide more information.

But genetic testing isn’t appropriate for everyone. Consider speaking with a genetic counselor before making this decision. The counselor can help you understand the potential emotional and psychological impacts that test results might have on you and your family.

Testing allows families to make informed decisions about family planning when there’s a history of cystic fibrosis in their families.