What Is Cystic Fibrosis? Symptoms, Causes, Diagnosis, Treatment, and Prevention

囊性纤维化(CF)是一种慢性遗传障碍that causes thickened mucus to form in your lungs,pancreas, and other organs in the body.

When mucus clogs airways in your lungs, infections and lung damage can occur.

Mucus in the pancreas can prevent the release of digestive enzymes, which your body needs to break down food and absorb nutrients.

Cystic fibrosis is considered a life-threatening condition, but its symptoms and severity can vary greatly depending on your age, the type of genetic mutation you have, and your overall health. (1)

Cystic fibrosis symptoms vary with the disease’s severity. Symptoms can also change in the same patient over time. Some people may not experience any CF symptoms until they become teenagers or adults.

CF symptoms usually affect the respiratory and digestive systems, though less-common symptoms such aspancreatitis(inflammation of the pancreas) are also possible. Typical CF signs and symptoms may include:

• Salty-tasting skin
• Persistentcough
• Coughing upphlegmor bloody mucus
• Wheezingorshortness of breath
• Frequent lung or sinus infections
• Inability to tolerate exercise
• Stuffy nose or inflamed nasal passages
• Sinus pain or pressure
• Poor growth
• Weight loss or loss of appetite
• Greasy, foul-smelling, or bulky stools
• Difficult bowel movements or severeconstipation
• Clubbed fingers (wide and rounded tips of the fingers)
• Fatigue (2)

Learn More About Signs and Symptoms of Cystic Fibrosis

Cystic fibrosis is a genetic disease. It's caused by a defective gene that a person inherits from their parents.

The faulty gene contains an abnormality, called a mutation, which changes a protein (known as CFTR) that's responsible for regulating the movement of salt in and out of the body’s cells.

There are 1,800 mutations known to cause cystic fibrosis.

People with the disease inherit two copies of the cystic fibrosis gene — one from each parent.

Both your parents must have at least one copy of this defective gene for you to have cystic fibrosis. If both your parents have the cystic fibrosis gene, you have about a 25 percent chance of developing the disease.

If you inherit one copy of the gene, you won't develop cystic fibrosis, but you'll be a carrier and may pass it on to your children.

There's also a chance that you won't inherit the cystic fibrosis gene or the disorder even if your parents are carriers.

According to theCystic Fibrosis Foundation (CFF), each time two CF carriers have a child, the chances are:

• 25 percent that the child will have CF
• 50 percent that the child will be a carrier but will not have CF
• 25 percent that the child will not be a carrier and will not have CF (3)

Cystic fibrosis can be diagnosed via a newborn screening test. All 50 U.S. states now routinely screen newborns for the disease.

If the newborn screening comes back positive for CF, more tests are done to confirm a diagnosis. These may include the following:

• Sweat testmeasures levels of chloride in a person’s sweat.
• Genetic testchecks for a cystic fibrosis gene defect.

Today, most children arediagnosed with cystic fibrosisby age 2 years. (4) Still, some people with CF are diagnosed as adults and will need to undergo diagnostic procedures, such as a sweat test or genetic test, to see if they have CF.

Getting an early diagnosis is important because the outcomes are better when treatments are started sooner.

Genetic testing can also be done before or during pregnancy to determine if a parent or the fetus has cystic fibrosis or is a carrier. (2)

Prognosis of Cystic Fibrosis

There’s no cure for cystic fibrosis, but the outlook has greatly improved in recent years.

In the 1970s, most patients with CF didn’t live beyond their teen years.

今天,由于改进治疗方案,expected age of survival is more than 36 years old, with CF foundation patient registry data finding a median predicted survival of CF patients above 45 years old. (5)

Cystic fibrosis is a lifetime disease. You can’t cure or get rid of it. But, as treatments and management strategies improve there is increasing likelihood of living into adulthood with a high quality of life. (5)

While there’s no cure for CF, certain treatments can help ease symptoms and prevent further problems.

Goals ofcystic fibrosis treatmenttypically include:

• Treating and preventing lung infections
• Loosening and removing mucus from the lungs
• Maintaining lung function
• Treating and preventing blockages in the intestines
• Providing nutrition and preventingdehydration(2)

Medication Options

Different medicines are used to treat cystic fibrosis and control symptoms. Some include:

• Antibiotics
• Anti-inflammatories
• Bronchodilators
• Mucus thinners

The U.S. Food and Drug Administration (FDA) has also approved the following oral medications for people with cystic fibrosis who have one or more mutations in the CFTR gene. They are in the category of CFTR modulator therapies:

• TrikaftaThis is a newer combination medicine that contains the drugselexacaftor, ivacaftor, and tezacaftor.
• SymdekoIt contains tezacaftor andivacaftor.
• OrkambiThis drug containslumacaftorand ivacaftor.
• Ivacaftoris also sold under the brand nameKalydeco. (2)

Pulmonary Rehabilitation

Pulmonary rehabilitation is a technique that can improve lung function. It’s usually performed as an outpatient therapy and involves physical exercises and breathing techniques. As part of the program, you may also receive counseling, support, and nutrition advice. (2)

Airway Clearing

Airway clearance methods, also known as chest physical therapy, may help relieve mucus obstruction for people with cystic fibrosis.

The techniques aim to loosen the thickened mucus in the lungs, so it’s easier to cough up. (2)

Surgeries and Other Therapies or Procedures

Sometimes people with cystic fibrosis require procedures to relieve symptoms or treat complications. These may include:

• Oxygen therapy
• Nasal orsinus surgery
• A feeding tube
• Bowel surgery
• Noninvasive ventilation (involves using a nose or mouth mask to provide positive pressure in the airway and lungs)
• Lung or liver transplant (2)

Alternative and Complementary Therapies

Some people with cystic fibrosis turn to alternative treatments to ease their symptoms. You should always talk to your doctor before trying an alternative approach.

There are many nutritional and herbal supplements available for CF. Common options include omega-3 fatty acids, coenzyme Q10,probiotics, digestive enzymes, green tea, bromelain, milk thistle, and more.

Additionally, some people report improvement with acupuncture or massage. As with any medication or drug, it is best to speak to your physician before starting any complementary and alternative medicine (CAM) therapy so he or she may address potential interactions, risks, or side effects, even if the risk could be low. (6)

Cystic Fibrosis and Diet

It can be tough for people with cystic fibrosis to maintain a normal weight because the disease causes damage to the digestive system and leads to malnourishment.

Patients require more calories because the lack of digestive enzymes produced by the pancreas results in a failure to properly digest what they eat.

As a result, people with the disease must balance consuming foods that are high in calories, fat, and protein, while still eating nutritiously. (2)

Learn More About Treatment for Cystic Fibrosis: Medication, Alternative and Complementary Therapies, Surgery Options, and More

Prevention of Cystic Fibrosis

There’s no way to prevent cystic fibrosis, but there are some measures you can take to minimize your risk of complications. These include:

• 多喝水帮助薄mucus.
• Eat a healthy, well-balanced diet.
• Stay up-to-date on vaccinations.
• Exercise regularly.
• Don’t smoke.
• Practice good hand-washing techniques to prevent infection.
• Keep all appointments with your healthcare team. (2)

Chronic respiratory infection is the most common complication of cystic fibrosis, but the condition can lead to a range of health issues affecting other parts of the body.

The following are some typical CF complications.

Chronic Infections

Pneumoniaandbronchitisare common infections in people with cystic fibrosis. Individuals with the disease are at greater risk of getting lung infections because mucus that builds up in the lungs allows germs to thrive. Minimizing exposure to germs is critical for CF patients.

Infections can be caused by routine, community-acquired bacteria such as链球菌orHaemophilus; more serious bacteria likeStaphylococcus aureus; or gram-negative bacteria such asPseudomonasorKlebsiella.

Fungal organisms or atypical mycobacteria can also cause infections in people with cystic fibrosis.

“There are strict guidelines about steps people with CF should follow to minimize the risk of catching some of the more worrisome infections,” saysNoah Lechtzin, MD, the director of the adult cystic fibrosis program and an associate professor of medicine at Johns Hopkins Medicine in Baltimore.

As a rule, the CFF advises that people with CF maintain a minimum distance of six feet from other CF patients and people who are ill. (7) Droplets containing germs that are released into the air when someone sneezes or coughs can travel several feet and land in another person’s mouth, nose, or eyes.

Bronchiectasis

This chronic condition damages the airways in the lungs (bronchi). The walls of the bronchi thicken from inflammation and infection, making it harder for people with cystic fibrosis to breathe.

Some signs of bronchiectasis resembleacute bronchitis. Common symptoms include shortness of breath, wheezing, fatigue, and coughing up green or yellow mucus. (8)

Nasal Polyps

Nasal polyps are benign tumors made up of inflamed tissues. These small sacs can develop in the nose, leading to chronic congestion and difficulty breathing through the nose.

They are more common in people with cystic fibrosis and other conditions such as allergic rhinitis,asthma, andchronic sinusitis. (2)

Respiratory Failure

Lung disease accounts for more than 90 percent of deaths in people with cystic fibrosis, according to CFF data. (9)

Lung tissue is sometimes damaged so badly that the lungs stop working. In this case patients may undergo evaluation and planning for a lung transplant.

Pneumothorax

This condition, also known as a collapsed lung, happens when air leaks from the lungs and collects in the space that separates the lungs from the chest wall. It causes chest pain and shortness of breath. It is more common in older CF patients.

Diabetes

Almost 20 percent of people with cystic fibrosis will develop diabetes by age 30, according to the Mayo Clinic. (2)

Cystic fibrosis–related diabetes (CFRD) shares some signs in common with both type 1 and type 2 diabetes. Thethick mucusassociated with CF causes scarring of the pancreas, the organ that produces insulin. As a result, CF patients can become insulin deficient (likepeople with type 1 diabetes). Like people with type 2 diabetes, CF patients can become insulin resistant.

People with CFRD may not show any signs or symptoms and may not know they have it unless they are tested specifically for diabetes.

Nutritional Deficiencies or Malnutrition

When the disease causes mucus to block the tubes that carry digestive enzymes from the pancreas to the intestines, your body can't absorb important vitamins and nutrients. This is often referred to asexocrine pancreatic insufficiency (EPI). Approximately 85 percent of CF patients are exocrine pancreatic insufficient. (10)

Studies have shown that prevention of malnutrition is associated with a better course of pulmonary disease and longer patient survival.

Intestinal Obstruction

This type of blockage keeps food or liquid from passing through the bowel.

Distal intestinal obstruction syndrome (DIOS) is a common CF complication, with an estimated 5 to 12 cases per 1,000 patients annually among children, and higher rates reported in adults. DIOS is mainly seen in patients withpancreatic insufficiency. (11)

Blocked Bile Duct

Your bile duct can become blocked and inflamed, which may lead to liver problems orgallstones.

Research suggests that cystic fibrosis–associatedliver disease(CFLD) affects approximately 30 percent of CF patients. CFLD is believed to be the third most frequent cause of death in people with CF, after lung disease and complications related to organ transplants. (12)

Acid Reflux

This happens when stomach acid flows back into the esophagus; it can trigger coughing.

Gastroesophageal reflux (GER) is common in CF patients, with studies estimating its prevalence as ranging from 35 percent to 81 percent. Research suggests that CF patients who have GER have more severe lung disease with lower pulmonary function and increased respiratory exacerbations. (13)

Infertility

Nearly all men with cystic fibrosis are infertile because the tube that connects the testes and theprostate glandbecomes blocked with mucus or is missing altogether. (14)

While most women with CF are able to carry a child, impaired lung function and nutrition can raise their risk of health complications during pregnancy.

Osteoporosis and Osteopenia

People with cystic fibrosis are more prone to developingosteoporosisandosteopenia, two common bone diseases. Lung disease and malnutrition associated with CF can compromise bone health.

Low bone mineral density (BMD) is common in adult CF patients.

Certain medications taken by CF patients, such as steroids to help respiratory function, also can adversely affect bone strength.

Arthritis

CF patients have a high risk of joint inflammation and pain, particularly as they age.

Arthritis, the most common type of joint pain in people with CF, can come and go over time.

Dehydration or Electrolyte Imbalance

People with cystic fibrosis have saltier sweat, which may affect the balance of minerals in the blood and be related to dehydration.

About 30,000 people are living with cystic fibrosis in the United States as of 2019, according to theCystic Fibrosis Foundation Patient Registry. There are approximately 70,000 people with CF worldwide. About 1,000 new cases are diagnosed each year in the United States.

More than 75 percent of people with the disease are diagnosed by age 2; and more than half of all people living with cystic fibrosis are 18 or older.

CF occurs predominantly in white populations, at a rate of 1 in 2,500 births. Between 2 percent and 5 percent of white people are carriers of the CFTR gene mutation but have no overt clinical signs of disease. The disease is less common among African Americans, occurring at the much lower frequency of approximately 1 out of 17,000 births. (15)

CF gene mutations are most prevalent in persons of northern and central European ancestries or of Ashkenazi Jewish descent. They are rarely found in Native Americans, Asians, or native Africans. (16)

CF is equally common among men and women, but women patients fare significantly worse than male patients with the disease. The median survival age for female CF patients is about three years younger than it is for men, but the reasons for the poorer survival rates among women are not completely understood. (17)

While CF is more common in white people than in other races, research published in the journalChestin 2015 found that Hispanics with the disease may face poorer outcomes. Indeed, Hispanic Americans were nearly three times more likely to die of cystic fibrosis than non-Hispanic patients.

Researchers are continuing to study why this potential disparity exists. (18,19)

Managing other health problems is important if you have cystic fibrosis.

Some conditions that are closely linked to cystic fibrosis include:

• Diabetes
• Liver disease
• Osteoporosis
• Pneumonia
• Arthritis (2,20)

American Lung Association

CysticFibrosis.com

Cystic Fibrosis Foundation

Cystic Fibrosis Worldwide