About Cystic fibrosis

Cystic fibrosis (CF) is a life-threatening disorder that causes severe lung damage and nutritional deficiencies.

An inherited condition, cystic fibrosis affects the cells that produce mucus, sweat, saliva and digestive juices. Normally, these secretions are thin and slippery, but in cystic fibrosis, a defective gene causes them to become thick and sticky. Instead of acting as a lubricant, the secretions plug up tubes, ducts and passageways, especially in the pancreas and lungs.

Respiratory failure is the most dangerous consequence of cystic fibrosis. Also, the secretions block pancreatic enzymes that help digest fats and proteins, and they prevent your body from absorbing key vitamins.

Causes

In cystic fibrosis, a defective gene alters a protein that regulates the normal movement of salt (sodium chloride) in and out of cells. This results in thick, sticky secretions in the respiratory and digestive tracts, as well as in the reproductive system. It also causes increased salt in sweat.

The affected gene, which is inherited from a child’s parents, is a recessive gene. With recessive genes, children need to inherit two copies of the gene, one from each parent, in order to have the disease. If children inherit only one copy, they won’t develop cystic fibrosis, but will be carriers and possibly pass the gene to their own children.

If two people who carry the defective gene conceive a child, there’s a 25 percent chance the child will have cystic fibrosis, a 50 percent chance the child will be a carrier of the cystic fibrosis gene, and a 25 percent chance the child will neither have the disease nor be a carrier.

People who carry the cystic fibrosis gene are healthy and have no symptoms — they may be carriers and not know it. Although parents often blame themselves when a child is born with cystic fibrosis, it’s important to remember that the causes of cystic fibrosis are not the result of anything a parent consciously does.

The role of fatty acids
Some experts believe that an imbalance of essential fatty acids may play a role in cystic fibrosis. People with cystic fibrosis appear to have excessively high levels of arachidonic acid and a deficiency of another fatty acid, docosahexaenoic acid.

Healthy people who carry one cystic fibrosis gene have fatty acid levels midway between those of people with cystic fibrosis and people with no genetic mutations for the disease. But the exact nature of the relationship between fatty acid levels and the gene defect that causes cystic fibrosis isn’t clear.

The greatest risk factor for cystic fibrosis is a family history of the disease. If both you and your partner come from families with cystic fibrosis, then each of your children has a one in four chance of having cystic fibrosis.

Your risk is also greater if you’re of Northern European ancestry. In that case, you have a one in 29 chance of carrying the gene. Among other ethnic groups in the United States, Hispanics have a one in 46 chance of carrying the gene, blacks have a one in 65 chance and Asian-Americans a one in 90 chance.

Symptoms

The specific signs and symptoms of cystic fibrosis can vary with the severity of the disease. For example, one child with cystic fibrosis may have respiratory problems but not digestive problems, while another child may have both. In addition, the signs and symptoms of cystic fibrosis may vary with age.

Signs and symptoms in newborns
In some newborns, the first sign may be a blockage of their intestines (meconium ileus). This occurs when meconium — tarry, greenish-black stools normally passed by an infant during the first day or two after birth — becomes so thick it can’t move through the intestines. Other signs in newborns may include:

  • Failure to grow
  • Bulky and greasy stools (steatorrhea)
  • Frequent respiratory infections

Signs and symptoms in children and young adults
Cystic fibrosis symptoms in children and young adults may include:

  • Salty taste to the skin. People with cystic fibrosis tend to have higher than normal amounts of salt (sodium chloride) in their sweat. This may be one of the first signs parents notice because they can taste the salt when they kiss their child.
  • Blockage in the bowels.
  • Foul-smelling, greasy stools.
  • Delayed growth.
  • Thick sputum. It’s easy for parents to overlook this sign because young children tend to swallow their sputum rather than cough it up.
  • Coughing or wheezing.
  • Frequent chest and sinus infections with recurring pneumonia or bronchitis.
  • Protrusion of part of the rectum through the anus (rectal prolapse). This is often caused by stools that are difficult to pass or by frequent coughing.
  • Enlargement or rounding (clubbing) of the fingertips and toes. Although clubbing eventually occurs in most people with cystic fibrosis, it also occurs in some people born with heart disease and other types of lung problems.

Cystic fibrosis may also be accompanied by:

  • Growths (polyps) in the nasal passages
  • Cirrhosis of the liver due to inflammation or obstruction of the bile ducts
  • Displacement of one part of the intestine into another part of the intestine (intussusception) in children older than age 4

Signs in newborns may include failure to grow, chronic respiratory problems — especially recurrent pneumonia — and frequent bulky, greasy stools.

Older children also may have diarrhea and frequent respiratory infections, including pneumonia. Failure to grow steadily on the growth percentile curve also may be a sign of cystic fibrosis, especially if other signs and symptoms are present.

Call your doctor right away if, after diagnosis, your child develops fever, a worsening cough, breathing difficulties, change in level of tiredness or decreased appetite.

In addition, if your child has received a diagnosis of cystic fibrosis, schedule regular examinations at a cystic fibrosis clinical center. Your child will also need to see your family doctor on a regular basis to have medications and any lung or digestive problems monitored.

Diagnosis

If you’re pregnant or trying to become pregnant, you may want to consider talking to your doctor about a cystic fibrosis carrier test for you and your partner. In the past, doctors usually tested only couples at increased risk — those with a personal or family history of cystic fibrosis — but many doctors now offer the test to all couples.

The test, which is performed in a lab on a sample of blood or saliva, can help determine whether you or your partner carries the gene for cystic fibrosis. If you’re already pregnant and the test shows that your baby may be at risk of cystic fibrosis, your doctor can conduct additional tests on your developing child. Because cystic fibrosis can’t be treated before birth, the purpose of these tests is to help you consider your plans for the future.

The decision to be screened for cystic fibrosis is personal and will depend on a number of factors, including your level of risk and your religious beliefs. In addition, some genetic mutations for cystic fibrosis can’t be detected by the current test. That means that in rare cases, your test may be normal and yet you may still be a carrier. The chances of this happening are small, however.

Sweat test
The standard diagnostic test for cystic fibrosis is a sweat test, which measures the amount of sodium or chloride in a person’s sweat. During the procedure, a small amount of an odorless sweat-producing chemical is applied to a small area on the arm or leg. An electrode attached to the area stimulates a very weak and painless electric current, causing a tingling or warm feeling. After several minutes, sweat is collected from the stimulated area and sent to a laboratory for analysis.

The sweat test is performed on two separate samples, which are usually taken on one occasion, to ensure that a false-positive or false-negative result hasn’t occurred. A consistently high level of salt indicates cystic fibrosis. This test doesn’t show whether someone has a mild or severe case of the disease, however, and it can’t predict how well someone with cystic fibrosis will do.

In addition, the sweat test may not always be useful in newborns. That’s because babies may not produce enough sweat for a reliable diagnosis in the first month of life. For this reason, doctors usually don’t perform a sweat test until an infant is at least several months old.

Other tests
If your newborn has signs and symptoms of cystic fibrosis, your doctor may perform a genetic analysis of a blood sample to confirm the diagnosis. Tests may also help determine the extent and severity of cystic fibrosis. Among these are tests to measure how well the lungs, pancreas and liver are working.

Because cystic fibrosis is an inherited disease, your doctor may suggest testing the brothers and sisters of a child with cystic fibrosis, even if they show no signs or symptoms. Other family members, especially first cousins, also may want to be tested. In most cases family members can be screened with a sweat test, although in some cases genetic blood testing may be appropriate.

Treatment

Many treatments exist for the symptoms and complications of cystic fibrosis. The main goal is to prevent infections, reduce the amount and thickness of secretions in the lungs, improve airflow, and maintain adequate calories and nutrition.

To accomplish these objectives, cystic fibrosis treatment may include:

  • Antibiotics. Newer antibiotics may more effectively fight the bacteria that cause lung infections in people with cystic fibrosis. Among these are aerosolized antibiotics that send medication directly into airways. One of the major drawbacks of long-term use of antibiotics is the development of bacteria that are resistant to drug therapy. In addition, using antibiotics over a long period of time can lead to fungal infections of the mouth, throat and respiratory tract.
  • Mucus-thinning drugs. When your white blood cells attack bacteria in your airways, DNA in your cells is released, making the mucus in your airways even thicker. The aerosolized drug dornase alfa (Pulmozyme) is an enzyme that fragments DNA, making mucus thinner and easier to cough up. Side effects of the drug may include airway irritation and sore throat.
  • Bronchodilators. Use of medications such as albuterol, which can be delivered by an inhaler or a nebulizer, may help keep open the bronchial tubes by clearing thick secretions.
  • Bronchial airway drainage. People with cystic fibrosis need a way to physically remove thick mucus from their lungs. This is often done by manually clapping with cupped hands on the front and back of the chest — a procedure that’s best performed with the person’s head over the edge of the bed so that gravity helps clear the secretions.

    In some cases an electric chest clapper, known as a mechanical percussor, is used. An inflatable vest that vibrates at high frequency also can help people with cystic fibrosis cough up secretions. Many adults and children with pulmonary cystic fibrosis need to have bronchial airway drainage at least twice a day for 20 to 30 minutes. Older children and adults can learn to do this themselves, especially if they use mechanical aids, such as vests and percussors. Young children need the aid of parents, grandparents or older siblings.

  • Oral enzymes and better nutrition. Cystic fibrosis can cause you to become malnourished because the pancreatic enzymes needed for digestion don’t reach your small intestine, preventing food from being absorbed. As a result, you may need many more calories than you otherwise would. Supplemental high-calorie nutrition, special fat-soluble vitamins and enteric-coated oral pancreatic enzymes can help you maintain or even gain weight.
  • Lung transplantation. Your doctor may suggest lung transplantation if you have severe breathing problems, life-threatening pulmonary complications or increasing resistance to antibiotics used to treat lung infections. Whether you’re a good candidate for the procedure depends on a number of factors, including your overall health, certain lifestyle factors and the availability of donor organs. Because both lungs are affected by cystic fibrosis, both need to be replaced. If your chest isn’t large enough to hold two adult donor lungs, your surgeon is likely to use two lower lobes contributed by two living donors. However it’s performed, lung transplantation is a major operation and may lead to serious complications, especially post-surgical infections.
  • Pain relievers. Ibuprofen (Advil, Motrin, others) may slow lung deterioration in some children with cystic fibrosis.

Future treatments
Major progress in cystic fibrosis research came in 1989, when researchers identified the genetic mutation that causes the disease. Since then scientists have been studying ways to insert copies of the normal gene into cells of the respiratory tract.

The challenge has been to find a reliable way to deliver the normal genetic material to affected cells that line the airways. Several methods have been developed as delivery systems, including using modified viruses, fat capsules (liposomes) and synthetic vectors. Clinical trials are under way to test the effectiveness of these delivery systems.

Other research is focusing on modifying the protein that the cystic fibrosis gene produces. This may help normalize the movement of salt and water in and out of the cells.

Complications

Frequent complications of cystic fibrosis are chronic respiratory infections, including pneumonia, bronchitis, chronic sinusitis and bronchiectasis — an abnormal dilation of the walls of the bronchial tubes that makes it more difficult to clear your airways. Asthma can result from chronic inflammation of the bronchial lining.

Respiratory infections are common because thick mucus blocks the airways and provides an ideal breeding ground for bacteria. The most common infective agent in people with cystic fibrosis is Pseudomonas aeruginosa — a bacterium that can cause increased inflammation of the respiratory tract. Although antibiotics can decrease the frequency and severity of attacks, the bacteria are never completely eradicated from the airways and the lungs. On the other hand, P. aeruginosa rarely causes pulmonary infections in healthy people and isn’t considered contagious.

People with cystic fibrosis may also develop bleeding from the lungs causing them to cough up blood (hemoptysis), respiratory failure or collapsed lung (pneumothorax) — a condition in which lung air leaks into the chest cavity through a small hole that forms in the lung’s outer layer. Lung disease eventually may cause the lower right chamber (right ventricle) of the heart to fail. Ultimately, complications from lung problems prove fatal for many people with cystic fibrosis.

Nutritional complications
In addition, cystic fibrosis makes you prone to chronic diarrhea and severe nutritional deficiencies. That’s because thick secretions obstruct the ducts in your pancreas, preventing enzymes that digest fats and proteins from reaching your intestines. These secretions also prevent your body from absorbing the fat-soluble vitamins A, D, E and K.

Cystic fibrosis affects the pancreas and because the pancreas controls the level of sugar in your blood, up to one in five people with cystic fibrosis may develop cystic fibrosis-related diabetes. In addition, the bile duct, the duct that carries bile from your liver and gallbladder to your small intestine, may become blocked and inflamed, leading to liver problems, such as cirrhosis.

Reproductive complications
Cystic fibrosis also affects the reproductive system. Because thick secretions often block the tube connecting the testes and prostate gland (vas deferens), many men with cystic fibrosis are infertile. But certain fertility methods and surgical procedures may sometimes make it possible for men with cystic fibrosis to become fathers.

Although women with cystic fibrosis may be less fertile than other women, it’s possible for them to conceive and to have successful pregnancies. Still, pregnancy can worsen the signs and symptoms of cystic fibrosis, so be sure to discuss the possible risks with your doctor. Using oral contraceptives also can sometimes aggravate certain symptoms of cystic fibrosis. Talk to your doctor about your birth control options.

Self-care

If you have a child with cystic fibrosis, one of the best things you can do is to learn as much as possible about the disease. Diet, medication and early recognition of infection are important.

Also important for most patients is performing daily chest percussion to drain mucus from your child’s lungs. Your doctor or respiratory therapist can show you the best way to perform this lifesaving procedure.

In addition, the following steps can help aid your child’s health:

  • Keep your child’s immunizations up to date. In addition to other usual childhood vaccines, this includes the pneumococcal and influenza vaccines. Cystic fibrosis doesn’t affect the immune system, but children with cystic fibrosis are more likely to develop complications when they become sick.
  • Encourage your child to lead as normal and active a life as possible. Exercise is extremely important for people of all ages who have cystic fibrosis. Regular exercise helps loosen mucus in your airways and strengthens your heart and lungs. And for many people with cystic fibrosis, participating in sports can improve confidence and self-esteem. It isn’t necessary to take part in an organized sport or take classes at a gym. Anything that gets you moving, including walking and biking, can help.
  • Make sure your child eats a healthy diet. Be sure to discuss your child’s dietary needs with your doctor or a nutritionist.
  • Use nutrition supplements. Provide the fat-soluble vitamin supplements and pancreatic enzymes your child needs to stay as healthy as possible.
  • Emphasize liquids. Encourage your child to drink plenty of liquids to help loosen the mucus. This is especially important in the summer when children are active and tend to lose a lot of fluids.
  • Eliminate smoke. Don’t smoke in your home or car, and don’t allow other people to smoke around your child. Secondhand smoke is harmful for everyone, but especially for people with cystic fibrosis.
  • Encourage hand washing. Teach everyone in your family to wash their hands thoroughly before eating, after using the bathroom, when coming home from work or school, and after being around a person who is sick. Hand washing is the best way to protect against infection.