Cystic Fibrosis Symptoms & Causes

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Contact the Cystic Fibrosis Center

We understand that you may have a lot of questions when your child is diagnosed with cystic fibrosis:

  • Is it painful?
  • Does my child need to be hospitalized?
  • How will it affect my child long-term?
  • What do we do next?

We’ve tried to provide some answers to those questions in the following pages, and when you meet with our experts, we can explain your child’s condition fully.







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What is cystic fibrosis?

Cystic fibrosis (CF) is a common hereditary (inherited) chronic disease that can affect multiple parts of your child’s body -– most commonly her lungs and digestive system. A defective gene causes the body to produce unusually thick, sticky mucus that:

  • clogs the lungs and leads to lung infections
  • obstructs the pancreas and stops natural enzymes from helping the body break down and absorb food

What does “cystic fibrosis” mean?

Fibrosis refers to an excessive amount of fibrous connective tissue in an organ. In cystic fibrosis, this build-up leads to cysts forming, most commonly in the lungs and pancreas.

How does CF affect my child’s respiratory system?

Normally, mucus is thin and can be easily cleared by the airways. With CF, mucus becomes thickened, sticky and gradually blocks the airways. Eventually, cysts may develop due to this blockage. This can result in:

  • Lung infections
    • These are quite common in children with CF, because bacteria that are normally cleared by the airways remain in the thickened mucus.

    • Many of these infections are chronic (recurring).

    • They are commonly caused either the pseudomonas aeruginosa (PA) or Staphylococcus (staph) bacteria.

  • Problems with the upper respiratory tract

    • About 10 to 20 percent of children with CF have nasal polyps­ — small protrusions of tissue from the lining of the nose — that need to be surgically removed.

    • Children with CF also have a high rate of sinus infections.

How does CF affect the digestive system?

1. The gene that has the CF mutation – the CFTR gene – controls the flow of water and certain salts in and out of the body's cells. The mutation means that mucus throughout your child’s body becomes thickened.

2. The pancreas secretes substances that help digestion. In around 90 percent of children with CF, these substances become thick, and cause ducts (passageways between organs) to become blocked, resulting in fewer enzymes.

3. With fewer digestive enzymes, your child will have difficulty absorbing the nutrients, her body needs, especially:

  • fats
  • some proteins
  • fat-soluble vitamins such as A, D, E and K

How can cystic fibrosis cause diabetes?

In addition to affecting the respiratory and digestive systems, cystic fibrosis can also lead to diabetes. This is because problems with the pancreas may become so severe that some of its cells are destroyed, leading to glucose intolerance and insulin-dependent diabetes.

About 35 percent of CF patients develop this type of diabetes in their 20s, and more than 40 percent develop the disease after age 30.

What other risks are associated with CF?

A small number of patients may also develop liver disease. Signs of liver disease include:

  • enlarged liver
  • swollen abdomen
  • yellowish skin
  • vomiting of blood

Nutrition and cystic fibrosis

How many calories does my child need?

Your child will need to ingest more calories than someone without CF for two reasons:

  • Her body may have difficulty absorbing nutrients.
  • It takes a lot of energy to fight infections and compensate for breathing problems.

The dietician on your child’s health care team will work with you to come up with a diet plan, but a good rule of thumb is to have her eat three meals and two to three snacks each day.

Does my child need extra vitamins?

Yes, your child may need to take extra vitamins. Vitamins A, D, E and K are known as fat-soluble vitamins, and since her body may have difficulty absorbing fats, it may be difficult for her to get enough of these vitamins from food.

There are vitamins specifically made for children with CF, and we can recommend the type and amount that are appropriate for her.

Does my child need extra salt?

Yes, many children with CF need extra salt in their diets because they lose more salt in their sweat than other children. You can add extra salt simply by adding salt to her meals and serving salty foods and snacks (chips, pretzels, fast foods, french fries, pickles, nuts and luncheon meats).

Remember that extra salt intake is especially important in the hot weather when your child is playing outside and sweating.

What if my child isn’t gaining weight?

Your child may not grow or gain weight despite having a high-calorie diet. If this happens, she may need supplemental feedings, as directed by her physician. This may involve her coming to the hospital.

Sometimes, patients with CF require long-term nutritional support through a feeding tube (gastrostomy or "G-tube") through the stomach wall.

Teens and CF

It can be hard enough to be a teenager without having to deal with a chronic illness like CF. The adolescent years can be especially intense to a teen with CF, and may lead to some poor decisions about how he takes care of himself. Understanding what your child is going through can help you support him during this important time - and help you cope, too.

Your child’s cognitive development

Research suggests that the brain isn’t fully developed until a person’s mid-20s. Because your child’s brain is still developing, there’s lots of “in the moment” thinking: Your teen may have a hard time thinking about the consequences of his actions.

This can lead to risk-taking behaviors, like substance abuse and sexual activity. And in the case of those with CF or other chronic illnesses, not taking medications and/or following through with chest therapy.

Your child’s emotional development

A big part of adolescence is navigating the territory between the security of childhood and the independence of adulthood. You may notice your child:

  • wanting more responsibility and to make his own decisions
  • testing boundaries and seeing how much he can get away with
  • exploring his own identity – figuring out who he is, what’s important to him and where he is headed in life

As part of this process, he may choose not to follow through with this treatment plan (known as “non-adherence”). This could happen for several reasons:

  • If he’s been feeling good and not getting sick, he may feel that he doesn’t need it.
  • He may feel a strong desire to feel “normal” and not have the requirements and restrictions that make him feel different from his peers.
  • He may resent the need for close monitoring of his health.
  • He may find it difficult to incorporate his treatment regimen into his daily routine.

Because of these things, he may feel angry and forget to do chest therapy and take medications.  

How you can help

Your support and understanding are more important than ever to your teen. Coping with a chronic illness is a stressful and emotional experience for teens and their families, and sometimes this can strain communication. Remember that good communication goes both ways:

  • Encourage your child to talk openly with you.
  • Keep your initial focus on listening to what your teen is saying, and making sure you understand what he means. Sometimes what a teen needs most is simply to feel understood. 

Here are some other ways you can support your teen:

  • Include your teen in decision making about his health care as early as appropriate.

  • Talk with your child about his medication. Make sure he knows what he’s taking and why. Stress the importance of taking the medication as prescribed. Help him figure out ways to be reminded that it’s time to take the medicine (such as setting an alarm on his cell phone).

  • Encourage your child to find online peer support among other CF patients. This can decrease his sense of being “different,” and reassure him that what he’s going through is normal.

  • Help your teen to set long-term academic and vocational goals.

  • Teens like to feel like active contributors to the family. Encourage your child to do chores and care for younger siblings. Sibling support is also important.

  • If appropriate, help your teen identify a trusted adult he can talk with about issues that he may not be comfortable talking to his family about.

  • Support your teen’s efforts to develop and sustain friendships and other social relationships.

What causes cystic fibrosis?

Cystic fibrosis is a genetic disease. Two things are true of all genetic diseases:

  • Their root cause is located on the cellular level.
  • They are inherited.

Because of this, we can look at what causes cystic fibrosis in two different ways—how it occurs on the cellular level and how a child comes to inherit the disease.

On the cellular level

As the name implies, a “genetic disease” is caused by something in the body’s genes. Genes are found on chromosomes—structures in the cells of our bodies that usually come in pairs.

One pair of chromosomes includes a gene called the CFTR (cystic fibrosis transmembrane conductance regulator) gene, and mutations or errors in this gene are what cause CF. This gene is large and complex, and more than 1000 different CF-related mutations have been identified.

Inheriting CF

If a baby is born with CF, it means she has inherited two CF genes: one from the mother and one from the father.

A person with only one CF gene is healthy and said to be a "carrier" of the disease. If both parents are carriers of the CF gene (they each have one copy of the defective gene, but do not have the disease themselves), their child has:

  • a 25 percent chance of inheriting both defective copies and having CF
  • a 50 percent chance of inheriting one defective copy and being a carrier
  • a 25 percent chance of not having CF and not carrying the gene

This type of inheritance is called "autosomal recessive."

What does autosomal recessive mean?

Autosomal means that the gene is on one of the pairs of chromosomes that do not determine gender, so that the disease equally affects males and females.

Recessive means that two copies of the gene, one inherited from each parent, are necessary to have the condition.

Symptoms of CF

The symptoms of CF differ for each child, and some children may not show signs of CF until later in life. Symptoms related to the respiratory system include:

  • chronic cough
  • coughing up blood
  • collapsed lung
  • clubbing (rounding and enlargement of the fingers and toes)
  • heart enlargement
  • nasal polyps (fleshy growths in the nose)
  • sinusitis (inflamed nasal sinuses)

Symptoms related to the digestive system include:

  • frequent, bulky, greasy stools
  • rectal prolapse (a condition in which part of the lower intestinal tract comes out of the anus)
  • fat in the stools
  • stomach pain
  • bloody diarrhea
  • poor growth
  • gallstones

Infants born with CF usually show symptoms within the first year. Your infant may be tested for CF if he has the following symptoms:

  • diarrhea that does not go away
  • foul-smelling stools
  • greasy stools
  • frequent episodes of wheezing
  • frequent episodes of pneumonia
  • persistent cough
  • skin tastes salty
  • poor growth
  • chronic sinus infection


Q: What is cystic fibrosis?

A: Cystic fibrosis (CF) is a common hereditary (inherited) chronic disease that affects two parts of your child’s body - her lungs and digestive system.

Q: What is the life expectancy for a child with CF?

A: The current life expectancy for someone with CF is about 37 years old—but those patients haven’t had lifelong treatment based on the most recent scientific advances. Today, a baby with CF is more than likely to live into her 40s and beyond.

Q: If my child has CF, what are the chances that I could have another child with CF?

A: Once parents have had a child with CF, there is a one in four, or 25 percent, chance with each subsequent pregnancy for another child to be born with CF. This means that there is a three out of four, or 75 percent chance, that another child will not have CF.

Q: If CF is genetic, how can my baby have it when my partner and I don’t?

A: Even though it’s an inherited disorder, finding out that your child has CF might be a surprise, since most of the time (in eight out of 10 families) there is no previous family history of CF. But many autosomal recessive conditions (which require that each parent contribute a gene with a mutation, even if neither actually has the condition) occur this way; since both parents are healthy, they may not known that they carry the gene.

Q: Can you be tested for mutations in the gene that causes CF?

A: Yes, testing for the CF gene can be done from a small blood sample. Laboratories generally test for the most common mutations, and most labs test for anywhere from 30 to 100 total mutations.

Unfortunately, not all of the genetic errors that cause the disease have been discovered. Because not all mutations are detectable, a person may still be a CF carrier even if testing shows no mutations.

Q: Can genetic testing prevent or stop my child’s CF?

A: Unfortunately, knowing the specific genetic mutation doesn’t tell us when your child will become sick, nor how sick he may get. Two children with the same genetic mutation may show different symptoms at different times.

That said, genetic testing is useful in that some therapies are effective for certain mutations and not others. This means that knowing the precise mutation can help us better target your child’s treatment.

Q: Should I undergo genetic testing for CF?

A: We recommend that you test for the CF gene if you have a family member with the disease, or if your partner is a known carrier of CF or affected with CF.

Q: How sick will my child get if he has CF?

A: Unfortunately, there’s no way of knowing how any individual case of CF will progress, but many CF patients lead full and happy lives. Following the treatment plan, performing therapies and taking medicines will help to ensure your child’s best possible outcome.

Q: Is there a cure?

A: At the present time, there is no cure for CF, but with medical and psychosocial support, many children and adolescents with CF can cope well and lead a productive life. The goals of treatment are to ease severity of your child’s symptoms and slow the progress of the disease.

Q: What are the treatment options?

There are a variety of treatments and therapies available for CF, and your child’s doctor will recommend the most appropriate ones for your child.

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