Cystic fibrosis is a disease that causes the body to produce thick, sticky mucus. As the mucus builds up in the lungs, it blocks the airways and promotes the growth of bacteria. As a result, patients experience chronic lung infections that cause increasing damage to the lungs.
The mucus also may block ducts in the pancreas, which prevents digestive enzymes from reaching the small intestine. Without these enzymes, the body cannot fully absorb fats and proteins. This can lead to malnourishment and other symptoms. Cystic fibrosis also may create mineral imbalances, affect the liver and result in infertility.
A defect in the gene known as cystic fibrosis transmembrane conductance regulator (CFTR) causes cystic fibrosis. Everyone inherits one copy of the CFTR gene from each parent. When both parents pass on an abnormal CFTR gene, the child will have cystic fibrosis.
Symptoms of cystic fibrosis vary from patient to patient. Many patients with mild forms of this illness do not experience symptoms until they reach adolescence or young adulthood. Once symptoms appear, they are usually related to the thick, sticky mucus that is characteristic of the disease. Even if the symptoms are initially mild, they usually get steadily worse over time.
Most children who have cystic fibrosis are diagnosed by the time they are 3 years old, although milder forms of the illness may not be diagnosed until the teen years. Various tests are performed to diagnose the disease, including a sweat test that looks for abnormally high concentrations of salt in perspiration.
There is no known cure for cystic fibrosis. Treatments focus on improving the patient's capacity to breathe and eliminating infections. Chest physical therapy (CPT) is commonly used to loosen mucus. In this therapy, patients are gently but firmly pounded on the chest and back to dislodge mucus from the lungs. Medications also may help alleviate infections and other symptoms.
Although patients cannot prevent cystic fibrosis, they can take several steps that may reduce symptoms or make them more manageable. Patients are encouraged to lead a healthy lifestyle, including eating a well-balanced diet, exercising regularly and avoiding smoking.
Decades ago people with cystic fibrosis never survived to adulthood, but medical advances have increased the average life span to more than 35 years, according to the National Institutes of Health (NIH).
About cystic fibrosis
Cystic fibrosis is a condition that causes the body to produce thick, sticky mucus. This inherited disease most often causes health problems that affect the lungs, pancreas, liver, reproductive organs and sinuses. About 30,000 Americans and 70,000 people worldwide have cystic fibrosis, according to the Cystic Fibrosis Foundation. It is the most common serious genetic disease in white Americans.
In a healthy person, mucus is watery and helps keep the linings of organs moist. This prevents them from drying out and becoming infected. Mucus also helps protect the openings to the body. In cystic fibrosis, a genetic abnormality causes the body to produce thick, sticky mucus that is characteristic of the disease.
As the mucus builds up in the lungs, it blocks the airways and creates an environment in which bacteria can grow. As a result, patients experience chronic lung infections that cause cumulative (increasing over time) damage to the lungs. The infections in people with cystic fibrosis are most frequently caused by the bacterium Pseudomonas aeruginosa, which rarely causes infections in people without the disease.
The mucus also may block ducts in the pancreas, which prevents the digestive enzymes made by the pancreas from reaching the small intestine. Without these enzymes, the body cannot fully absorb fats and proteins. This can lead to malnourishment, bulky stool, a lack of certain vitamins (A, D, E and K), and other symptoms such as intestinal gas, a swollen abdomen, and pain or discomfort.
The abnormal gene that triggers cystic fibrosis also causes sweat to become very salty. During heavy perspiration, the body may experience a mineral imbalance that may require emergency treatment.
Respiratory failure is the chief cause of death in patients with this illness. However, medical advances have increased the average life span of a person with cystic fibrosis to more than 35 years, according to the National Institutes of Health.
Possible complications of cystic fibrosis
Possible complications associated with cystic fibrosis include:
Bronchiectasis. Lung disease in which the bronchial tubes become stretched out and form pockets where mucus collects. Bacteria grow in the mucus, causing repeated lung infections.
Clubbing. Widening and rounding of the tips of the fingers and toes. It occurs when the lungs fail to move enough oxygen into the bloodstream.
Collapsed lung (pneumothorax).
Diabetes. Cystic fibrosis-related diabetes (CFRD) shares some features of type 1 diabetes and some features of type 2 diabetes. Between 10 and 20 percent of cystic fibrosis patients develop CFRD, according to the Cystic Fibrosis Foundation.
Gallstones. Solid deposits formed in the gallbladder or nearby ducts that may cause ducts to become blocked.
Intestinal blockage. This complication particularly affects newborns.
Liver disease. Results from inflammation of or blocked bile ducts.
Low bone density. Results from a lack of vitamin D, and can lead to osteoporosis.
Nasal polyps. Growths that develop in the nose that may require surgery.
Pancreatitis. Inflammation of the pancreas.
Rectal prolapse. Chronic coughing and difficulty passing stool can force rectal tissue to move outside of the rectum.
Sinusitis. Swelling of the air-filled spaces behind the eyes, forehead and nose. As the sinuses swell, they become blocked with mucus that creates a breeding ground for infection.
Intussusception. Condition in which one part of the intestines displaces another part. This tends to occur in children older than 4 years of age.
Infertility also can be a complication for many adult patients with cystic fibrosis. Most men with cystic fibrosis are infertile because the gene that causes thick mucus also interferes with the action of the vas deferens, the tube that transports sperm away from the testicles. Women usually remain fertile but may have lowered fertility rates. However, both men and women with cystic fibrosis often can take advantage of new reproductive technologies to become a parent.
Risk factors and causes of cystic fibrosis
An abnormality in the gene known as cystic fibrosis transmembrane conductance regulator (CFTR) causes cystic fibrosis. This gene is responsible for making a protein that regulates the movement of salt and water into and out of the body's cells. When this gene is defective, it causes the body to produce the thick, sticky mucus and salty perspiration characteristic of cystic fibrosis.
Everyone inherits one CFTR gene from each parent. When both parents pass on an abnormal CFTR gene, the child will have cystic fibrosis. Children who inherit one abnormal gene and one normal gene will not develop cystic fibrosis and will experience no symptoms. However, they will be carriers of the condition and may pass it on to any future children. About 12 million Americans are carriers of this abnormal gene, according to the National Institutes of Health (NIH).
It is important to remember that parents who are carriers have both normal and abnormal CFTR genes. Therefore, even if both parents are carriers, it does not mean they will always pass the abnormal CFTR gene on to their child. When two people who are both carriers of an abnormal CFTR gene (but who do not have the condition) have a baby, the child has the following odds of developing cystic fibrosis:
One in four chance of inheriting two abnormal CFTR genes and developing cystic fibrosis.
One in four chance of inheriting two normal CFTR genes and not developing cystic fibrosis and not becoming a carrier.
Two in four chance of inheriting one normal CFTR gene and one abnormal CFTR gene. In this instance, the child will not develop cystic fibrosis but will be a cystic fibrosis carrier.
Cystic fibrosis affects both males and females and people from all racial and ethnic groups. However, it is most common among Caucasians of Northern European descent. It also is relatively common among Latinos and Native Americans (particularly the Pueblo and Zuni). It is less common among people of African and Asian descent.
Signs and symptoms of cystic fibrosis
Symptoms of cystic fibrosis vary from patient to patient. Many patients with mild forms of this illness do not experience symptoms until they reach adolescence or young adulthood. Once symptoms appear, they are usually related to the thick, sticky mucus that is characteristic of the disease. Even if symptoms are initially mild, they usually get steadily worse over time.
Additional symptoms most often involve lung and digestive problems. They may include:
Chronic coughing, including expulsion of thick mucus
Regular episodes of bronchitis and pneumonia that may cause inflammation and permanent lung damage
Salty-tasting skin
Dehydration
Infertility (mostly in men)
Chronic diarrhea or bulky, light-colored, foul-smelling, greasy stool
Big appetite, but inability to gain weight (failure to thrive)
Fatigue
Frequent sinus infections
Intestinal blockage in newborns
Stomach pain and discomfort resulting from too much gas in the stomach
Persistent wheezing
Poor height growth
Diagnosis methods for cystic fibrosis
Some states screen all newborns for cystic fibrosis. Most children who have cystic fibrosis are diagnosed by the time they are 3 years old, although milder forms of the illness may not be diagnosed until the teen years. In diagnosing cystic fibrosis, a physician will perform a physical examination and review the medical history. If cystic fibrosis is suspected, various tests may be performed to confirm the diagnosis. These include:
Sweat test. The sweat test is the most common diagnostic test for cystic fibrosis. A small amount of a chemical called pilocarpine is rubbed on the patient's arm or leg. An electrode that generates a small, painless electric current is placed on the spot to induce sweating. A gauze pad or filter paper is used to cover the spot for about 30 minutes. The sweat collected is then analyzed and the level of chloride (a chemical in salt) present is measured. High levels of chloride may indicate cystic fibrosis. The test cannot indicate the severity of cystic fibrosis.
Lung function tests. These tests can reveal how much air the patient’s lungs can hold. Testing also can reveal how quickly air is breathed into and out of the lungs, and how efficiently the lungs add oxygen to and remove carbon dioxide from the lungs.
Blood tests. A blood sample can be used in genetic testing to identify any abnormality of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which may indicate cystic fibrosis. Blood testing also can reveal other abnormalities associated with cystic fibrosis. In some states, blood testing is being used to test all newborns for cystic fibrosis.
Fecal tests. A stool sample can reveal the presence of abnormal levels of fats, which people with cystic fibrosis typically cannot fully digest.
Chest x-ray. This imaging test can reveal scarring resulting from the chronic inflammation associated with cystic fibrosis.
Sinus x-ray. This imaging test can reveal inflammation of the sinuses, which is often associated with cystic fibrosis.
Sputum cultures. A sample of mucus can be analyzed for the presence of bacteria growing within it. Bacterial infections are common in people with cystic fibrosis.
It is recommended that children with cystic fibrosis receive regular medical examinations at a healthcare facility that specializes in the disease. These facilities can also help with dietary and therapy questions, and serve as a resource for caregivers and patients.
Women who are pregnant can undergo prenatal testing that may reveal whether or not a fetus has cystic fibrosis. During an amniocentesis, a physician inserts a hollow needle through the abdominal wall of the uterus and obtains cells from the fluid surrounding the fetus. The fluid is analyzed to see whether the CFTR genes of the fetus are normal.
Chorionic villus sampling is another prenatal testing technique. Ultrasound is used to guide a thin tube into the uterus. A tiny piece of the placenta is then removed and analyzed. If the fetus has cystic fibrosis, the condition will be revealed in the cells of the placenta.
Finally, people can be tested before they have children to determine whether or not they are carriers of abnormal CFTR genes. A blood or saliva sample can allow examination of the CFTR gene. Such testing is about 90 percent accurate, according to the National Institutes of Health (NIH). However, there are hundreds of specific cystic fibrosis gene mutations, and not all of them are known. As a result, genetic testing does not detect everyone who is a carrier of cystic fibrosis. People who undergo genetic testing are advised to have genetic counseling.
Treatment options for cystic fibrosis
There is no known cure for cystic fibrosis. Treatments focus on improving the patient’s capacity to breathe and eliminating infections.
Chest physical therapy (CPT) is a technique commonly used to loosen mucus. In this therapy, patients are gently but firmly pounded on the chest and back to dislodge mucus from the lungs. The movement involved is sometimes called chest clapping or percussion. The patient then coughs up the mucus. Chest clapping usually is performed two to four times daily. During CPT, patients may either sit or lie on their stomachs with head down. This allows gravity to help drain the mucus from the lungs.
Devices have been developed that can aid CPT. These include an electric chest clapper (also known as a mechanical percussor), inflatable therapy vest (which uses high-frequency airwaves to force mucus from the lungs), a “flutter” device (causes vibrations that dislodge mucus) and positive expiratory pressure (mask that creates vibrations that break mucus loose from airway walls). Children typically require the assistance of a therapist or caregiver in performing CPT. Adult patients or patients in their teens may learn techniques to perform CPT alone or with mechanical aids.
Certain breathing techniques can also help loosen mucus. The forced expiration technique involves forcing out two breaths and then engaging in relaxed breathing. Active cycle breathing uses the same technique, but also focuses on deep breathing exercises to help loosen mucus.
Regular aerobic exercise also can increase a person’s lung capacity, loosen mucus and trigger coughing that helps clear the mucus. Patients who exercise regularly may be able to reduce their need for CPT.
Infections of the airways tend to be ongoing and low-grade in patients with cystic fibrosis. In some cases, these infections are serious enough that they may require hospitalization. Antibiotics are used to treat these infections. Oral antibiotics may be used to treat relatively mild infections. Inhaled (aerosolized) and intravenous (into a vein) antibiotics may be used for more significant infections.
Other medications that may be used to treat cystic fibrosis include:
Bronchodilators. Inhaled drugs that function by relaxing the muscles around airways, allowing the airways to open. They usually are taken just before CPT to help clear mucus.
Corticosteroids. These drugs reduce inflammation around the lungs.
Ibuprofen. An over-the-counter or prescription nonsteroidal anti-inflammatory drug (NSAID) that may help reduce the progression of cystic fibrosis in young children.
Insulin. This diabetes drug may be prescribed for patients with cystic fibrosis-related diabetes (CFRD).
Mucus-thinning drugs. These medications reduce the stickiness of mucus in the airways.
Enzymes and nutritional medications. People with cystic fibrosis, particularly children, may require oral pancreatic enzymes to aid in digestion of fats and proteins and absorption of vitamins. A physician also may recommend a high-calorie diet and vitamin supplements.
Feeding tubes may be necessary for patients who are at risk of malnutrition and who do not respond to other nutrition therapies. Some patients may require the implantation of a gastrostomy tube that can be used to deliver nutrients directly into the stomach. These tubes may be used in children at night to provide nourishment while asleep.
Patients who do not receive adequate levels of oxygen may require oxygen therapy. This is usually delivered through oxygen prongs or a mask.
In severe cases, patients may benefit from lung transplantation. Many factors help determine whether a person is a good candidate for transplantation. These include the type of bacteria present in the lungs, patient age and weight, and the nature of the patient's other medical conditions. Both lungs require transplantation in people with cystic fibrosis, which may reduce the availability of donor organs.
Researchers are investigating potential treatments for cystic fibrosis, including gene therapy and new medications.
Lifestyle considerations with cystic fibrosis
Although patients cannot prevent cystic fibrosis, they can take several steps in their day-to-day lives that may reduce symptoms or make them more manageable. Patients with cystic fibrosis are encouraged to lead a healthy lifestyle, including eating a well-balanced diet, exercising regularly and avoiding smoking.
Patients are also encouraged to do the following:
Engage in chest physical therapy (CPT) every day
Wash hands frequently to reduce the risk of infections
Drink plenty of fluids
Receive annual flu vaccines and other recommended vaccinations
Take medications as prescribed
Children who have cystic fibrosis often require a high-protein, high-calorie diet to help them gain weight and grow properly. Parents are urged to consult with a physician about the best diet to help children achieve their caloric requirements.
In the 1950s people with cystic fibrosis died in early childhood, but the predicted median age of survival increased to 32 years in 2000 and 36.5 years in 2005, according to the Cystic Fibrosis Foundation. People with the disease may complete college, have careers, marry and have family. Some patients live to their 40s and beyond.
Questions for your doctor about cystic fibrosis
Preparing questions in advance can help patients to have more meaningful discussions with healthcare professionals regarding their condition. Patients may wish to ask their doctor the following questions related to cystic fibrosis:
What are the first symptoms of cystic fibrosis that I’m likely to notice?
How will you diagnose cystic fibrosis?
Do I need to take any preparatory steps before my sweat test, blood test, or fecal test?
What are my treatment options?
Which medications do you recommend I take to treat cystic fibrosis?
Do I have other conditions related to cystic fibrosis?
How will cystic fibrosis affect my lifestyle?
What signs should I look for that might indicate my condition is worsening?
What is my long-term prognosis?
Am I a good candidate for lung transplantation?
Do you recommend that I enroll in a clinical trial investigating a potential new treatment for cystic fibrosis?
