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cystic fibrosis





cystic fibrosis
A hereditary disease the symptoms of which usually appear shortly after birth. These symptoms include faulty digestion, breathing difficulties, and respiratory infections due to mucus accumulation, and excessive loss of salt in sweat. Cystic fibrosis (CF) affects mostly the lungs, pancreas, liver, intestines, sinuses, and sex organs.

Normally, mucus is watery. It keeps the linings of certain organs moist and prevents them from drying out or getting infected. But in CF, an abnormal gene causes mucus to become thick and sticky.





The mucus builds up in the lungs and blocks the airways. This makes it easy for bacteria to grow and leads to repeated serious lung infections. Over time, these infections can cause serious damage to the lungs.

The thick, sticky mucus can also block tubes, or ducts, in the pancreas. As a result, digestive enzymes that are produced by the pancreas cannot reach the small intestine. These enzymes help break down the food that is eaten. Without them, the intestines cannot absorb fats and proteins fully.

As a result:
  • Nutrients leave the body unused, and the individual can become malnourished.
  • The stools become bulky.
  • The individual may not get enough vitamins A, D, E, and K.
  • The individual may have intestinal gas, a swollen belly, and pain or discomfort.
The abnormal gene also causes the sweat to become extremely salty. As a result, during perspiration, the body loses large amounts of salt. This can upset the balance of minerals in the blood. The imbalance may cause the individual to have a heat emergency.

CF can also cause infertility (mostly in men).

The symptoms and severity of CF vary from person to person. Some people with CF have serious lung and digestive problems. Other people have more mild disease that doesn't show up until they are adolescents or young adults.

Respiratory failure is the most common cause of death in people with CF.

Until the 1980s, most deaths from CF occurred in children and teenagers. Today, with improved treatments, people with CF live, on average, to be more than 35 years old. Research continues to look for better treatments and, ultimately, a cure.


What causes cystic fibrosis?

Cystic fibrosis is caused by a defect in a gene called the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This gene makes a protein that controls the movement of salt and water in and out of the cells in the body. In people with CF, the gene does not work effectively. This causes the thick, sticky mucus and very salty sweat that are the main features of CF. Each of us inherits two CFTR genes, one from each parent.
  • Children who inherit an abnormal CFTR gene from each parent will have CF.
  • Children who inherit an abnormal CFTR gene from one parent and a normal CFTR gene from the other parent will not have CF. They will be CF carriers.
CF carriers:
  • Usually have no symptoms of CF
  • Live normal lives
  • Can pass the abnormal CFTR gene on to their children
When two CF carriers have a baby, the baby has a:
  • One in four chance of inheriting two abnormal CFTR genes and having CF.
  • One in four chance of inheriting two normal CFTR genes and not having CF or being a carrier.
  • Two in four chance of inheriting one normal CFTR gene and one abnormal CFTR gene. The baby will not have CF but will be a CF carrier like its parents.

cystic fibrosis inheritance


Who is at risk for cystic fibrosis?

About 30,000 people in the United States have cystic fibrosis.
  • It affects both males and females.
  • It affects people from all racial and ethnic groups but is most common among Caucasians whose ancestors came from northern Europe.
CF is one of the most common inherited diseases among Caucasians.

About 1 in every 3,000 babies born in the United States has CF.

CF is also common in:
  • Latinos
  • Native Americans, especially the Pueblo and Zuni
CF is much less common among:
  • African Americans
  • Asian Americans

About 12 million Americans are carriers of an abnormal CF gene. Many of them do not know that they are CF carriers.


What are the signs and symptoms of cystic fibrosis?

Most of the symptoms of cystic fibrosis are caused by the thick, sticky mucus. The most common symptoms include:
  • Frequent coughing that brings up thick sputum, or phlegm.
  • Frequent bouts of bronchitis and pneumonia. They can lead to inflammation and permanent lung damage.
  • Salty-tasting skin.
  • Dehydration.
  • Infertility (mostly in men).
  • Ongoing diarrhea or bulky, foul-smelling, and greasy stools.
  • Huge appetite but poor weight gain and growth. This is called "failure to thrive." It is a result of chronic malnutrition because the individual does not get enough nutrients from his or her food.
  • Stomach pain and discomfort caused by too much gas in the intestines.
CF can also lead to other medical problems, including:
  • Sinusitis. The sinuses are air-filled spaces behind the eyes, nose, and forehead. They produce mucus and help keep the lining of the nose moist. When the sinuses become swollen, they get blocked with mucus and can become infected. Most people with CF develop sinusitis.
  • Bronchiectasis. Bronchiectasis is a lung disease in which the bronchial tubes, or large airways in the lungs, become stretched out and flabby over time and form pockets where mucus collects. The mucus provides a breeding ground for bacteria. This leads to repeated lung infections. Each infection does more damage to the bronchial tubes. If not treated, bronchiectasis can lead to serious illness, including respiratory failure.
  • Pancreatitis. Pancreatitis is inflammation in the pancreas that causes pain.
  • Episodes of intestinal blockage, especially in newborns.
  • Nasal polyps, or growths in the nose, that may require surgery.
  • Clubbing. Clubbing is the widening and rounding of the tips of the fingers and toes. It develops because the lungs are not moving enough oxygen into the blood stream.
  • Collapsed lung. This is also called pneumothorax.
  • Rectal prolapse. Frequent coughing or problems passing stools may cause rectal tissue from inside the body to move out of the rectum.
  • Liver disease due to inflammation or blocked bile ducts.
  • Diabetes.
  • Gallstones.
  • Low bone density because the individual does not get enough vitamin D.

How is cystic fibrosis diagnosed?

First, a doctor will obtain a detailed medical and family history and perform a thorough physical examination. The doctor may order some tests to ensure an accurate diagnosis.

The sweat test is the most useful test for diagnosing cystic fibrosis. It measures the amount of salt in the sweat. For this test, a small amount of a chemical called pilocarpine is rubbed on the patient's arm or leg. An electrode is then attached to this spot. The electrode provides a mild electric current that produces sweat. This may cause tingling or a feeling of warmth. The area is then covered with a gauze pad or filter paper and wrap in plastic. After 30 to 40 minutes, the plastic is removed so the sweat that collected on the pad or paper can be analyzed. The test is usually done twice. High salt levels mean CF.

The following tests may also be carried out to understand more about a patient's condition and how to treat it:
  • Blood tests to look for an abnormal CF gene or other things that indicate CF.
  • Chest X-ray. A chest X-ray takes a picture of the lungs. It can show scarring from inflammation in the lungs.
  • Sinus X-ray. This test may show signs of sinusitis.
  • lung function tests can measure:
    • How much air the lungs can hold
    • How quickly the individual can breathe air out of his or her lungs
    • How well the lungs add oxygen to and remove carbon dioxide from the blood
  • Sputum (phlegm) cultures. A sample of sputum is taken to see what bacteria are growing in it.
If the patient is pregnant, prenatal genetic tests can find out if the baby has CF:
  • In amniocentesis, a hollow needle is inserted through the abdominal wall into the uterus to obtain cells from the amniotic fluid around the baby. The fluid is then tested to see if both of the baby's CFTR genes are normal.

  • In chorionic villus sampling, ultrasound is used to guide a thin tube through the vagina and cervix into the uterus and remove a tiny piece of the placenta to biopsy. The cells of the placenta are then tested to see if the baby has CF.
Some States are now testing the blood of all newborns for CF.

CF carrier testing

Individuals may want to check whether they are a CF carrier, if:
  • They have a family history of CF.
  • They are a partner of someone with CF.
  • They are a couple planning a pregnancy.
A genetics counselor at your local hospital can take a blood or saliva sample to see if it contains the abnormal CFTR gene that causes CF. It will detect 9 out of 10 cases of CF. Some insurance plans cover genetic testing.


How is cystic fibrosis treated?

There still is no cure for cystic fibrosis, but treatments have improved greatly in recent years. The goals of CF treatment are to:
  • Prevent and control infections in the lungs.
  • Loosen and remove the thick, sticky mucus from the lungs.
  • Prevent blockages in the intestines.
  • Provide adequate nutrition.

Treatment for lung problems

The main treatments for lung problems in people with CF are:
  • Antibiotics for infections of the airways
  • Chest physical therapy
  • Exercise
  • Other medications

Antibiotics

Most people with CF have ongoing, low-grade lung infections. Sometimes, these infections become so serious that the indicidual may need to be hospitalized. Antibiotics are the primary treatment.

Several different types of antibiotics may be given. The choice of antibiotics depends on:
  • The strains of bacteria involved
  • How serious the condition is
  • Previous history of antibiotic use
The different types of antibiotics include:
  • Oral antibiotics for relatively mild airway infections.
  • Inhaled antibiotics, such as tobramycin. They may be used alone or with oral antibiotics.
  • Intravenous antibiotics for severe infections or when none of the oral antibiotics work.
  • Antibiotics, such as azithromycin, that also reduce inflammation.

Chest physical therapy

Chest physical therapy (CPT) is also called chest clapping or percussion. It involves pounding the chest and back over and over again to dislodge the mucus from the lungs so that it can be coughed up. CPT for cystic fibrosis should be done three to four times each day.

CPT is also often referred to as postural drainage. This involves the individual sitting or lying on their stomach with their head down while CPT is performed. This allows gravity to help drain the mucus from the lungs.

Because CPT is hard or uncomfortable for some people, several devices have been developed recently that may help with CPT. The devices include:
  • An electric chest clapper, known as a mechanical percussor.
  • An inflatable therapy vest that uses high-frequency air waves to force the mucus out of the lungs.
  • A "flutter" device, a small hand-held device that the individual breathes out through. It causes vibrations that dislodge the mucus.
  • A positive expiratory pressure (PEP) mask that creates vibrations that help break the mucus loose from the airway walls.
Several breathing techniques may also help dislodge the mucus. These techniques include:
  • Forced expiration technique (FET) – forcing out a couple of breaths or huffs and then doing relaxed breathing
  • Active cycle breathing (ACB) – FET with deep breathing exercises that can loosen the mucus in the lungs and help open the airways

Exercise

Aerobic exercise helps:
  • Loosen the mucus
  • Encourage coughing to clear the mucus
  • Improve overall physical condition
If an individual exercises regularly, he or she may be able to cut back on the chest therapy. A doctor should be consulted before doing this.


Other medications

Anti-inflammatory medications may help reduce the inflammation in the lungs that is caused by ongoing infections. These medications include:
  • Inhaled or, sometimes, oral steroids. Steroids are the most effective anti-inflammatory medicines.
  • Ibuprofen, a type of non-steroidal anti-inflammatory medicine. It may slow the progress of CF in young children with mild symptoms.
  • Bronchodilators, which are inhaled drugs that relax the muscles around the airways so that the airways can open up. They should be taken just before CPT to help clear mucus.
Mucus-thinning drugs reduce the stickiness of mucus in the airways. They include:
  • Human DNase (Dornase Alfa), a drug that loosens the mucus in the lungs. It may lead to shorter hospital stays.
  • Acetylcysteine and saline.
  • Saline washes of the nasal passages, which may help clear sinuses.

Oxygen therapy

If the level of oxygen in the blood is too low, oxygen therapy may be needed. Oxygen is usually given through nasal prongs or a mask.


Lung transplantation

Surgery to replace one or both of the lungs with healthy lungs from a human donor may help the individual. Some of the factors that determine whether a person can undergo lung transplantation include:
  • The type of bacteria in the lungs
  • The patient's age and weight
  • The medications being taken
  • Whether the patient has other medical conditions, including osteoporosis
  • How well the lungs are functioning

Management of digestive problems

Nutritional therapy can improve growth and development, strength, and exercise tolerance. It may also make an individual strong enough to resist some lung infections. Nutritional therapy includes a well-balanced, high-calorie diet that is low in fat and high in protein.

As part of your nutritional therapy, a doctor may:
  • Prescribe oral pancreatic enzymes to help the patient digest fats and proteins and absorb more vitamins. The enzymes should be taken in capsule form before every meal, including snacks.

  • Recommend supplements of vitamins A, D, E, and K to replace the fat-soluble vitamins that the patient's intestines cannot absorb.

  • Recommend use of a feeding tube, called a gastrostomy tube or T-tube, to add more calories at night while the person are sleeping. The tube is placed in the stomach. Before bed each night, a bottle with a nutritional solution is attached to the entrance of the tube. It feeds the individual while they sleep.
Other treatments for the digestive problems caused by CF may include:
  • Enemas and mucus-thinning medications to treat intestinal blockages
  • Medicines that reduce stomach acid and help the oral pancreatic enzymes work better

Living with cystic fibrosis

People with cystic fibrosis should learn as much as they can about the disease and work closely with their doctors to learn how to manage it.

Ongoing medical care is important. Individuals with CF should seek treatment from a team of doctors, nurses, and respiratory therapists who specialize in CF. These specialists are often located at CF Foundation Centers in major medical centers.

Good self-care includes:
  • Eating a healthy diet
  • Avoiding tobacco smoke
  • Washing hands often to reduce the chances of infection
  • Exercising frequently
  • Drinking lots of fluids
  • Doing chest physical therapy every day
  • Having annual flu and other appropriate vaccinations
  • Taking medicines as prescribed
People with CF can expect to have a normal sex life.
  • Most men with CF are infertile, but they may be helped with modern reproductive techniques.
  • Although most women with CF may be less fertile than women who don't have CF, they usually can have children.
Having a positive attitude is also helpful.

Parents of someone with CF should not feel guilty about passing it on to their children. And they should not be overprotective; children with CF should be encouraged to be active and self-reliant.


Related categories

   • HEALTH AND DISEASE
   • GENETICS AND HEREDITY

Source: U.S. National Heart, Lung and Blood Institute