Cystic Fibrosis

Definition

Cystic fibrosis (CF) is a genetic condition that affects a protein in the body. People who have cystic fibrosis have a faulty protein that affects the body’s cells, its tissues, and the glands that make mucus and sweat.

Normal mucus is slippery and protects the airways, digestive tract, and other organs and tissues. Cystic fibrosis causes mucus to become thick and sticky. As mucus builds up, it can cause blockages, damage, or infections in affected organs.

Cystic fibrosis used to cause death in childhood. Survival has improved because of medical discoveries and advances in newborn screening, medicines, nutrition, and lung transplants. Nearly 40,000 children and adults in the United States and more than 100,000 worldwide are now living with cystic fibrosis. Children born between 2018 and 2022 who have cystic fibrosis are expected to live an average of 56 years. On average, half of babies born in 2021 with cystic fibrosis are expected to reach the age of 65 or older.

Many people believe that only people who are white get cystic fibrosis. But the disease can occur in anyone and sometimes gets missed in people who are Black.

Although medical advances mean that more people with cystic fibrosis live into adulthood, not everyone gets the same benefits. For example, having a low income is linked with worse lung function, higher death rates, and poorer nutritional status for people with cystic fibrosis. This is true even when comparing groups that have the same number of healthcare visits and take long-term prescription medicines. Also, people of color are more likely to be diagnosed.

Causes

Cystic fibrosis is an inherited disease caused by mutations in a gene called the cystic fibrosis transmembrane conductance regulator (CFTR). The CFTR gene provides instructions for the CFTR protein.

People who inherit two copies of a mutated CFTR gene (one copy from each biological parent) will have cystic fibrosis. Having two mutated CFTR genes means that the body makes a CFTR protein that doesn’t work like it should.

In cystic fibrosis, the mutated CFTR gene changes a protein that regulates the movement of salt in and out of cells. These changes cause thick and sticky mucus and increase the amount of salt in sweat. The abnormal mucus can lead to blockages in and damage to the lungs, the digestive system, and other organs of the body.

Normally, mucus coats tiny hairlike structures called cilia in the airways of your lungs. The cilia sweep the mucus particles up to the nose and mouth so your body can get rid of them. In people who have cystic fibrosis, this process does not work well.

More than 2,000 mutations of the CFTR gene can cause cystic fibrosis. Different mutations affect how much CFTR protein the cells make and how well the protein works. With the most common gene mutation, part of the CFTR gene is missing. The mutation makes a CFTR protein that can’t stay in the correct shape. Some CFTR mutations cause cells to make hardly any CFTR protein at all.

Normally, CFTR protein controls the movement of ions from inside the cell to outside the cell. In people who have cystic fibrosis, the CFTR protein does not work properly. The faulty CFTR protein affects how sodium and water move in and out of cells. Mucus becomes thick and sticky, because it contains less water. Also, sweat glands in the skin make extra-salty sweat.

How is cystic fibrosis inherited?

Every person inherits two CFTR genes: one gene from each parent. Children who inherit a CFTR gene with a mutation from each parent will have cystic fibrosis.

When a mutated CFTR gene is inherited from one parent and a normal CFTR gene is inherited from the other, the person will be a cystic fibrosis carrier. Cystic fibrosis carriers can pass the mutated CFTR gene on to their children. Carriers are generally healthy, but they may have some mild symptoms of cystic fibrosis.

The image below shows how two parents who are both cystic fibrosis carriers can pass a CFTR gene mutation on to their children.

If both parents have a normal CFTR gene and a mutated CFTR gene, each of their children has a:

25% (1 in 4) chance of inheriting two normal CFTR genes
50% (1 in 2) chance of being a cystic fibrosis carrier, because they inherit one normal gene and one mutated gene
25% (1 in 4) chance of inheriting two genes with mutations and having cystic fibrosis

Symptoms

Some people who have cystic fibrosis have few or no symptoms, while others experience severe symptoms or life-threatening complications. The most serious and common complications of cystic fibrosis are problems with the lungs, including frequent pulmonary or respiratory exacerbations, typically caused by serious lung infections.

Diagnosis

Diagnosing cystic fibrosis takes several steps. Your healthcare provider may diagnose cystic fibrosis based on your symptoms and results of genetic and sweat chloride tests.

It is important to diagnose cystic fibrosis as young as possible to start treatment early. Newborn screening makes it possible to detect the disease early in life. Early treatment helps prevent complications and can improve survival.

Universal newborn screening

All newborns in the United States are tested for cystic fibrosis. Newborn screening identifies more than half of cystic fibrosis cases. However, many people born before 2010 have not been screened.

Newborn screening for cystic fibrosis is performed during a baby’s first 2 to 3 days of life. A few drops of blood from a heel prick are placed on a special card and tested by a lab.

Every state and the District of Columbia begin screening with a blood test to check for levels of immunoreactive trypsinogen (IRT), a chemical made by the pancreas. In people who have cystic fibrosis, IRT tends to be high. However, most babies with high levels of IRT do not have cystic fibrosis. IRT can also be high for other reasons, such as if the baby was born preterm (premature), had a stressful birth, or is a carrier of cystic fibrosis.

Some states test only IRT for cystic fibrosis newborn screening. In other states, if IRT is high, then the hospital will test the baby’s DNA for some of the CFTR mutations that cause cystic fibrosis. After a positive screening test, diagnosis is confirmed with more tests.

Genetic testing may be used to look for carriers of mutated CFTR genes and to screen relatives of people who have cystic fibrosis. Genetic testing looks at your DNA from a blood or saliva sample or cells from the inside of your cheek.

Genetic testing can tell you whether you are a carrier of a mutated CFTR gene. This is called carrier screening. It is your choice whether to have this test. People who inherit a mutation of the CFTR gene from one parent are cystic fibrosis carriers. People who have inherited a mutation of the CFTR gene from both parents will have cystic fibrosis. Learn more about how cystic fibrosis is inherited.

The standard test to check for cystic fibrosis carriers looks for 23 or more of the most common disease-causing gene mutations. If your test did not identify a CFTR mutation, there is still a small chance that you could carry a type of mutation that did not show up on the test.

Siblings (brothers and sisters) of a person who has cystic fibrosis may want to be tested for cystic fibrosis even if they do not have symptoms. Other family members, such as first cousins and half-siblings, may be tested if they have symptoms or if the family is concerned that those individuals might have cystic fibrosis or be carriers.

After a positive or unclear screening test result, the diagnosis should be confirmed with further testing. A genetic counselor can help you understand the meaning of your carrier screening result.

Preconception and prenatal screening

Genetic tests done before or during pregnancy can look for a mutated CFTR gene. The tests use a sample of blood, saliva, or cells from the inside of your cheek to check your DNA. It is your choice whether to have this screening. Talk with your healthcare provider about screening if you’re thinking about getting pregnant or if you’re already pregnant.

Couples who are planning to have children may want to be tested to see whether they are cystic fibrosis carriers. Getting tested before pregnancy gives you more options and more time to make decisions if results show that one or both parents has a mutated CFTR gene.

Often the mother is tested first. If the father has a family history of cystic fibrosis, he may be tested first. If one parent is a carrier for a CFTR gene mutation, then the next step is to test the other parent.

If you are already pregnant, both parents may be tested at the same time. If you are both cystic fibrosis carriers, then prenatal diagnostic testing may be performed to check the unborn baby for mutated CFTR genes.

Sweat test

A sweat test checks for high levels of chloride in your sweat. The sweat test is the standard test for diagnosing cystic fibrosis. It may be used if you have symptoms that could indicate cystic fibrosis or to confirm a positive diagnosis from a screening of your newborn baby. A normal sweat chloride test result alone does not mean you do not have cystic fibrosis. Lower levels of chloride may indicate the need for further testing to diagnose or rule out cystic fibrosis.

The sweat test detects a higher amount of chloride — a component of salt — in the sweat of people who have cystic fibrosis. In order to produce sweat for this test, a colorless, odorless chemical and a little electrical stimulation are applied to a small area of a person’s arm or leg. The sweat is collected and sent to a hospital lab for testing.

Treatment

Although there is not yet a cure for cystic fibrosis, advances in treatment are helping many people live longer, healthier lives. To manage the disease, you will work with a team of healthcare providers, including cystic fibrosis specialists. For newborns with a positive screening result, treatment may begin while the diagnosis is being confirmed.

Treatment for cystic fibrosis focuses on medicines and other ways to clear the airway. Other medicines can improve the function of the faulty CFTR protein and help prevent complications. Sometimes breathing support, nutritional support, or surgery is needed.

Your healthcare providers will likely include a cystic fibrosis specialist. This is a doctor who is familiar with the complex nature of cystic fibrosis.

Your cystic fibrosis care team may include:

Doctors specializing in the lungs, diabetes, and the digestive system
Fertility and reproductive health specialists
Genetic counselors
Nurses
Nutritionists and dietitians
Palliative care specialists
Pharmacists
Physical therapists
Psychologists
Research coordinators
Respiratory therapists
Social workers
Transplant doctors and nurses

Airway clearance techniques

Airway clearance techniques help loosen lung mucus so it can be cleared, reducing infections and improving breathing. The techniques may include special ways to breathe and cough, devices used by mouth, therapy vests that use vibrations to loosen mucus, and chest physical therapy. These techniques are often used along with medicines such as bronchodilators (medicines that open up the airways) and mucus thinners.

Medicines

Medicines to treat cystic fibrosis may maintain and improve lung function, fight infections, clear mucus and help breathing, or try to improve how well someone’s CFTR protein works.

Antibiotics prevent or treat lung infections and improve lung function. Your healthcare provider may prescribe oral, inhaled, or intravenous (IV) antibiotics.
Anti-inflammatory medicines, such as ibuprofen or corticosteroids, reduce inflammation. Inflammation causes many of the changes in cystic fibrosis, such as lung disease. Ibuprofen is especially helpful for children, but side effects can include kidney and stomach problems. Corticosteroids can cause bone thinning and increased blood sugar and blood pressure.
Bronchodilators relax and open airways. These treatments are taken by inhaling them.
CFTR modulators improve how a faulty CFTR protein works. They help with lung function and can help prevent lung problems or other complications. Not all CFTR modulators work for all people with cystic fibrosis. The choice of CFTR modulator depends on which CFTR gene mutation you have. Before you start taking a CFTR modulator, your healthcare provider or a genetic counselor will order genetic testing to figure out whether a CFTR modulator therapy is likely to work for you. These medicines are taken by mouth. Some CFTR modulators may interact with other medicines, including birth control pills. They may cause side effects, including temporary worsening of breathing symptoms, nasal or sinus congestion, headache, or abdominal pain. There are several CFTR modulator therapies approved for use in cystic fibrosis:
- A triple combination medicine (elexacaftor-tezacaftor-ivacaftor) is the first approved treatment and may help up to 90% of people who have cystic fibrosis. It is currently approved for adults and children age 2 and older with certain CFTR mutations.
- Ivacaftor is approved for adults and children as young as 4 months old.
- A combination of lumacaftor and ivacaftor is approved for people who are at least 1 year old.
- A combination of tezacaftor and ivacaftor is approved for people as young as 4 months old.
People who are Asian, Black, or Hispanic are more likely to have mutations that won’t respond to available CFTR modulators.

If you are not eligible for treatment with a CFTR modulator, your healthcare provider may recommend participating in a clinical trial. Scientists continue to work on new treatments for cystic fibrosis.

It can be very hard for people to find out that CFTR modulators won’t work for them because of the type of CFTR gene mutation they have. It is common to feel depressed or anxious if you learn that you are not eligible for CFTR modulators. Talk with your healthcare team about mental health support and other treatment options for you.
Mucus thinners make it easier to clear the mucus from your airways. These treatments are taken by inhaling them.

Breathing support

People living with cystic fibrosis who have severe lung problems sometimes need other treatments too.

Oxygen therapy gives you more oxygen to breathe. You can receive oxygen therapy from tubes placed in your nose, a face mask, or a tube placed in your trachea (windpipe).
Pulmonary rehabilitation is a supervised medical program that helps people who have lung diseases live and breathe better. During the program, you will learn exercises and breathing techniques.
Ventilator support uses a machine to blow moist air into your lungs through a breathing tube or tightly fitting mask. Your healthcare provider sets the ventilator to control how often it pushes air into your lungs and how much air you get.
Extracorporeal membrane oxygenation (ECMO) pumps your blood through an artificial lung to add oxygen and remove carbon dioxide before returning the blood to your body. Healthcare providers use ECMO to treat people with severe breathing problems. It may be used for several days or weeks to give the lungs a chance to recover. Some complications of ECMO are blood clots, bleeding, and infections, all of which can be life-threatening.

Other complications may include clogging of the feeding tube, infection or pain at the tube insertion site, constipation, or diarrhea.

Surgery

Surgery may be needed for people with advanced conditions.

A lung transplant may help people with severe lung disease and respiratory failure.
A liver transplant may be an option for advanced liver disease such as cirrhosis.

Living With

Most people who have been diagnosed with cystic fibrosis are living well into adulthood. Many go on to attend college or pursue other education, get jobs, and have families.

Your quality of life and survival depends on understanding how cystic fibrosis affects health and taking steps to avoid complications. Follow your treatment plan, and see your healthcare provider regularly. Avoiding infections and finding emotional support are also important.

How cystic fibrosis affects your health

Cystic fibrosis affects many body parts and systems. Complications depend on which organs are affected and how severe your condition is.

Possible complications include:

Allergic bronchopulmonary aspergillosis (ABPA), an allergic reaction in the lungs to the fungus Aspergillus
Bladder control problems
Bronchiectasis, a common complication of cystic fibrosis caused by long-term inflammation or obstruction of the airways
Cancer of the digestive tract, including the esophagus, stomach, small bowel, large bowel, liver, and pancreas. Because of a higher risk of colorectal cancer, regular screenings beginning at age 40 is recommended.
Chronic lung infections, most commonly with the bacteria Staphylococcus aureus (“staph”) and Pseudomonas aeruginosa
Collapsed lung, resulting in air in the space between the lung and chest wall (called pneumothorax)
Diabetes caused by damage to the pancreas, the organ that makes insulin
Fertility problems
Gastrointestinal problems, such as distal intestinal obstruction syndrome (DIOS), when the intestine becomes blocked by very thick intestinal contents
Heart failure caused by lung damage
Hemoptysis , or coughing or spitting up of blood
Kidney problems from diabetes, some antibiotics, or kidney stones
Liver disease or failure caused by blockage of the bile ducts in the liver, which may lead to cirrhosis and a need for a liver transplant
Lung infections that may come back or be difficult to treat
Malnutrition, because the pancreas may not make enough enzymes to help digest and absorb nutrients from food. Nutritional deficiencies may include low levels of vitamins A, D, E, and K.
Mental health problems, such as depression and anxiety
Muscle and bone complications, including osteoporosis, joint pain, arthritis, and muscle pains
Pancreatitis
Pulmonary exacerbations, episodes of worsening cough, shortness of breath, and mucus production caused by airway inflammation and blockage from an increase in bacteria in the airways and lungs
Salt loss syndrome, in which the body quickly loses salt, or sodium and chloride, causing electrolyte and other imbalances

Regular checkups with your healthcare provider are an important part of your follow-up and treatment. How often these checkups take place depends on your age. Younger people and those who have just been diagnosed will have more frequent visits. As an adult, you may see your provider less often, maybe every 3 months and then once a year for an evaluation.

Regular checkups may include:

Education about the importance of following treatment recommendations such as airway clearance therapies, infection control, taking medicines as prescribed, and other steps to lower your risk of complications
Height and weight measurement and calculation of body mass index (BMI)
Nutrition guidance, including regular assessments and a personalized food plan to meet your energy and nutrition goals
Physical activity guidance
Physical exam, including examination of the heart, lungs, and abdomen to check the liver and look for abdominal pain
Physical therapy evaluation and needs
Psychological assessment and support
Respiratory therapy evaluation and needs
Screening for colorectal cancer

Monitor your condition

In addition to more frequent regular checkups, you may need to see your providers for other tests.

Abdominal ultrasound or a computed tomography (CT) scan can look for the cause of abdominal pain, check the pancreas and liver, and look for intestinal blockages.
Blood tests check for diabetes; infection; liver disease; side effects of medicines, such as damage to kidneys; nutritional status, including complete blood count; and vitamin levels.
Bone mineral density tests check for osteopenia or osteoporosis in those who are at risk. You may be at risk if you take corticosteroids long-term, have severe lung disease, or do not get enough nutrition. Testing of bone mineral density may be done with an X-ray test called a dual-energy X-ray absorptiometry (DEXA or DXA) scan.
Lung imaging tests look for changes in lung function or lung infection. Early changes may be seen before you notice symptoms. In younger children, this may be done every other year to reduce radiation exposure.
Blood sugar testing checks for and monitors diabetes linked with cystic fibrosis.
Pancreas function testing may include looking at an enzyme called pancreatic elastase-1 in your stool.
Lung function tests include checking oxygen levels in your blood and spirometry. Spirometry is the most important and most widely used tool to assess lung function in cystic fibrosis. Regular spirometry is used to monitor lung function in people age 6 and older and may be done in children as young as age 3.
Respiratory sample smear and culture involves taking airway secretion or mucus samples every 3 months to look for microorganisms in the respiratory tract and, if necessary, treat them.

Health Awareness for Carriers

If you are a carrier, you may have some mild cystic fibrosis symptoms. Talk with your healthcare provider about ways to lower your risk of complications. Your provider may recommend extra screening tests for colorectal cancer. Limiting the amount of alcohol you drink may lower your risk of pancreatitis.

Healthy lifestyle changes

Staying as healthy as possible is a very important part of cystic fibrosis care. Your healthcare provider will work with you to make a plan for lifestyle changes that can become part of your everyday life.

Your provider may talk to you about healthy lifestyle changes to help keep cystic fibrosis symptoms in check and reduce your risk of complications.

Choose healthy foods to improve overall health. Follow the nutrition plan you set up with your nutritionist or dietician. You may need to increase your food or calorie intake by eating more foods or by eating high-energy foods. A high-sodium eating plan or a sodium supplement may be recommended at times. With newer, effective treatments for cystic fibrosis, some people may have a higher risk for overweight and obesity. Check with your provider about keeping your weight in a healthy range.
Be physically active to improve your ability to exercise and stay active. Children and adults can work with their healthcare providers to set up a program that is specific to their own needs and abilities. Physical activity may improve lung function, help with airway clearance, build up strength, and help keep body weight in a healthy range. Before starting any exercise program, check with your healthcare provider. Your provider may suggest an exercise test to see what level of physical activity is right for you.
Manage stress. Relaxation techniques may help improve your quality of life. Talk to your healthcare provider or meet with a mental health professional if you feel anxious, depressed, or have panic attacks.
Quit smoking. Smoking tobacco and inhaling secondhand smoke increase your risk of complications. For children who have cystic fibrosis, secondhand smoke is linked with worse lung function and slower growth. CFTR modulator drugs may not work well for children who are exposed to secondhand smoke. Smoking is linked with pancreatitis, which is also a complication of cystic fibrosis. Vaping electronic cigarettes (e-cigarettes) may also increase your risk of complications.
Limit alcohol. Talk to your healthcare provider about how much alcohol you drink. They may recommend that you reduce your alcohol intake or stop drinking alcohol. If you do not drink, you should not start. Limiting the amount of alcohol you drink may lower your risk of pancreatitis. You should not drink if you are pregnant, under age 21, taking certain medicines, or have certain medical conditions, including cystic fibrosis.
Try to get good-quality sleep. Getting quality sleep is often hard with cystic fibrosis. If you have trouble sleeping, ask your healthcare provider about a sleep test and treatments that may help improve your sleep. Develop healthy sleep habits by going to sleep and getting up at regular times, following a calming bedtime routine, and keeping your bedroom cool and dark.

Prevent infections

Despite major progress treating cystic fibrosis, infections remain a serious problem. They can lead to worsening lung disease or death.

Hygiene

People with cystic fibrosis can spread certain infections to others who have the disease. To protect each other, people with cystic fibrosis should stay 6 feet apart. This advice does not apply to people in the same household.

Family members and other close contacts can also spread infections to people with cystic fibrosis. Ask your healthcare provider about steps you and your family can take to prevent the spread of germs and other microbes that can cause cystic fibrosis complications. Your healthcare providers should also take precautions to protect you from infections when you visit.

Vaccinations

Vaccines are important for preventing complications among people with cystic fibrosis. Children and adults with the condition should follow U.S. vaccine standard recommendations. It is especially important to stay up to date on vaccines that protect the lungs:

Annual influenza (flu) shots
COVID-19 vaccine and booster shots at the recommended times
Pertussis (whooping cough) vaccine
Pneumonia vaccine when appropriate, based on your age or risk factors

Family members and other close contacts should also get vaccinated to help protect you.

When to call your healthcare provider

Talk with your healthcare provider about how often to schedule office visits, lung function tests, and blood tests. Between visits, call your provider if you get new symptoms, your symptoms worsen, or you have problems with your blood sugar.

Let your provider know if you are having problems with any part of your treatment plan. Even if your symptoms get better, be sure to see your providers regularly for ongoing care.

Call your provider if your lung symptoms get worse, you start coughing or spitting up blood, or you have sudden shortness of breath or chest pain. Also contact your provider if you get severe belly pain that spreads to the chest or back, which may be a symptom of pancreatitis.

When to call 9-1-1

If you have respiratory failure, your symptoms may suddenly get worse. Call 9-1-1 for help if you suddenly have trouble breathing or talking, you feel confused, or your family or caregivers notice a bluish color on your skin or lips.

It is common for people with serious illnesses, including cystic fibrosis, to feel anxious or sad and depressed at times.

You may worry about having health problems or keeping up with your treatment plan. By lowering your stress levels and learning coping skills, you may be able to improve your quality of life. Talk with your healthcare provider about how you feel. They may recommend you look for additional support.

Join a patient support group. This may help you adjust to living with cystic fibrosis. You can find out how other people manage similar problems. Your provider may be able to recommend local support groups, or you can check with an area medical center.
Seek support from family and friends. Let your loved ones know how you feel and what they can do to help you relieve stress and anxiety.
Talk to a professional counselor. If you have depression or anxiety, medicines or other treatments can improve your quality of life.

Know your options with advanced disease

While the quality of life and survival of individuals with cystic fibrosis continue to improve, the disease can still cause life-threatening complications. Long-term inflammation can damage lung tissue and eventually lead to respiratory failure. Advanced cystic lung disease remains common and is the most frequent cause of death for people with the condition.

Getting the right care for advanced disease means planning ahead. Think about what matters to you and learn about your treatment options from your healthcare provider. Include your trusted caregivers in regular discussions about your preferences and plans.

For people with advanced conditions, palliative or hospice care can improve quality of life and make daily life more comfortable. This care focuses on managing your symptoms, helping you avoid unnecessary tests or treatments, and providing support to your loved ones.

Definition